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Title 40

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Title 40

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Editorial codification of the general and permanent rules published in the Federal Register.

PART 141 - NATIONAL PRIMARY DRINKING WATER REGULATIONS
Authority:

42 U.S.C. 300f, 300g-1, 300g-2, 300g-3, 300g-4, 300g-5, 300g-6, 300j-4, 300j-9, and 300j-11.

Source:

40 FR 59570, Dec. 24, 1975, unless otherwise noted.

Note:

For community water systems serving 75,000 or more persons, monitoring must begin 1 year following promulation and the effective date of the MCL is 2 years following promulgation. For community water systems serving 10,000 to 75,000 persons, monitoring must begin within 3 years from the date of promulgation and the effective date of the MCL is 4 years from the date of promulgation. Effective immediately, systems that plan to make significant modifications to their treatment processes for the purpose of complying with the TTHM MCL are required to seek and obtain State approval of their treatment modification plans. This note affects §§ 141.2, 141.6, 141.12, 141.24 and 141.30. For additional information see 44 FR 68641, Nov. 29, 1979.

Subpart A - General
§ 141.1 Applicability.

This part establishes primary drinking water regulations pursuant to section 1412 of the Public Health Service Act, as amended by the Safe Drinking Water Act (Pub. L. 93-523); and related regulations applicable to public water systems.

§ 141.2 Definitions.

As used in this part, the term:

Act means the Public Health Service Act, as amended by the Safe Drinking Water Act, Public Law 93-523.

Action level, is the concentration of lead or copper in water specified in § 141.80(c) which determines, in some cases, the treatment requirements contained in subpart I of this part that a water system is required to complete.

Bag filters are pressure-driven separation devices that remove particulate matter larger than 1 micrometer using an engineered porous filtration media. They are typically constructed of a non-rigid, fabric filtration media housed in a pressure vessel in which the direction of flow is from the inside of the bag to outside.

Bank filtration is a water treatment process that uses a well to recover surface water that has naturally infiltrated into ground water through a river bed or bank(s). Infiltration is typically enhanced by the hydraulic gradient imposed by a nearby pumping water supply or other well(s).

Best available technology or BAT means the best technology, treatment techniques, or other means which the Administrator finds, after examination for efficacy under field conditions and not solely under laboratory conditions, are available (taking cost into consideration). For the purposes of setting MCLs for synthetic organic chemicals, any BAT must be at least as effective as granular activated carbon.

Cartridge filters are pressure-driven separation devices that remove particulate matter larger than 1 micrometer using an engineered porous filtration media. They are typically constructed as rigid or semi-rigid, self-supporting filter elements housed in pressure vessels in which flow is from the outside of the cartridge to the inside.

Clean compliance history is, for the purposes of subpart Y, a record of no MCL violations under § 141.63; no monitoring violations under § 141.21 or subpart Y; and no coliform treatment technique trigger exceedances or treatment technique violations under subpart Y.

Coagulation means a process using coagulant chemicals and mixing by which colloidal and suspended materials are destabilized and agglomerated into flocs.

Combined distribution system is the interconnected distribution system consisting of the distribution systems of wholesale systems and of the consecutive systems that receive finished water.

Community water system means a public water system which serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents.

Compliance cycle means the nine-year calendar year cycle during which public water systems must monitor. Each compliance cycle consists of three three-year compliance periods. The first calendar year cycle begins January 1, 1993 and ends December 31, 2001; the second begins January 1, 2002 and ends December 31, 2010; the third begins January 1, 2011 and ends December 31, 2019.

Compliance period means a three-year calendar year period within a compliance cycle. Each compliance cycle has three three-year compliance periods. Within the first compliance cycle, the first compliance period runs from January 1, 1993 to December 31, 1995; the second from January 1, 1996 to December 31, 1998; the third from January 1, 1999 to December 31, 2001.

Comprehensive performance evaluation (CPE) is a thorough review and analysis of a treatment plant's performance-based capabilities and associated administrative, operation and maintenance practices. It is conducted to identify factors that may be adversely impacting a plant's capability to achieve compliance and emphasizes approaches that can be implemented without significant capital improvements. For purpose of compliance with subparts P and T of this part, the comprehensive performance evaluation must consist of at least the following components: Assessment of plant performance; evaluation of major unit processes; identification and prioritization of performance limiting factors; assessment of the applicability of comprehensive technical assistance; and preparation of a CPE report.

Confluent growth means a continuous bacterial growth covering the entire filtration area of a membrane filter, or a portion thereof, in which bacterial colonies are not discrete.

Consecutive system is a public water system that receives some or all of its finished water from one or more wholesale systems. Delivery may be through a direct connection or through the distribution system of one or more consecutive systems.

Contaminant means any physical, chemical, biological, or radiological substance or matter in water.

Conventional filtration treatment means a series of processes including coagulation, flocculation, sedimentation, and filtration resulting in substantial particulate removal.

Corrosion inhibitor means a substance capable of reducing the corrosivity of water toward metal plumbing materials, especially lead and copper, by forming a protective film on the interior surface of those materials.

CT or CTcalc is the product of “residual disinfectant concentration” (C) in mg/1 determined before or at the first customer, and the corresponding “disinfectant contact time” (T) in minutes, i.e., “C” × “T”. If a public water system applies disinfectants at more than one point prior to the first customer, it must determine the CT of each disinfectant sequence before or at the first customer to determine the total percent inactivation or “total inactivation ratio.” In determining the total inactivation ratio, the public water system must determine the residual disinfectant concentration of each disinfection sequence and corresponding contact time before any subsequent disinfection application point(s). “CT99.9” is the CT value required for 99.9 percent (3-log) inactivation of Giardia lamblia cysts. CT99.9 for a variety of disinfectants and conditions appear in tables 1.1-1.6, 2.1, and 3.1 of § 141.74(b)(3).

is the inactivation ratio. The sum of the inactivation ratios, or total inactivation ratio shown as

is calculated by adding together the inactivation ratio for each disinfection sequence. A total inactivation ratio equal to or greater than 1.0 is assumed to provide a 3-log inactivation of Giardia lamblia cysts.

Diatomaceous earth filtration means a process resulting in substantial particulate removal in which (1) a precoat cake of diatomaceous earth filter media is deposited on a support membrance (septum), and (2) while the water is filtered by passing through the cake on the septum, additional filter media known as body feed is continuously added to the feed water to maintain the permeability of the filter cake.

Direct filtration means a series of processes including coagulation and filtration but excluding sedimentation resulting in substantial particulate removal.

Disinfectant means any oxidant, including but not limited to chlorine, chlorine dioxide, chloramines, and ozone added to water in any part of the treatment or distribution process, that is intended to kill or inactivate pathogenic microorganisms.

Disinfectant contact time (“T” in CT calculations) means the time in minutes that it takes for water to move from the point of disinfectant application or the previous point of disinfectant residual measurement to a point before or at the point where residual disinfectant concentration (“C”) is measured. Where only one “C” is measured, “T” is the time in minutes that it takes for water to move from the point of disinfectant application to a point before or at where residual disinfectant concentration (“C”) is measured. Where more than one “C” is measured, “T” is

(a) for the first measurement of “C”, the time in minutes that it takes for water to move from the first or only point of disinfectant application to a point before or at the point where the first “C” is measured and

(b) for subsequent measurements of “C”, the time in minutes that it takes for water to move from the previous “C” measurement point to the “C” measurement point for which the particular “T” is being calculated. Disinfectant contact time in pipelines must be calculated based on “plug flow” by dividing the internal volume of the pipe by the maximum hourly flow rate through that pipe. Disinfectant contact time within mixing basins and storage reservoirs must be determined by tracer studies or an equivalent demonstration.

Disinfection means a process which inactivates pathogenic organisms in water by chemical oxidants or equivalent agents.

Disinfection profile is a summary of Giardia lamblia inactivation through the treatment plant. The procedure for developing a disinfection profile is contained in § 141.172 (Disinfection profiling and benchmarking) in subpart P and §§ 141.530-141.536 (Disinfection profile) in subpart T of this part.

Domestic or other non-distribution system plumbing problem means a coliform contamination problem in a public water system with more than one service connection that is limited to the specific service connection from which the coliform-positive sample was taken.

Dose equivalent means the product of the absorbed dose from ionizing radiation and such factors as account for differences in biological effectiveness due to the type of radiation and its distribution in the body as specified by the International Commission on Radiological Units and Measurements (ICRU).

Dual sample set is a set of two samples collected at the same time and same location, with one sample analyzed for TTHM and the other sample analyzed for HAA5. Dual sample sets are collected for the purposes of conducting an IDSE under subpart U of this part and determining compliance with the TTHM and HAA5 MCLs under subpart V of this part.

Effective corrosion inhibitor residual, for the purpose of subpart I of this part only, means a concentration sufficient to form a passivating film on the interior walls of a pipe.

Enhanced coagulation means the addition of sufficient coagulant for improved removal of disinfection byproduct precursors by conventional filtration treatment.

Enhanced softening means the improved removal of disinfection byproduct precursors by precipitative softening.

Filter profile is a graphical representation of individual filter performance, based on continuous turbidity measurements or total particle counts versus time for an entire filter run, from startup to backwash inclusively, that includes an assessment of filter performance while another filter is being backwashed.

Filtration means a process for removing particulate matter from water by passage through porous media.

Finished water is water that is introduced into the distribution system of a public water system and is intended for distribution and consumption without further treatment, except as treatment necessary to maintain water quality in the distribution system (e.g., booster disinfection, addition of corrosion control chemicals).

First draw sample means a one-liter sample of tap water, collected in accordance with § 141.86(b)(2), that has been standing in plumbing pipes at least 6 hours and is collected without flushing the tap.

Flocculation means a process to enhance agglomeration or collection of smaller floc particles into larger, more easily settleable particles through gentle stirring by hydraulic or mechanical means.

Flowing stream is a course of running water flowing in a definite channel.

GAC10 means granular activated carbon filter beds with an empty-bed contact time of 10 minutes based on average daily flow and a carbon reactivation frequency of every 180 days, except that the reactivation frequency for GAC10 used as a best available technology for compliance with subpart V MCLs under § 141.64(b)(2) shall be 120 days.

GAC20 means granular activated carbon filter beds with an empty-bed contact time of 20 minutes based on average daily flow and a carbon reactivation frequency of every 240 days.

Ground water under the direct influence of surface water (GWUDI) means any water beneath the surface of the ground with significant occurrence of insects or other macroorganisms, algae, or large-diameter pathogens such as Giardia lamblia or Cryptosporidium, or significant and relatively rapid shifts in water characteristics such as turbidity, temperature, conductivity, or pH which closely correlate to climatological or surface water conditions. Direct influence must be determined for individual sources in accordance with criteria established by the State. The State determination of direct influence may be based on site-specific measurements of water quality and/or documentation of well construction characteristics and geology with field evaluation.

Gross alpha particle activity means the total radioactivity due to alpha particle emission as inferred from measurements on a dry sample.

Gross beta particle activity means the total radioactivity due to beta particle emission as inferred from measurements on a dry sample.

Haloacetic acids (five) (HAA5) mean the sum of the concentrations in milligrams per liter of the haloacetic acid compounds (monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid), rounded to two significant figures after addition.

Halogen means one of the chemical elements chlorine, bromine or iodine.

Initial compliance period means the first full three-year compliance period which begins at least 18 months after promulgation, except for contaminants listed at § 141.61(a) (19)-(21), (c) (19)-(33), and § 141.62(b) (11)-(15), initial compliance period means the first full three-year compliance period after promulgation for systems with 150 or more service connections (January 1993-December 1995), and first full three-year compliance period after the effective date of the regulation (January 1996-December 1998) for systems having fewer than 150 service connections.

Lake/reservoir refers to a natural or man made basin or hollow on the Earth's surface in which water collects or is stored that may or may not have a current or single direction of flow.

Large water system, for the purpose of subpart I of this part only, means a water system that serves more than 50,000 persons.

Lead service line means a service line made of lead which connects the water main to the building inlet and any lead pigtail, gooseneck or other fitting which is connected to such lead line.

Legionella means a genus of bacteria, some species of which have caused a type of pneumonia called Legionnaires Disease.

Level 1 assessment is an evaluation to identify the possible presence of sanitary defects, defects in distribution system coliform monitoring practices, and (when possible) the likely reason that the system triggered the assessment. It is conducted by the system operator or owner. Minimum elements include review and identification of atypical events that could affect distributed water quality or indicate that distributed water quality was impaired; changes in distribution system maintenance and operation that could affect distributed water quality (including water storage); source and treatment considerations that bear on distributed water quality, where appropriate (e.g., whether a ground water system is disinfected); existing water quality monitoring data; and inadequacies in sample sites, sampling protocol, and sample processing. The system must conduct the assessment consistent with any State directives that tailor specific assessment elements with respect to the size and type of the system and the size, type, and characteristics of the distribution system.

Level 2 assessment is an evaluation to identify the possible presence of sanitary defects, defects in distribution system coliform monitoring practices, and (when possible) the likely reason that the system triggered the assessment. A Level 2 assessment provides a more detailed examination of the system (including the system's monitoring and operational practices) than does a Level 1 assessment through the use of more comprehensive investigation and review of available information, additional internal and external resources, and other relevant practices. It is conducted by an individual approved by the State, which may include the system operator. Minimum elements include review and identification of atypical events that could affect distributed water quality or indicate that distributed water quality was impaired; changes in distribution system maintenance and operation that could affect distributed water quality (including water storage); source and treatment considerations that bear on distributed water quality, where appropriate (e.g., whether a ground water system is disinfected); existing water quality monitoring data; and inadequacies in sample sites, sampling protocol, and sample processing. The system must conduct the assessment consistent with any State directives that tailor specific assessment elements with respect to the size and type of the system and the size, type, and characteristics of the distribution system. The system must comply with any expedited actions or additional actions required by the State in the case of an E. coli MCL violation.

Locational running annual average (LRAA) is the average of sample analytical results for samples taken at a particular monitoring location during the previous four calendar quarters.

Man-made beta particle and photon emitters means all radionuclides emitting beta particles and/or photons listed in Maximum Permissible Body Burdens and Maximum Permissible Concentration of Radionuclides in Air or Water for Occupational Exposure, NBS Handbook 69, except the daughter products of thorium-232, uranium-235 and uranium-238.

Maximum contaminant level means the maximum permissable level of a contaminant in water which is delivered to any user of a public water system.

Maximum contaminant level goal or MCLG means the maximum level of a contaminant in drinking water at which no known or anticipated adverse effect on the health of persons would occur, and which allows an adequate margin of safety. Maximum contaminant level goals are nonenforceable health goals.

Maximum residual disinfectant level (MRDL) means a level of a disinfectant added for water treatment that may not be exceeded at the consumer's tap without an unacceptable possibility of adverse health effects. For chlorine and chloramines, a PWS is in compliance with the MRDL when the running annual average of monthly averages of samples taken in the distribution system, computed quarterly, is less than or equal to the MRDL. For chlorine dioxide, a PWS is in compliance with the MRDL when daily samples are taken at the entrance to the distribution system and no two consecutive daily samples exceed the MRDL. MRDLs are enforceable in the same manner as maximum contaminant levels under Section 1412 of the Safe Drinking Water Act. There is convincing evidence that addition of a disinfectant is necessary for control of waterborne microbial contaminants. Notwithstanding the MRDLs listed in § 141.65, operators may increase residual disinfectant levels of chlorine or chloramines (but not chlorine dioxide) in the distribution system to a level and for a time necessary to protect public health to address specific microbiological contamination problems caused by circumstances such as distribution line breaks, storm runoff events, source water contamination, or cross-connections.

Maximum residual disinfectant level goal (MRDLG) means the maximum level of a disinfectant added for water treatment at which no known or anticipated adverse effect on the health of persons would occur, and which allows an adequate margin of safety. MRDLGs are nonenforceable health goals and do not reflect the benefit of the addition of the chemical for control of waterborne microbial contaminants.

Maximum Total Trihalomethane Potential (MTP) means the maximum concentration of total trihalomethanes produced in a given water containing a disinfectant residual after 7 days at a temperature of 25 °C or above.

Medium-size water system, for the purpose of subpart I of this part only, means a water system that serves greater than 3,300 and less than or equal to 50,000 persons.

Membrane filtration is a pressure or vacuum driven separation process in which particulate matter larger than 1 micrometer is rejected by an engineered barrier, primarily through a size-exclusion mechanism, and which has a measurable removal efficiency of a target organism that can be verified through the application of a direct integrity test. This definition includes the common membrane technologies of microfiltration, ultrafiltration, nanofiltration, and reverse osmosis.

Near the first service connection means at one of the 20 percent of all service connections in the entire system that are nearest the water supply treatment facility, as measured by water transport time within the distribution system.

Non-community water system means a public water system that is not a community water system. A non-community water system is either a “transient non-community water system (TWS)” or a “non-transient non-community water system (NTNCWS).”

Non-transient non-community water system or NTNCWS means a public water system that is not a community water system and that regularly serves at least 25 of the same persons over 6 months per year.

Optimal corrosion control treatment, for the purpose of subpart I of this part only, means the corrosion control treatment that minimizes the lead and copper concentrations at users' taps while insuring that the treatment does not cause the water system to violate any national primary drinking water regulations.

Performance evaluation sample means a reference sample provided to a laboratory for the purpose of demonstrating that the laboratory can successfully analyze the sample within limits of performance specified by the Agency. The true value of the concentration of the reference material is unknown to the laboratory at the time of the analysis.

Person means an individual; corporation; company; association; partnership; municipality; or State, Federal, or tribal agency.

Picocurie (pCi) means the quantity of radioactive material producing 2.22 nuclear transformations per minute.

Plant intake refers to the works or structures at the head of a conduit through which water is diverted from a source (e.g., river or lake) into the treatment plant.

Point of disinfectant application is the point where the disinfectant is applied and water downstream of that point is not subject to recontamination by surface water runoff.

Point-of-entry treatment device (POE) is a treatment device applied to the drinking water entering a house or building for the purpose of reducing contaminants in the drinking water distributed throughout the house or building.

Point-of-use treatment device (POU) is a treatment device applied to a single tap used for the purpose of reducing contaminants in drinking water at that one tap.

Presedimentation is a preliminary treatment process used to remove gravel, sand and other particulate material from the source water through settling before the water enters the primary clarification and filtration processes in a treatment plant.

Public water system means a system for the provision to the public of water for human consumption through pipes or, after August 5, 1998, other constructed conveyances, if such system has at least fifteen service connections or regularly serves an average of at least twenty-five individuals daily at least 60 days out of the year. Such term includes: any collection, treatment, storage, and distribution facilities under control of the operator of such system and used primarily in connection with such system; and any collection or pretreatment storage facilities not under such control which are used primarily in connection with such system. Such term does not include any “special irrigation district.” A public water system is either a “community water system” or a “noncommunity water system.”

Rem means the unit of dose equivalent from ionizing radiation to the total body or any internal organ or organ system. A “millirem (mrem)” is1/1000 of a rem.

Repeat compliance period means any subsequent compliance period after the initial compliance period.

Residual disinfectant concentration (“C” in CT calculations) means the concentration of disinfectant measured in mg/l in a representative sample of water.

Sanitary defect is a defect that could provide a pathway of entry for microbial contamination into the distribution system or that is indicative of a failure or imminent failure in a barrier that is already in place.

Sanitary survey means an onsite review of the water source, facilities, equipment, operation and maintenance of a public water system for the purpose of evaluating the adequacy of such source, facilities, equipment, operation and maintenance for producing and distributing safe drinking water.

Seasonal system is a non-community water system that is not operated as a public water system on a year-round basis and starts up and shuts down at the beginning and end of each operating season.

Sedimentation means a process for removal of solids before filtration by gravity or separation.

Service connection, as used in the definition of public water system, does not include a connection to a system that delivers water by a constructed conveyance other than a pipe if:

(1) The water is used exclusively for purposes other than residential uses (consisting of drinking, bathing, and cooking, or other similar uses);

(2) The State determines that alternative water to achieve the equivalent level of public health protection provided by the applicable national primary drinking water regulation is provided for residential or similar uses for drinking and cooking; or

(3) The State determines that the water provided for residential or similar uses for drinking, cooking, and bathing is centrally treated or treated at the point of entry by the provider, a pass-through entity, or the user to achieve the equivalent level of protection provided by the applicable national primary drinking water regulations.

Service line sample means a one-liter sample of water collected in accordance with § 141.86(b)(3), that has been standing for at least 6 hours in a service line.

Single family structure, for the purpose of subpart I of this part only, means a building constructed as a single-family residence that is currently used as either a residence or a place of business.

Slow sand filtration means a process involving passage of raw water through a bed of sand at low velocity (generally less than 0.4 m/h) resulting in substantial particulate removal by physical and biological mechanisms.

Small water system, for the purpose of subpart I of this part only, means a water system that serves 3,300 persons or fewer.

Special irrigation district means an irrigation district in existence prior to May 18, 1994 that provides primarily agricultural service through a piped water system with only incidental residential or similar use where the system or the residential or similar users of the system comply with the exclusion provisions in section 1401(4)(B)(i)(II) or (III).

Standard sample means the aliquot of finished drinking water that is examined for the presence of coliform bacteria.

State means the agency of the State or Tribal government which has jurisdiction over public water systems. During any period when a State or Tribal government does not have primary enforcement responsibility pursuant to section 1413 of the Act, the term “State” means the Regional Administrator, U.S. Environmental Protection Agency.

Subpart H systems means public water systems using surface water or ground water under the direct influence of surface water as a source that are subject to the requirements of subpart H of this part.

Supplier of water means any person who owns or operates a public water system.

Surface water means all water which is open to the atmosphere and subject to surface runoff.

SUVA means Specific Ultraviolet Absorption at 254 nanometers (nm), an indicator of the humic content of water. It is a calculated parameter obtained by dividing a sample's ultraviolet absorption at a wavelength of 254 nm (UV254) (in m= 1) by its concentration of dissolved organic carbon (DOC) (in mg/L).

System with a single service connection means a system which supplies drinking water to consumers via a single service line.

Too numerous to count means that the total number of bacterial colonies exceeds 200 on a 47-mm diameter membrane filter used for coliform detection.

Total Organic Carbon (TOC) means total organic carbon in mg/L measured using heat, oxygen, ultraviolet irradiation, chemical oxidants, or combinations of these oxidants that convert organic carbon to carbon dioxide, rounded to two significant figures.

Total trihalomethanes (TTHM) means the sum of the concentration in milligrams per liter of the trihalomethane compounds (trichloromethane [chloroform], dibromochloromethane, bromodichloromethane and tribromomethane [bromoform]), rounded to two significant figures.

Transient non-community water system or TWS means a non-community water system that does not regularly serve at least 25 of the same persons over six months per year.

Trihalomethane (THM) means one of the family of organic compounds, named as derivatives of methane, wherein three of the four hydrogen atoms in methane are each substituted by a halogen atom in the molecular structure.

Two-stage lime softening is a process in which chemical addition and hardness precipitation occur in each of two distinct unit clarification processes in series prior to filtration.

Uncovered finished water storage facility is a tank, reservoir, or other facility used to store water that will undergo no further treatment to reduce microbial pathogens except residual disinfection and is directly open to the atmosphere.

Virus means a virus of fecal origin which is infectious to humans by waterborne transmission.

Waterborne disease outbreak means the significant occurrence of acute infectious illness, epidemiologically associated with the ingestion of water from a public water system which is deficient in treatment, as determined by the appropriate local or State agency.

Wholesale system is a public water system that treats source water as necessary to produce finished water and then delivers some or all of that finished water to another public water system. Delivery may be through a direct connection or through the distribution system of one or more consecutive systems.

[40 FR 59570, Dec. 24, 1975]

§ 141.3 Coverage.

This part shall apply to each public water system, unless the public water system meets all of the following conditions:

(a) Consists only of distribution and storage facilities (and does not have any collection and treatment facilities);

(b) Obtains all of its water from, but is not owned or operated by, a public water system to which such regulations apply:

(c) Does not sell water to any person; and

(d) Is not a carrier which conveys passengers in interstate commerce.

§ 141.4 Variances and exemptions.

(a) Variances or exemptions from certain provisions of these regulations may be granted pursuant to sections 1415 and 1416 of the Act and subpart K of part 142 of this chapter (for small system variances) by the entity with primary enforcement responsibility, except that variances or exemptions from the MCLs for total coliforms and E. coli and variances from any of the treatment technique requirements of subpart H of this part may not be granted.

(b) EPA has stayed the effective date of this section relating to the total coliform MCL of § 141.63(a) for systems that demonstrate to the State that the violation of the total coliform MCL is due to a persistent growth of total coliforms in the distribution system rather than fecal or pathogenic contamination, a treatment lapse or deficiency, or a problem in the operation or maintenance of the distribution system. This is stayed until March 31, 2016, at which time the total coliform MCL is no longer effective.

Note to paragraph (a):

As provided in § 142.304(a), small system variances are not available for rules addressing microbial contaminants, which would include subparts H, P, S, T, W, and Y of this part.

[78 FR 10346, Feb. 13, 2013]

§ 141.5 Siting requirements.

Before a person may enter into a financial commitment for or initiate construction of a new public water system or increase the capacity of an existing public water system, he shall notify the State and, to the extent practicable, avoid locating part or all of the new or expanded facility at a site which:

(a) Is subject to a significant risk from earthquakes, floods, fires or other disasters which could cause a breakdown of the public water system or a portion thereof; or

(b) Except for intake structures, is within the floodplain of a 100-year flood or is lower than any recorded high tide where appropriate records exist. The U.S. Environmental Protection Agency will not seek to override land use decisions affecting public water systems siting which are made at the State or local government levels.

§ 141.6 Effective dates.

(a) Except as provided in paragraphs (b) through (k) of this section, and in § 141.80(a)(2), the regulations set forth in this part shall take effect on June 24, 1977.

(b) The regulations for total trihalomethanes set forth in § 141.12(c) shall take effect 2 years after the date of promulgation of these regulations for community water systems serving 75,000 or more individuals, and 4 years after the date of promulgation for communities serving 10,000 to 74,999 individuals.

(c) The regulations set forth in §§ 141.11(d); 141.21(a), (c) and (i); 141.22(a) and (e); 141.23(a)(3) and (a)(4); 141.23(f); 141.24(e) and (f); 141.25(e); 141.27(a); 141.28(a) and (b); 141.31(a), (d) and (e); 141.32(b)(3); and 141.32(d) shall take effect immediately upon promulgation.

(d) The regulations set forth in § 141.41 shall take effect 18 months from the date of promulgation. Suppliers must complete the first round of sampling and reporting within 12 months following the effective date.

(e) The regulations set forth in § 141.42 shall take effect 18 months from the date of promulgation. All requirements in § 141.42 must be completed within 12 months following the effective date.

(f) The regulations set forth in § 141.11(c) and § 141.23(g) are effective May 2, 1986. Section 141.23(g)(4) is effective October 2, 1987.

(g) The regulations contained in § 141.6, paragraph (c) of the table in 141.12, and 141.62(b)(1) are effective July 1, 1991. The regulations contained in §§ 141.11(b), 141.23, 141.24, 142.57(b), 143.4(b)(12) and (b)(13), are effective July 30, 1992. The regulations contained in the revisions to §§ 141.32(e) (16), (25) through (27) and (46); 141.61(c)(16); and 141.62(b)(3) are effective January 1, 1993. The effective date of regulations contained in § 141.61(c) (2), (3), and (4) is postponed.

(h) Regulations for the analytic methods listed at § 141.23(k)(4) for measuring antimony, beryllium, cyanide, nickel, and thallium are effective August 17, 1992. Regulations for the analytic methods listed at § 141.24(f)(16) for dichloromethane, 1,2,4-trichlorobenzene, and 1,1,2-trichloroethane are effective August 17, 1992. Regulations for the analytic methods listed at § 141.24(h)(12) for measuring dalapon, dinoseb, diquat, endothall, endrin, glyphosate, oxamyl, picloram, simazine, benzo(a)pyrene, di(2-ethylhexyl)adipate, di(2-ethylhexyl)phthalate, hexachlorobenzene, hexachlorocyclopentadiene, and 2,3,7,8-TCDD are effective August 17, 1992. The revision to § 141.12(a) promulgated on July 17, 1992 is effective on August 17, 1992.

(i) [Reserved]

(j) The arsenic maximum contaminant levels (MCL) listed in § 141.62 is effective for the purpose of compliance on January 23, 2006. Requirements relating to arsenic set forth in §§ 141.23(i)(4), 141.23(k)(3) introductory text, 141.23(k)(3)(ii), 141.51(b), 141.62(b), 141.62(b)(16), 141.62(c), 141.62(d), and 142.62(b) revisions in Appendix A of subpart O for the consumer confidence rule, and Appendices A and B of subpart Q for the public notification rule are effective for the purpose of compliance on January 23, 2006. However, the consumer confidence rule reporting requirements relating to arsenic listed in § 141.154(b) and (f) are effective for the purpose of compliance on February 22, 2002.

(k) Regulations set forth in §§ 141.23(i)(1), 141.23(i)(2), 141.24(f)(15), 141.24(f)(22), 141.24(h)(11), 141.24(h)(20), 142.16(e), 142.16(j), and 142.16(k) are effective for the purpose of compliance on January 22, 2004.

[44 FR 68641, Nov. 29, 1979, as amended at 45 FR 57342, Aug. 27, 1980; 47 FR 10998, Mar. 12, 1982; 51 FR 11410, Apr. 2, 1986; 56 FR 30274, July 1, 1991; 57 FR 22178, May 27, 1992; 57 FR 31838, July 17, 1992; 59 FR 34322, July 1, 1994; 61 FR 24368, May 14, 1996; 66 FR 7061, Jan. 22, 2001; 66 FR 28350, May 22, 2001]

Subpart B - Maximum Contaminant Levels
§ 141.11 Maximum contaminant levels for inorganic chemicals.

(a) The maximum contaminant level for arsenic applies only to community water systems. The analyses and determination of compliance with the 0.05 milligrams per liter maximum contaminant level for arsenic use the requirements of § 141.23.

(b) The maximum contaminant level for arsenic is 0.05 milligrams per liter for community water systems until January 23, 2006.

(c) [Reserved]

(d) At the discretion of the State, nitrate levels not to exceed 20 mg/l may be allowed in a non-community water system if the supplier of water demonstrates to the satisfaction of the State that:

(1) Such water will not be available to children under 6 months of age; and

(2) The non-community water system is meeting the public notification requirements under § 141.209, including continuous posting of the fact that nitrate levels exceed 10 mg/l and the potential health effects of exposure; and

(3) Local and State public health authorities will be notified annually of nitrate levels that exceed 10 mg/l; and

(4) No adverse health effects shall result.

[40 FR 59570, Dec. 24, 1975, as amended at 45 FR 57342, Aug. 27, 1980; 47 FR 10998, Mar. 12, 1982; 51 FR 11410, Apr. 2, 1986; 56 FR 3578, Jan. 30, 1991; 56 FR 26548, June 7, 1991; 56 FR 30274, July 1, 1991; 56 FR 32113, July 15, 1991; 60 FR 33932, June 29, 1995; 65 FR 26022, May 4, 2000; 66 FR 7061, Jan. 22, 2001]

§ 141.12 [Reserved]
§ 141.13 Maximum contaminant levels for turbidity.

The maximum contaminant levels for turbidity are applicable to both community water systems and non-community water systems using surface water sources in whole or in part. The maximum contaminant levels for turbidity in drinking water, measured at a representative entry point(s) to the distribution system, are:

(a) One turbidity unit (TU), as determined by a monthly average pursuant to § 141.22, except that five or fewer turbidity units may be allowed if the supplier of water can demonstrate to the State that the higher turbidity does not do any of the following:

(1) Interfere with disinfection;

(2) Prevent maintenance of an effective disinfectant agent throughout the distribution system; or

(3) Interfere with microbiological determinations.

(b) Five turbidity units based on an average for two consecutive days pursuant to § 141.22.

[40 FR 59570, Dec. 24, 1975]

Subpart C - Monitoring and Analytical Requirements
§ 141.21 Coliform sampling.

(a) Routine monitoring.

(1) Public water systems must collect total coliform samples at sites which are representative of water throughout the distribution system according to a written sample siting plan. These plans are subject to State review and revision.

(2) The monitoring frequency for total coliforms for community water systems is based on the population served by the system, as follows:

Total Coliform Monitoring Frequency for Community Water Systems

Population served Minimum number of samples per month
25 to 1,0001 1
1,001 to 2,500 2
2,501 to 3,300 3
3,301 to 4,100 4
4,101 to 4,900 5
4,901 to 5,800 6
5,801 to 6,700 7
6,701 to 7,600 8
7,601 to 8,500 9
8,501 to 12,900 10
12,901 to 17,200 15
17,201 to 21,500 20
21,501 to 25,000 25
25,001 to 33,000 30
33,001 to 41,000 40
41,001 to 50,000 50
50,001 to 59,000 60
59,001 to 70,000 70
70,001 to 83,000 80
83,001 to 96,000 90
96,001 to 130,000 100
130,001 to 220,000 120
220,001 to 320,000 150
320,001 to 450,000 180
450,001 to 600,000 210
600,001 to 780,000 240
780,001 to 970,000 270
970,001 to 1,230,000 300
1,230,001 to 1,520,000 330
1,520,001 to 1,850,000 360
1,850,001 to 2,270,000 390
2,270,001 to 3,020,000 420
3,020,001 to 3,960,000 450
3,960,001 or more 480

If a community water system serving 25 to 1,000 persons has no history of total coliform contamination in its current configuration and a sanitary survey conducted in the past five years shows that the system is supplied solely by a protected groundwater source and is free of sanitary defects, the State may reduce the monitoring frequency specified above, except that in no case may the State reduce the monitoring frequency to less than one sample per quarter. The State must approve the reduced monitoring frequency in writing.

(3) The monitoring frequency for total coliforms for non-community water systems is as follows:

(i) A non-community water system using only ground water (except ground water under the direct influence of surface water, as defined in § 141.2) and serving 1,000 persons or fewer must monitor each calendar quarter that the system provides water to the public, except that the State may reduce this monitoring frequency, in writing, if a sanitary survey shows that the system is free of sanitary defects. Beginning June 29, 1994, the State cannot reduce the monitoring frequency for a non-community water system using only ground water (except ground water under the direct influence of surface water, as defined in § 141.2) and serving 1,000 persons or fewer to less than once/year.

(ii) A non-community water system using only ground water (except ground water under the direct influence of surface water, as defined in § 141.2) and serving more than 1,000 persons during any month must monitor at the same frequency as a like-sized community water system, as specified in paragraph (a)(2) of this section, except the State may reduce this monitoring frequency, in writing, for any month the system serves 1,000 persons or fewer. The State cannot reduce the monitoring frequency to less than once/year. For systems using ground water under the direct influence of surface water, paragraph (a)(3)(iv) of this section applies.

(iii) A non-community water system using surface water, in total or in part, must monitor at the same frequency as a like-sized community water system, as specified in paragraph (a)(2) of this section, regardless of the number of persons it serves.

(iv) A non-community water system using ground water under the direct influence of surface water, as defined in § 141.2, must monitor at the same frequency as a like-sized community water system, as specified in paragraph (a)(2) of this section. The system must begin monitoring at this frequency beginning six months after the State determines that the ground water is under the direct influence of surface water.

(4) The public water system must collect samples at regular time intervals throughout the month, except that a system which uses only ground water (except ground water under the direct influence of surface water, as defined in § 141.2), and serves 4,900 persons or fewer, may collect all required samples on a single day if they are taken from different sites.

(5) A public water system that uses surface water or ground water under the direct influence of surface water, as defined in § 141.2, and does not practice filtration in compliance with Subpart H must collect at least one sample near the first service connection each day the turbidity level of the source water, measured as specified in § 141.74(b)(2), exceeds 1 NTU. This sample must be analyzed for the presence of total coliforms. When one or more turbidity measurements in any day exceed 1 NTU, the system must collect this coliform sample within 24 hours of the first exceedance, unless the State determines that the system, for logistical reasons outside the system's control, cannot have the sample analyzed within 30 hours of collection. Sample results from this coliform monitoring must be included in determining compliance with the MCL for total coliforms in § 141.63.

(6) Special purpose samples, such as those taken to determine whether disinfection practices are sufficient following pipe placement, replacement, or repair, shall not be used to determine compliance with the MCL for total coliforms in § 141.63. Repeat samples taken pursuant to paragraph (b) of this section are not considered special purpose samples, and must be used to determine compliance with the MCL for total coliforms in § 141.63.

(b) Repeat monitoring.

(1) If a routine sample is total coliform-positive, the public water system must collect a set of repeat samples within 24 hours of being notified of the positive result. A system which collects more than one routine sample/month must collect no fewer than three repeat samples for each total coliform-positive sample found. A system which collects one routine sample/month or fewer must collect no fewer than four repeat samples for each total coliform-positive sample found. The State may extend the 24-hour limit on a case-by-case basis if the system has a logistical problem in collecting the repeat samples within 24 hours that is beyond its control. In the case of an extension, the State must specify how much time the system has to collect the repeat samples.

(2) The system must collect at least one repeat sample from the sampling tap where the original total coliform-positive sample was taken, and at least one repeat sample at a tap within five service connections upstream and at least one repeat sample at a tap within five service connections downstream of the original sampling site. If a total coliform-positive sample is at the end of the distribution system, or one away from the end of the distribution system, the State may waive the requirement to collect at least one repeat sample upstream or downstream of the original sampling site.

(3) The system must collect all repeat samples on the same day, except that the State may allow a system with a single service connection to collect the required set of repeat samples over a four-day period or to collect a larger volume repeat sample(s) in one or more sample containers of any size, as long as the total volume collected is at least 400 ml (300 ml for systems which collect more than one routine sample/month).

(4) If one or more repeat samples in the set is total coliform-positive, the public water system must collect an additional set of repeat samples in the manner specified in paragraphs (b) (1)-(3) of this section. The additional samples must be collected within 24 hours of being notified of the positive result, unless the State extends the limit as provided in paragraph (b)(1) of this section. The system must repeat this process until either total coliforms are not detected in one complete set of repeat samples or the system determines that the MCL for total coliforms in § 141.63 has been exceeded and notifies the State.

(5) If a system collecting fewer than five routine samples/month has one or more total coliform-positive samples and the State does not invalidate the sample(s) under paragraph (c) of this section, it must collect at least five routine samples during the next month the system provides water to the public, except that the State may waive this requirement if the conditions of paragraph (b)(5) (i) or (ii) of this section are met. The State cannot waive the requirement for a system to collect repeat samples in paragraphs (b) (1)-(4) of this section.

(i) The State may waive the requirement to collect five routine samples the next month the system provides water to the public if the State, or an agent approved by the State, performs a site visit before the end of the next month the system provides water to the public. Although a sanitary survey need not be performed, the site visit must be sufficiently detailed to allow the State to determine whether additional monitoring and/or any corrective action is needed. The State cannot approve an employee of the system to perform this site visit, even if the employee is an agent approved by the State to perform sanitary surveys.

(ii) The State may waive the requirement to collect five routine samples the next month the system provides water to the public if the State has determined why the sample was total coliform-positive and establishes that the system has corrected the problem or will correct the problem before the end of the next month the system serves water to the public. In this case, the State must document this decision to waive the following month's additional monitoring requirement in writing, have it approved and signed by the supervisor of the State official who recommends such a decision, and make this document available to the EPA and public. The written documentation must describe the specific cause of the total coliform-positive sample and what action the system has taken and/or will take to correct this problem. The State cannot waive the requirement to collect five routine samples the next month the system provides water to the public solely on the grounds that all repeat samples are total coliform-negative. Under this paragraph, a system must still take at least one routine sample before the end of the next month it serves water to the public and use it to determine compliance with the MCL for total coliforms in § 141.63, unless the State has determined that the system has corrected the contamination problem before the system took the set of repeat samples required in paragraphs (b) (1)-(4) of this section, and all repeat samples were total coliform-negative.

(6) After a system collects a routine sample and before it learns the results of the analysis of that sample, if it collects another routine sample(s) from within five adjacent service connections of the initial sample, and the initial sample, after analysis, is found to contain total coliforms, then the system may count the subsequent sample(s) as a repeat sample instead of as a routine sample.

(7) Results of all routine and repeat samples not invalidated by the State must be included in determining compliance with the MCL for total coliforms in § 141.63.

(c) Invalidation of total coliform samples. A total coliform-positive sample invalidated under this paragraph (c) does not count towards meeting the minimum monitoring requirements of this section.

(1) The State may invalidate a total coliform-positive sample only if the conditions of paragraph (c)(1) (i), (ii), or (iii) of this section are met.

(i) The laboratory establishes that improper sample analysis caused the total coliform-positive result.

(ii) The State, on the basis of the results of repeat samples collected as required by paragraphs (b) (1) through (4) of this section, determines that the total coliform-positive sample resulted from a domestic or other non-distribution system plumbing problem. The State cannot invalidate a sample on the basis of repeat sample results unless all repeat sample(s) collected at the same tap as the original total coliform-positive sample are also total coliform-positive, and all repeat samples collected within five service connections of the original tap are total coliform-negative (e.g., a State cannot invalidate a total coliform-positive sample on the basis of repeat samples if all the repeat samples are total coliform-negative, or if the public water system has only one service connection).

(iii) The State has substantial grounds to believe that a total coliform-positive result is due to a circumstance or condition which does not reflect water quality in the distribution system. In this case, the system must still collect all repeat samples required under paragraphs (b) (1)-(4) of this section, and use them to determine compliance with the MCL for total coliforms in § 141.63. To invalidate a total coliform-positive sample under this paragraph, the decision with the rationale for the decision must be documented in writing, and approved and signed by the supervisor of the State official who recommended the decision. The State must make this document available to EPA and the public. The written documentation must state the specific cause of the total coliform-positive sample, and what action the system has taken, or will take, to correct this problem. The State may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.

(2) A laboratory must invalidate a total coliform sample (unless total coliforms are detected) if the sample produces a turbid culture in the absence of gas production using an analytical method where gas formation is examined (e.g., the Multiple-Tube Fermentation Technique), produces a turbid culture in the absence of an acid reaction in the Presence-Absence (P-A) Coliform Test, or exhibits confluent growth or produces colonies too numerous to count with an analytical method using a membrane filter (e.g., Membrane Filter Technique). If a laboratory invalidates a sample because of such interference, the system must collect another sample from the same location as the original sample within 24 hours of being notified of the interference problem, and have it analyzed for the presence of total coliforms. The system must continue to re-sample within 24 hours and have the samples analyzed until it obtains a valid result. The State may waive the 24-hour time limit on a case-by-case basis.

(d) Sanitary surveys.

(1)

(i) Public water systems which do not collect five or more routine samples/month must undergo an initial sanitary survey by June 29, 1994, for community public water systems and June 29, 1999, for non-community water systems. Thereafter, systems must undergo another sanitary survey every five years, except that non-community water systems using only protected and disinfected ground water, as defined by the State, must undergo subsequent sanitary surveys at least every ten years after the initial sanitary survey. The State must review the results of each sanitary survey to determine whether the existing monitoring frequency is adequate and what additional measures, if any, the system needs to undertake to improve drinking water quality.

(ii) In conducting a sanitary survey of a system using ground water in a State having an EPA-approved wellhead protection program under section 1428 of the Safe Drinking Water Act, information on sources of contamination within the delineated wellhead protection area that was collected in the course of developing and implementing the program should be considered instead of collecting new information, if the information was collected since the last time the system was subject to a sanitary survey.

(2) Sanitary surveys must be performed by the State or an agent approved by the State. The system is responsible for ensuring the survey takes place.

(3) Sanitary surveys conducted by the State under the provisions of § 142.16(o)(2) of this chapter may be used to meet the sanitary survey requirements of this section.

(e) Fecal coliforms/Escherichia coli (E. coli) testing.

(1) If any routine or repeat sample is total coliform-positive, the system must analyze that total coliform-positive culture medium to determine if fecal coliforms are present, except that the system may test for E. coli in lieu of fecal coliforms. If fecal coliforms or E. coli are present, the system must notify the State by the end of the day when the system is notified of the test result, unless the system is notified of the result after the State office is closed, in which case the system must notify the State before the end of the next business day.

(2) The State has the discretion to allow a public water system, on a case-by-case basis, to forgo fecal coliform or E. coli testing on a total coliform-positive sample if that system assumes that the total coliform-positive sample is fecal coliform-positive or E. coli-positive. Accordingly, the system must notify the State as specified in paragraph (e)(1) of this section and the provisions of § 141.63(b) apply.

(f) Analytical methodology.

(1) The standard sample volume required for total coliform analysis, regardless of analytical method used, is 100 ml.

(2) Public water systems need only determine the presence or absence of total coliforms; a determination of total coliform density is not required.

(3) Public water systems must conduct total coliform analyses in accordance with one of the analytical methods in the following table or one of the alternative methods listed in appendix A to subpart C of this part.

Organism Methodology12 Citation1
Total Coliforms2 Total Coliform Fermentation Technique3 4 5 9221A, B.
Total Coliform Membrane Filter Technique6 9222A, B, C.
Presence-Absence (P-A) Coliform Test5 7 9221D.
ONPG-MUG Test8 9223.
Colisure Test.9
E*Colite ® Test.10
m-ColiBlue24 ® Test.11
Readycult ® Coliforms 100 Presence/Absence Test.13
Membrane Filter Technique using Chromocult ® Coliform Agar.14
Colitag ® Test.15

(4) [Reserved]

(5) Public water systems must conduct fecal coliform analysis in accordance with the following procedure. When the MTF Technique or Presence-Absence (PA) Coliform Test is used to test for total coliforms, shake the lactose-positive presumptive tube or P-A vigorously and transfer the growth with a sterile 3-mm loop or sterile applicator stick into brilliant green lactose bile broth and EC medium to determine the presence of total and fecal coliforms, respectively. For EPA-approved analytical methods which use a membrane filter, transfer the total coliform-positive culture by one of the following methods: remove the membrane containing the total coliform colonies from the substrate with a sterile forceps and carefully curl and insert the membrane into a tube of EC medium (the laboratory may first remove a small portion of selected colonies for verification), swab the entire membrane filter surface with a sterile cotton swab and transfer the inoculum to EC medium (do not leave the cotton swab in the EC medium), or inoculate individual total coliform-positive colonies into EC Medium. Gently shake the inoculated tubes of EC medium to insure adequate mixing and incubate in a waterbath at 44.5 ±0.2 °C for 24 ±2 hours. Gas production of any amount in the inner fermentation tube of the EC medium indicates a positive fecal coliform test. The preparation of EC medium is described in Method 9221E (paragraph 1a) in Standard Methods for the Examination of Water and Wastewater, 18th edition (1992), 19th edition (1995), and 20th edition (1998); the cited method in any one of these three editions may be used. Public water systems need only determine the presence or absence of fecal coliforms; a determination of fecal coliform density is not required.

(6) Public water systems must conduct analysis of Escherichia coli in accordance with one of the following analytical methods or one of the alternative methods listed in appendix A to subpart C of this part.

(i) EC medium supplemented with 50 µg/mL of 4-methylumbelliferyl-beta-D-glucuronide (MUG) (final concentration), as described in Method 9222G in Standard Methods for the Examination of Water and Wastewater, 19th edition (1995) and 20th edition (1998). Either edition may be used. Alternatively, the 18th edition (1992) may be used if at least 10 mL of EC medium, as described in paragraph (f)(5) of this section, is supplemented with 50 µg/mL of MUG before autoclaving. The inner inverted fermentation tube may be omitted. If the 18th edition is used, apply the procedure in paragraph (f)(5) of this section for transferring a total coliform-positive culture to EC medium supplemented with MUG, incubate the tube at 44.5 ±0.2 °C for 24 ±2 hours, and then observe fluorescence with an ultraviolet light (366 nm) in the dark. If fluorescence is visible, E. coli are present.

(ii) Nutrient agar supplemented with 100 µg/mL of 4-methylumbelliferyl-beta-D-glucuronide (MUG) (final concentration), as described in Method 9222G in Standard Methods for the Examination of Water and Wastewater, 19th edition (1995) and 20th edition (1998). Either edition may be used for determining if a total coliform-positive sample, as determined by a membrane filter technique, contains E. coli. Alternatively, the 18th edition (1992) may be used if the membrane filter containing a total coliform-positive colony(ies) is transferred to nutrient agar, as described in Method 9221B (paragraph 3) of Standard Methods (18th edition), supplemented with 100 µg/mL of MUG. If the 18th edition is used, incubate the agar plate at 35 °C for 4 hours and then observe the colony(ies) under ultraviolet light (366 nm) in the dark for fluorescence. If fluorescence is visible, E. coli are present.

(iii) Minimal Medium ONPG-MUG (MMO-MUG) Test, as set forth in the article “National Field Evaluation of a Defined Substrate Method for the Simultaneous Detection of Total Coliforms and Escherichia coli from Drinking Water: Comparison with Presence-Absence Techniques” (Edberg et al.), Applied and Environmental Microbiology, Volume 55, pp. 1003-1008, April 1989. (Note: The Autoanalysis Colilert System is an MMO-MUG test). If the MMO-MUG test is total coliform-positive after a 24-hour incubation, test the medium for fluorescence with a 366-nm ultraviolet light (preferably with a 6-watt lamp) in the dark. If fluorescence is observed, the sample is E. coli-positive. If fluorescence is questionable (cannot be definitively read) after 24 hours incubation, incubate the culture for an additional four hours (but not to exceed 28 hours total), and again test the medium for fluorescence. The MMO-MUG Test with hepes buffer in lieu of phosphate buffer is the only approved formulation for the detection of E. coli.

(iv) The Colisure Test. A description of the Colisure Test may be obtained from the Millipore Corporation, Technical Services Department, 80 Ashby Road, Bedford, MA 01730.

(v) The membrane filter method with MI agar, a description of which is cited in footnote 6 to the table in paragraph (f)(3) of this section.

(vi) E*Colite ® Test, a description of which is cited in footnote 10 to the table at paragraph (f)(3) of this section.

(vii) m-ColiBlue24 ® Test, a description of which is cited in footnote 11 to the table in paragraph (f)(3) of this section.

(viii) Readycult ® Coliforms 100 Presence/Absence Test, a description of which is cited in footnote 13 to the table at paragraph (f)(3) of this section.

(ix) Membrane Filter Technique using Chromocult ® Coliform Agar, a description of which is cited in footnote 14 to the table at paragraph (f)(3) of this section.

(x) Colitag ®, a description of which is cited in footnote 15 to the table at paragraph (f)(3) of this section.

(7) As an option to paragraph (f)(6)(iii) of this section, a system with a total coliform-positive, MUG-negative, MMO-MUG test may further analyze the culture for the presence of E. coli by transferring a 0.1 ml, 28-hour MMO-MUG culture to EC Medium + MUG with a pipet. The formulation and incubation conditions of EC Medium + MUG, and observation of the results are described in paragraph (f)(6)(i) of this section.

(8) The following materials are incorporated by reference in this section with the approval of the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the analytical methods cited in Standard Methods for the Examination of Water and Wastewater (18th, 19th, and 20th editions) may be obtained from the American Public Health Association et al.; 1015 Fifteenth Street, NW., Washington, DC 20005-2605. Copies of the MMO-MUG Test, as set forth in the article “National Field Evaluation of a Defined Substrate Method for the Simultaneous Enumeration of Total Coliforms and Escherichia coli from Drinking Water: Comparison with the Standard Multiple Tube Fermentation Method” (Edberg et al.) may be obtained from the American Water Works Association Research Foundation, 6666 West Quincy Avenue, Denver, CO 80235. Copies of the MMO-MUG Test as set forth in the article “National Field Evaluation of a Defined Substrate Method for the Simultaneous Enumeration of Total Coliforms and Escherichia coli from Drinking Water: Comparison with the Standard Multiple Tube Fermentation Method” (Edberg et al.) may be obtained from the American Water Works Association Research Foundation, 6666 West Quincy Avenue, Denver, CO 80235. A description of the Colisure Test may be obtained from the Millipore Corp., Technical Services Department, 80 Ashby Road, Bedford, MA 01730. Copies may be inspected at EPA's Drinking Water Docket; 401 M St., SW.; Washington, DC 20460, or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

(g) Response to violation.

(1) A public water system which has exceeded the MCL for total coliforms in § 141.63 must report the violation to the State no later than the end of the next business day after it learns of the violation, and notify the public in accordance with subpart Q.

(2) A public water system which has failed to comply with a coliform monitoring requirement, including the sanitary survey requirement, must report the monitoring violation to the State within ten days after the system discovers the violation, and notify the public in accordance with subpart Q.

(h) The provisions of paragraphs (a) and (d) of this section are applicable until March 31, 2016. The provisions of paragraphs (b), (c), (e), (f), and (g) of this section are applicable until all required repeat monitoring under paragraph (b) of this section and fecal coliform or E. coli testing under paragraph (e) of this section that was initiated by a total coliform-positive sample taken before April 1, 2016 is completed, as well as analytical method, reporting, recordkeeping, public notification, and consumer confidence report requirements associated with that monitoring and testing. Beginning April 1, 2016, the provisions of subpart Y of this part are applicable, with systems required to begin regular monitoring at the same frequency as the system-specific frequency required on March 31, 2016.

[54 FR 27562, June 29, 1989]

§ 141.22 Turbidity sampling and analytical requirements.

The requirements in this section apply to unfiltered systems until December 30, 1991, unless the State has determined prior to that date, in writing pursuant to section 1412(b)(7)(iii), that filtration is required. The requirements in this section apply to filtered systems until June 29, 1993. The requirements in this section apply to unfiltered systems that the State has determined, in writing pursuant to section 1412(b)(7)(C)(iii), must install filtration, until June 29, 1993, or until filtration is installed, whichever is later.

(a) Samples shall be taken by suppliers of water for both community and non-community water systems at a representative entry point(s) to the water distribution system at least once per day, for the purposes of making turbidity measurements to determine compliance with § 141.13. If the State determines that a reduced sampling frequency in a non-community will not pose a risk to public health, it can reduce the required sampling frequency. The option of reducing the turbidity frequency shall be permitted only in those public water systems that practice disinfection and which maintain an active residual disinfectant in the distribution system, and in those cases where the State has indicated in writing that no unreasonable risk to health existed under the circumstances of this option. Turbidity measurements shall be made as directed in § 141.74(a)(1).

(b) If the result of a turbidity analysis indicates that the maximum allowable limit has been exceeded, the sampling and measurement shall be confirmed by resampling as soon as practicable and preferably within one hour. If the repeat sample confirms that the maximum allowable limit has been exceeded, the supplier of water shall report to the State within 48 hours. The repeat sample shall be the sample used for the purpose of calculating the monthly average. If the monthly average of the daily samples exceeds the maximum allowable limit, or if the average of two samples taken on consecutive days exceeds 5 TU, the supplier of water shall report to the State and notify the public as directed in § 141.31 and subpart Q.

(c) Sampling for non-community water systems shall begin within two years after the effective date of this part.

(d) The requirements of this § 141.22 shall apply only to public water systems which use water obtained in whole or in part from surface sources.

(e) The State has the authority to determine compliance or initiate enforcement action based upon analytical results or other information compiled by their sanctioned representatives and agencies.

[40 FR 59570, Dec. 24, 1975, as amended at 45 FR 57344, Aug. 27, 1980; 47 FR 8998, Mar. 3, 1982; 47 FR 10998, Mar. 12, 1982; 54 FR 27527, June 29, 1989; 59 FR 62466, Dec. 5, 1994; 65 FR 26022, May 4, 2000]

§ 141.23 Inorganic chemical sampling and analytical requirements.

Community water systems shall conduct monitoring to determine compliance with the maximum contaminant levels specified in § 141.62 in accordance with this section. Non-transient, non-community water systems shall conduct monitoring to determine compliance with the maximum contaminant levels specified in § 141.62 in accordance with this section. Transient, non-community water systems shall conduct monitoring to determine compliance with the nitrate and nitrite maximum contaminant levels in §§ 141.11 and 141.62 (as appropriate) in accordance with this section.

(a) Monitoring shall be conducted as follows:

(1) Groundwater systems shall take a minimum of one sample at every entry point to the distribution system which is representative of each well after treatment (hereafter called a sampling point) beginning in the initial compliance period. The system shall take each sample at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant.

(2) Surface water systems shall take a minimum of one sample at every entry point to the distribution system after any application of treatment or in the distribution system at a point which is representative of each source after treatment (hereafter called a sampling point) beginning in the initial compliance period. The system shall take each sample at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant.

Note:

For purposes of this paragraph, surface water systems include systems with a combination of surface and ground sources.

(3) If a system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water is representative of all sources being used).

(4) The State may reduce the total number of samples which must be analyzed by allowing the use of compositing. Composite samples from a maximum of five samples are allowed, provided that the detection limit of the method used for analysis is less than one-fifth of the MCL. Compositing of samples must be done in the laboratory.

(i) If the concentration in the composite sample is greater than or equal to one-fifth of the MCL of any inorganic chemical, then a follow-up sample must be taken within 14 days at each sampling point included in the composite. These samples must be analyzed for the contaminants which exceeded one-fifth of the MCL in the composite sample. Detection limits for each analytical method and MCLs for each inorganic contaminant are the following:

Detection Limits for Inorganic Contaminants

Contaminant MCL (mg/l) Methodology Detection limit (mg/l)
Antimony 0.006 Atomic Absorption; Furnace 0.003
Atomic Absorption; Platform 0.00085
ICP-Mass Spectrometry 0.0004
Hydride-Atomic Absorption 0.001
Arsenic 0.0106 Atomic Absorption; Furnace 0.001
Atomic Absorption; Platform - Stabilized Temperature 0.00057
Atomic Absorption; Gaseous Hydride 0.001
ICP-Mass Spectrometry 0.00148
Asbestos 7 MFL1 Transmission Electron Microscopy 0.01 MFL
Barium 2 Atomic Absorption; furnace technique 0.002
Atomic Absorption; direct aspiration 0.1
Inductively Coupled Plasma 0.002 (0.001)
Beryllium 0.004 Atomic Absorption; Furnace 0.0002
Atomic Absorption; Platform 0.000025
Inductively Coupled Plasma2 0.0003
ICP-Mass Spectrometry 0.0003
Cadmium 0.005 Atomic Absorption; furnace technique 0.0001
Inductively Coupled Plasma 0.001
Chromium 0.1 Atomic Absorption; furnace technique 0.001
Inductively Coupled Plasma 0.007 (0.001)
Cyanide 0.2 Distillation, Spectrophotometric3 0.02
Distillation, Automated, Spectrophotometric3 0.005
Distillation, Amenable, Spectrophotometric4 0.02
Distillation, Selective Electrode3 4 0.05
UV, Distillation, Spectrophotometric9 0.0005
Micro Distillation, Flow Injection, Spectrophotometric3 0.0006
Ligand Exchange with Amperometry4 0.0005
Mercury 0.002 Manual Cold Vapor Technique 0.0002
Automated Cold Vapor Technique 0.0002
Nickel xl Atomic Absorption; Furnace 0.001
Atomic Absorption; Platform 0.00065
Inductively Coupled Plasma2 0.005
ICP-Mass Spectrometry 0.0005
Nitrate 10 (as N) Manual Cadmium Reduction 0.01
Automated Hydrazine Reduction 0.01
Automated Cadmium Reduction 0.05
Ion Selective Electrode 1
Ion Chromatography 0.01
Capillary Ion Electrophoresis 0.076
Nitrite 1 (as N) Spectrophotometric 0.01
Automated Cadmium Reduction 0.05
Manual Cadmium Reduction 0.01
Ion Chromatography 0.004
Capillary Ion Electrophoresis 0.103
Selenium 0.05 Atomic Absorption; furnace 0.002
Atomic Absorption; gaseous hydride 0.002
Thallium 0.002 Atomic Absorption; Furnace 0.001
Atomic Absorption; Platform 0.00075
ICP-Mass Spectrometry 0.0003

(ii) If the population served by the system is >3,300 persons, then compositing may only be permitted by the State at sampling points within a single system. In systems serving ≤3,300 persons, the State may permit compositing among different systems provided the 5-sample limit is maintained.

(iii) If duplicates of the original sample taken from each sampling point used in the composite sample are available, the system may use these instead of resampling. The duplicates must be analyzed and the results reported to the State within 14 days after completing analysis of the composite sample, provided the holding time of the sample is not exceeded.

(5) The frequency of monitoring for asbestos shall be in accordance with paragraph (b) of this section: the frequency of monitoring for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium and thallium shall be in accordance with paragraph (c) of this section; the frequency of monitoring for nitrate shall be in accordance with paragraph (d) of this section; and the frequency of monitoring for nitrite shall be in accordance with paragraph (e) of this section.

(b) The frequency of monitoring conducted to determine compliance with the maximum contaminant level for asbestos specified in § 141.62(b) shall be conducted as follows:

(1) Each community and non-transient, non-community water system is required to monitor for asbestos during the first three-year compliance period of each nine-year compliance cycle beginning in the compliance period starting January 1, 1993.

(2) If the system believes it is not vulnerable to either asbestos contamination in its source water or due to corrosion of asbestos-cement pipe, or both, it may apply to the State for a waiver of the monitoring requirement in paragraph (b)(1) of this section. If the State grants the waiver, the system is not required to monitor.

(3) The State may grant a waiver based on a consideration of the following factors:

(i) Potential asbestos contamination of the water source, and

(ii) The use of asbestos-cement pipe for finished water distribution and the corrosive nature of the water.

(4) A waiver remains in effect until the completion of the three-year compliance period. Systems not receiving a waiver must monitor in accordance with the provisions of paragraph (b)(1) of this section.

(5) A system vulnerable to asbestos contamination due solely to corrosion of asbestos-cement pipe shall take one sample at a tap served by asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

(6) A system vulnerable to asbestos contamination due solely to source water shall monitor in accordance with the provision of paragraph (a) of this section.

(7) A system vulnerable to asbestos contamination due both to its source water supply and corrosion of asbestos-cement pipe shall take one sample at a tap served by asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur.

(8) A system which exceeds the maximum contaminant levels as determined in § 141.23(i) of this section shall monitor quarterly beginning in the next quarter after the violation occurred.

(9) The State may decrease the quarterly monitoring requirement to the frequency specified in paragraph (b)(1) of this section provided the State has determined that the system is reliably and consistently below the maximum contaminant level. In no case can a State make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface (or combined surface/ground) water system takes a minimum of four quarterly samples.

(10) If monitoring data collected after January 1, 1990 are generally consistent with the requirements of § 141.23(b), then the State may allow systems to use that data to satisfy the monitoring requirement for the initial compliance period beginning January 1, 1993.

(c) The frequency of monitoring conducted to determine compliance with the maximum contaminant levels in § 141.62 for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium and thallium shall be as follows:

(1) Groundwater systems shall take one sample at each sampling point during each compliance period. Surface water systems (or combined surface/ground) shall take one sample annually at each sampling point.

(2) The system may apply to the State for a waiver from the monitoring frequencies specified in paragraph (c)(1) of this section. States may grant a public water system a waiver for monitoring of cyanide, provided that the State determines that the system is not vulnerable due to lack of any industrial source of cyanide.

(3) A condition of the waiver shall require that a system shall take a minimum of one sample while the waiver is effective. The term during which the waiver is effective shall not exceed one compliance cycle (i.e., nine years).

(4) The State may grant a waiver provided surface water systems have monitored annually for at least three years and groundwater systems have conducted a minimum of three rounds of monitoring. (At least one sample shall have been taken since January 1, 1990). Both surface and groundwater systems shall demonstrate that all previous analytical results were less than the maximum contaminant level. Systems that use a new water source are not eligible for a waiver until three rounds of monitoring from the new source have been completed.

(5) In determining the appropriate reduced monitoring frequency, the State shall consider:

(i) Reported concentrations from all previous monitoring;

(ii) The degree of variation in reported concentrations; and

(iii) Other factors which may affect contaminant concentrations such as changes in groundwater pumping rates, changes in the system's configuration, changes in the system's operating procedures, or changes in stream flows or characteristics.

(6) A decision by the State to grant a waiver shall be made in writing and shall set forth the basis for the determination. The determination may be initiated by the State or upon an application by the public water system. The public water system shall specify the basis for its request. The State shall review and, where appropriate, revise its determination of the appropriate monitoring frequency when the system submits new monitoring data or when other data relevant to the system's appropriate monitoring frequency become available.

(7) Systems which exceed the maximum contaminant levels as calculated in § 141.23(i) of this section shall monitor quarterly beginning in the next quarter after the violation occurred.

(8) The State may decrease the quarterly monitoring requirement to the frequencies specified in paragraphs (c)(1) and (c)(2) of this section provided it has determined that the system is reliably and consistently below the maximum contaminant level. In no case can a State make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface water system takes a minimum of four quarterly samples.

(9) All new systems or systems that use a new source of water that begin operation after January 22, 2004 must demonstrate compliance with the MCL within a period of time specified by the State. The system must also comply with the initial sampling frequencies specified by the State to ensure a system can demonstrate compliance with the MCL. Routine and increased monitoring frequencies shall be conducted in accordance with the requirements in this section.

(d) All public water systems (community; non-transient, non-community; and transient, non-community systems) shall monitor to determine compliance with the maximum contaminant level for nitrate in § 141.62.

(1) Community and non-transient, non-community water systems served by groundwater systems shall monitor annually beginning January 1, 1993; systems served by surface water shall monitor quarterly beginning January 1, 1993.

(2) For community and non-transient, non-community water systems, the repeat monitoring frequency for groundwater systems shall be quarterly for at least one year following any one sample in which the concentration is ≥50 percent of the MCL. The State may allow a groundwater system to reduce the sampling frequency to annually after four consecutive quarterly samples are reliably and consistently less than the MCL.

(3) For community and non-transient, non-community water systems, the State may allow a surface water system to reduce the sampling frequency to annually if all analytical results from four consecutive quarters are <50 percent of the MCL. A surface water system shall return to quarterly monitoring if any one sample is ≥50 percent of the MCL.

(4) Each transient non-community water system shall monitor annually beginning January 1, 1993.

(5) After the initial round of quarterly sampling is completed, each community and non-transient non-community system which is monitoring annually shall take subsequent samples during the quarter(s) which previously resulted in the highest analytical result.

(e) All public water systems (community; non-transient, non-community; and transient, non-community systems) shall monitor to determine compliance with the maximum contaminant level for nitrite in § 141.62(b).

(1) All public water systems shall take one sample at each sampling point in the compliance period beginning January 1, 1993 and ending December 31, 1995.

(2) After the initial sample, systems where an analytical result for nitrite is <50 percent of the MCL shall monitor at the frequency specified by the State.

(3) For community, non-transient, non-community, and transient non-community water systems, the repeat monitoring frequency for any water system shall be quarterly for at least one year following any one sample in which the concentration is ≥50 percent of the MCL. The State may allow a system to reduce the sampling frequency to annually after determining the system is reliably and consistently less than the MCL.

(4) Systems which are monitoring annually shall take each subsequent sample during the quarter(s) which previously resulted in the highest analytical result.

(f) Confirmation samples:

(1) Where the results of sampling for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium or thallium indicate an exceedance of the maximum contaminant level, the State may require that one additional sample be collected as soon as possible after the initial sample was taken (but not to exceed two weeks) at the same sampling point.

(2) Where nitrate or nitrite sampling results indicate an exceedance of the maximum contaminant level, the system shall take a confirmation sample within 24 hours of the system's receipt of notification of the analytical results of the first sample. Systems unable to comply with the 24-hour sampling requirement must immediately notify persons served by the public water system in accordance with § 141.202 and meet other Tier 1 public notification requirements under subpart Q of this part. Systems exercising this option must take and analyze a confirmation sample within two weeks of notification of the analytical results of the first sample.

(3) If a State-required confirmation sample is taken for any contaminant, then the results of the initial and confirmation sample shall be averaged. The resulting average shall be used to determine the system's compliance in accordance with paragraph (i) of this section. States have the discretion to delete results of obvious sampling errors.

(g) The State may require more frequent monitoring than specified in paragraphs (b), (c), (d) and (e) of this section or may require confirmation samples for positive and negative results at its discretion.

(h) Systems may apply to the State to conduct more frequent monitoring than the minimum monitoring frequencies specified in this section.

(i) Compliance with § 141.11 or § 141.62(b) (as appropriate) shall be determined based on the analytical result(s) obtained at each sampling point.

(1) For systems which are conducting monitoring at a frequency greater than annual, compliance with the maximum contaminant levels for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium or thallium is determined by a running annual average at any sampling point. If the average at any sampling point is greater than the MCL, then the system is out of compliance. If any one sample would cause the annual average to be exceeded, then the system is out of compliance immediately. Any sample below the method detection limit shall be calculated at zero for the purpose of determining the annual average. If a system fails to collect the required number of samples, compliance (average concentration) will be based on the total number of samples collected.

(2) For systems which are monitoring annually, or less frequently, the system is out of compliance with the maximum contaminant levels for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium or thallium if the level of a contaminant is greater than the MCL. If confirmation samples are required by the State, the determination of compliance will be based on the annual average of the initial MCL exceedance and any State-required confirmation samples. If a system fails to collect the required number of samples, compliance (average concentration) will be based on the total number of samples collected.

(3) Compliance with the maximum contaminant levels for nitrate and nitrate is determined based on one sample if the levels of these contaminants are below the MCLs. If the levels of nitrate and/or nitrite exceed the MCLs in the initial sample, a confirmation sample is required in accordance with paragraph (f)(2) of this section, and compliance shall be determined based on the average of the initial and confirmation samples.

(4) Arsenic sampling results will be reported to the nearest 0.001 mg/L.

(j) Each public water system shall monitor at the time designated by the State during each compliance period.

(k) Inorganic analysis:

(1) Analysis for the following contaminants shall be conducted in accordance with the methods in the following table, or the alternative methods listed in appendix A to subpart C of this part, or their equivalent as determined by EPA. Criteria for analyzing arsenic, barium, beryllium, cadmium, calcium, chromium, copper, lead, nickel, selenium, sodium, and thallium with digestion or directly without digestion, and other analytical test procedures are contained in Technical Notes on Drinking Water Methods, EPA-600/R-94-173, October 1994. This document is available from the National Service Center for Environmental Publications (NSCEP), P.O. Box 42419, Cincinnati, OH 45242-0419 or http://www.epa.gov/nscep/.

Contaminant Methodology13 EPA ASTM3 SM4 (18th, 19th ed.) SM4 (20th ed.) SM Online22 Other
1. Alkalinity Titrimetric D1067-92, 02 B 2320 B 2320 B 2320 B-97
Electrometric titration I-1030-855
2. Antimony Inductively Coupled Plasma (ICP) - Mass Spectrometry 200.82
Hydride-Atomic Absorption D3697-92, 02
Atomic Absorption; Platform 200.92
Atomic Absorption; Furnace 3113 B 3113 B-99
3. Arsenic14 ICP-Mass Spectrometry 200.82
Atomic Absorption; Platform 200.92
Atomic Absorption; Furnace D2972-97, 03 C 3113 B 3113 B-99
Hydride Atomic Absorption D1972-97, 03 B 3114 B 3114 B-97
4. Asbestos Transmission Electron Microscopy 100.19
Transmission Electron Microscopy 100.210
5. Barium Inductively Coupled Plasma 200.72 3120 B 3120 B 3120 B-99
ICP-Mass Spectrometry 200.82
Atomic Absorption; Direct 3111D 3111 D-99
Atomic Absorption; Furnace 3113 B 3113 B-99
6. Beryllium Inductively Coupled Plasma 200.72 3120 B 3120 B 3120 B-99
ICP-Mass Spectrometry 200.82
Atomic Absorption; Platform 200.92
Atomic Absorption; Furnace D3645-97, 03 B 3113 B 3113 B-99
7. Cadmium Inductively Coupled Plasma 200.72
ICP-Mass Spectrometry 200.82
Atomic Absorption; Platform 200.92
Atomic Absorption; Furnace 3113 B 3113 B-99
8. Calcium EDTA titrimetric D511-93, 03 A 3500-Ca D 3500-Ca B 3500-Ca B-97
Atomic Absorption; Direct Aspiration D511-93, 03 B 3111 B 3111 B-99
Inductively Coupled Plasma 200.72 3120 B 3120 B 3120 B-99
Ion Chromatography D6919-03
9. Chromium Inductively Coupled Plasma 200.72 3120 B 3120 B 3120 B-99
ICP-Mass Spectrometry 200.82
Atomic Absorption; Platform 200.92
Atomic Absorption; Furnace 3113 B 3113 B-99
10. Copper Atomic Absorption; Furnace D1688-95, 02 C 3113 B 3113 B-99
Atomic Absorption; Direct Aspiration D1688-95, 02 A 3111 B 3111 B-99
Inductively Coupled Plasma 200.72 3120 B 3120 B 3120 B-99
ICP-Mass spectrometry 200.82
Atomic Absorption; Platform 200.92
11. Conductivity Conductance D1125-95 (Reapproved 1999) A 2510 B 2510 B 2510 B-97
12. Cyanide Manual Distillation followed by D2036-98 A 4500-CN C 4500-CN C
Spectrophotometric, Amenable D2036-98 B 4500-CN G 4500-CN G 4500-CN G-99
Spectro-photometric Manual D2036-98 A 4500-CN E 4500-CN E 4500-CN E-99 I-3300-855
Spectro-photometric Semi-automated 335.46
Selective Electrode 4500-CN F 4500-CN F 4500-CN F-99
UV, Distillation, Spectrophotometric Kelada-0117
Micro Distillation, Flow Injection, Spectrophotometric QuikChem 10-204-00-1-X18
Ligand Exchange and Amperometry21 D6888-04 OIA-1677, DW20
13. Fluoride Ion Chromatography 300.06, 300.119 D4327-97, 03 4110 B 4110 B 4110 B-00
Manual Distill.; Color. SPADNS 4500-F B, D 4500-F B, D 4500-F B, D-97
Manual Electrode D1179-93, 99 B 4500-F C 4500-F C 4500-F C-97
Automated Electrode 380-75WE11
Automated Alizarin 4500-F E 4500-F E 4500-F E-97 129-71W11
Capillary Ion Electrophoresis D6508, Rev. 223
14. Lead Atomic Absorption; Furnace D3559-96, 03 D 3113 B 3113 B-99
ICP-Mass spectrometry 200.82
Atomic Absorption; Platform 200.92
Differential Pulse Anodic Stripping Voltametry Method 100116
15. Magnesium Atomic Absorption D511-93, 03 B 3111 B 3111 B-99
ICP 200.72 3120 B 3120 B 3120 B-99
Complexation Titrimetric Methods D511-93, 03 A 3500-Mg E 3500-Mg B 3500-Mg B-97
Ion Chromatography D6919-03
16. Mercury Manual, Cold Vapor 245.12 D3223-97, 02 3112 B 3112 B-99
Automated, Cold Vapor 245.21
ICP-Mass Spectrometry 200.82
17. Nickel Inductively Coupled Plasma 200.72 3120 B 3120 B 3120 B-99
ICP-Mass Spectrometry 200.82
Atomic Absorption; Platform 200.92
Atomic Absorption; Direct 3111 B 3111 B-99
Atomic Absorption; Furnace 3113 B 3113 B-99
18. Nitrate Ion Chromatography 300.06, 300.119 D4327-97, 03 4110 B 4110 B 4110 B-00 B-10118
Automated Cadmium Reduction 353.26 D3867-90 A 4500-NO3 F 4500-NO3 F 4500-NO3 F-00
Ion Selective Electrode 4500-NO3 D 4500-NO3 D 4500-NO3 D-00 6017
Manual Cadmium Reduction D3867-90 B 4500-NO3 E 4500-NO3 E 4500-NO3 E-00
Capillary Ion Electrophoresis D6508-00.
19. Nitrite Ion Chromatography 300.06, 300.119 D4327-97, 03 4110 B 4110 B 4110 B-00 B-10118
Automated Cadmium Reduction 353.26 D3867-90 A 4500-NO3 F 4500-NO3 F 4500-NO3 F-00
Manual Cadmium Reduction D3867-90 B 4500-NO3 E 4500-NO3 E 4500-NO3 E-00
Spectrophotometric 4500-NO2 B 4500-NO2 B 4500-NO2 B-00
Capillary Ion Electrophoresis D6508-00
20. Ortho-phosphate Colorimetric, Automated, Ascorbic Acid 365.16 4500-P F 4500-P F
Colorimetric, ascorbic acid, single reagent D515-88 A 4500-P E 4500-P E
Colorimetric Phosphomolybdate; Automated-segmented flow; Automated Discrete I-1601-855
I-2601-905
I-2598-855
Ion Chromatography 300.06, 300.119 D4327-97, 03 4110 B 4110 B 4110 B-00
Capillary Ion Electrophoresis D6508-00
21. pH Electrometric 150.1, 150.21 D1293-95, 99 4500-H+ B 4500-H+ B 4500-H+ B-00
22. Selenium Hydride-Atomic Absorption D3859-98, 03 A 3114 B 3114 B-97
ICP-Mass Spectrometry 200.82
Atomic Absorption; Platform 200.92
Atomic Absorption; Furnace D3859-98, 03 B 3113 B 3113 B-99
23. Silica Colorimetric, Molybdate Blue I-1700-855
Automated-segmented Flow I-2700-855
Colorimetric D859-94, 00
Molybdosilicate 4500-Si D 4500-SiO2 C 4500-SiO2 C-97
Heteropoly blue 4500-Si E 4500-SiO2 D 4500-SiO2 D-97
Automated for Molybdate-reactive Silica 4500-Si F 4500-SiO2 E 4500-SiO2 E-97
Inductively Coupled Plasma 200.72 3120 B 3120 B 3120 B-99
24. Sodium Inductively Coupled Plasma 200.72
Atomic Absorption; Direct Aspiration 3111 B 3111 B-99
Ion Chromatography D6919-03
25. Temperature Thermometric 2550 2550 2550-00
26. Thallium ICP-Mass Spectrometry 200.82
Atomic Absorption; Platform 200.92

(2) Sample collection for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, nitrate, nitrite, selenium, and thallium under this section shall be conducted using the sample preservation, container, and maximum holding time procedures specified in the table below:

Contaminant Preservative1 Container2 Time3
Antimony HNO3 P or G 6 months
Arsenic Conc HNO3 to pH <2 P or G 6 months
Asbestos 4 °C P or G 48 hours4
Barium HNO3 P or G 6 months
Beryllium HNO3 P or G 6 months
Cadmium HNO3 P or G 6 months
Chromium HNO3 P or G 6 months
Cyanide 4 °C, NaOH P or G 14 days
Fluoride None P or G 1 month
Mercury HNO3 P or G 28 days
Nickel HNO3 P or G 6 months
Nitrate 4 °C P or G 48 hours5
Nitrate-Nitrite6 H2SO4 P or G 28 days
Nitrite 4 °C P or G 48 hours
Selenium HNO3 P or G 6 months
Thallium HNO3 P or G 6 months

(3) Analysis under this section shall only be conducted by laboratories that have been certified by EPA or the State. Laboratories may conduct sample analysis under provisional certification until January 1, 1996. To receive certification to conduct analyses for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, nitrate, nitrite and selenium and thallium, the laboratory must:

(i) Analyze Performance Evaluation (PE) samples provided by EPA, the State or by a third party (with the approval of the State or EPA) at least once a year.

(ii) For each contaminant that has been included in the PE sample and for each method for which the laboratory desires certification achieve quantitative results on the analyses that are within the following acceptance limits:

Contaminant Acceptance limit
Antimony ±30 at ≥0.006 mg/1
Arsenic ±30 at ≥0.003 mg/L
Asbestos 2 standard deviations based on study statistics.
Barium ±15% at ≥0.15 mg/1
Beryllium ±15% at ≥0.001 mg/1
Cadmium ±20% at ≥0.002 mg/1
Chromium ±15% at ≥0.01 mg/1
Cyanide ±25% at ≥0.1 mg/1
Fluoride ±10% at ≥1 to 10 mg/1
Mercury ±30% at ≥0.0005 mg/1
Nickel ±15% at ≥0.01 mg/1
Nitrate ±10% at ≥0.4 mg/1
Nitrite ±15% at ≥0.4 mg/1
Selenium ±20% at ≥0.01 mg/1
Thallium ±30% at ≥0.002 mg/1

(l) Analyses for the purpose of determining compliance with § 141.11 shall be conducted using the requirements specified in paragraphs (l) through (q) of this section.

(1) Analyses for all community water systems utilizing surface water sources shall be completed by June 24, 1978. These analyses shall be repeated at yearly intervals.

(2) Analyses for all community water systems utilizing only ground water sources shall be completed by June 24, 1979. These analyses shall be repeated at three-year intervals.

(3) For non-community water systems, whether supplied by surface or ground sources, analyses for nitrate shall be completed by December 24, 1980. These analyses shall be repeated at intervals determined by the State.

(4) The State has the authority to determine compliance or initiate enforcement action based upon analytical results and other information compiled by their sanctioned representatives and agencies.

(m) If the result of an analysis made under paragraph (l) of this section indicates that the level of any contaminant listed in § 141.11 exceeds the maximum contaminant level, the supplier of the water shall report to the State within 7 days and initiate three additional analyses at the same sampling point within one month.

(n) When the average of four analyses made pursuant to paragraph (m) of this section, rounded to the same number of significant figures as the maximum contaminant level for the substance in question, exceeds the maximum contaminant level, the supplier of water shall notify the State pursuant to § 141.31 and give notice to the public pursuant to subpart Q. Monitoring after public notification shall be at a frequency designated by the State and shall continue until the maximum contaminant level has not been exceeded in two successive samples or until a monitoring schedule as a condition to a variance, exemption or enforcement action shall become effective.

(o) The provisions of paragraphs (m) and (n) of this section notwithstanding, compliance with the maximum contaminant level for nitrate shall be determined on the basis of the mean of two analyses. When a level exceeding the maximum contaminant level for nitrate is found, a second analysis shall be initiated within 24 hours, and if the mean of the two analyses exceeds the maximum contaminant level, the supplier of water shall report his findings to the State pursuant to § 141.31 and shall notify the public pursuant to subpart Q.

(p) For the initial analyses required by paragraph (l) (1), (2) or (3) of this section, data for surface waters acquired within one year prior to the effective date and data for ground waters acquired within 3 years prior to the effective date of this part may be substituted at the discretion of the State.

(q) [Reserved]

[56 FR 3579, Jan. 30, 1991]

§ 141.24 Organic chemicals, sampling and analytical requirements.

(a-d) [Reserved]

(e) Analyses for the contaminants in this section shall be conducted using the methods listed in the following table, or the alternative methods listed in appendix A to subpart C of this part, or their equivalent as determined by EPA.

(1) The following documents are incorporated by reference. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be inspected at EPA's Drinking Water Docket, 1301 Constitution Avenue, NW., EPA West, Room 3334, Washington, DC 20460 (Telephone: 202-566-2426); or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. Method 508A and 515.1 are in Methods for the Determination of Organic Compounds in Drinking Water, EPA/600/4-88-039, December 1988, Revised, July 1991. Methods 547, 550 and 550.1 are in Methods for the Determination of Organic Compounds in Drinking Water - Supplement I, EPA/600-4-90-020, July 1990. Methods 548.1, 549.1, 552.1 and 555 are in Methods for the Determination of Organic Compounds in Drinking Water - Supplement II, EPA/600/R-92-129, August 1992. Methods 502.2, 504.1, 505, 506, 507, 508, 508.1, 515.2, 524.2 525.2, 531.1, 551.1 and 552.2 are in Methods for the Determination of Organic Compounds in Drinking Water--Supplement III, EPA/600/R-95-131, August 1995. Method 1613 is titled “Tetra-through Octa-Chlorinated Dioxins and Furans by Isotope-Dilution HRGC/HRMS,” EPA/821-B-94-005, October 1994. These documents are available from the National Technical Information Service, NTIS PB91-231480, PB91-146027, PB92-207703, PB95-261616 and PB95-104774, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161. The toll free number is: 800-553-6847. Method 6651 shall be followed in accordance with Standard Methods for the Examination of Water and Wastewater, 18th edition (1992), 19th edition (1995), or 20th edition (1998), American Public Health Association (APHA); any of these three editions may be used. Method 6610 shall be followed in accordance with Standard Methods for the Examination of Water and Wastewater, (18th Edition Supplement) (1994), or with the 19th edition (1995) or 20th edition (1998) of Standard Methods for the Examination of Water and Wastewater; any of these publications may be used. The APHA documents are available from APHA, 1015 Fifteenth Street NW., Washington, DC 20005. Other required analytical test procedures germane to the conduct of these analyses are contained in Technical Notes on Drinking Water Methods, EPA/600/R-94-173, October 1994, NTIS PB95-104766. EPA Methods 515.3 and 549.2 are available from U.S. Environmental Protection Agency, National Exposure Research Laboratory (NERL)-Cincinnati, 26 West Martin Luther King Drive, Cincinnati, OH 45268. ASTM Method D 5317-93, 98 (Reapproved 2003) is available in the Annual Book of ASTM Standards, (1999), Vol. 11.02, ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, any edition containing the cited version of the method may be used. EPA Method 515.4, “Determination of Chlorinated Acids in Drinking Water by Liquid-Liquid Microextraction, Derivatization and Fast Gas Chromatography with Electron Capture Detection,” Revision 1.0, April 2000, EPA/815/B-00/001 and EPA Method 552.3, “Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-Liquid Microextraction, Derivatization, and Gas Chromatography with Electron Capture Detection,” Revision 1.0, July 2003, EPA 815-B-03-002, can be accessed and downloaded directly online at http://www.epa.gov/safewater/methods/sourcalt.html. Syngenta Method AG-625, “Atrazine in Drinking Water by Immunoassay,” February 2001, is available from Syngenta Crop Protection, Inc., 410 Swing Road, P.O. Box 18300, Greensboro, NC 27419. Telephone: 336-632-6000. Method 531.2 “Measurement of N-methylcarbamoyloximes and N-methylcarbamates in Water by Direct Aqueous Injection HPLC with Postcolumn Derivatization,” Revision 1.0, September 2001, EPA 815-B-01-002, can be accessed and downloaded directly online at http://www.epa.gov/safewater/methods/sourcalt.html.

Contaminant EPA method Standard methods ASTM Other
1. Benzene 502.2, 524.2
2. Carbon tetrachloride 502.2, 524.2, 551.1
3. Chlorobenzene 502.2, 524.2
4. 1,2-Dichlorobenzene 502.2, 524.2
5. 1,4-Dichlorobenzene 502.2, 524.2
6. 1,2-Dichloroethane 502.2, 524.2
7. cis-Dichloroethylene 502.2, 524.2
8. trans-Dichloroethylene 502.2, 524.2
9. Dichloromethane 502.2, 524.2
10. 1,2-Dichloropropane 502.2, 524.2
11. Ethylbenzene 502.2, 524.2
12. Styrene 502.2, 524.2
13. Tetrachloroethylene 502.2, 524.2, 551.1
14. 1,1,1-Trichloroethane 502.2, 524.2, 551.1
15. Trichloroethylene 502.2, 524.2, 551.1
16. Toluene 502.2, 524.2
17. 1,2,4-Trichlorobenzene 502.2, 524.2
18. 1,1-Dichloroethylene 502.2, 524.2
19. 1,1,2-Trichloroethane 502.2, 524.2, 551.1
20. Vinyl chloride 502.2, 524.2
21. Xylenes (total) 502.2, 524.2
22. 2,3,7,8-TCDD (dioxin) 1613
23. 2,4-D4 (as acids, salts, and esters) 515.2, 555, 515.1, 515.3, 515.4 D5317-93, 98 (Reapproved 2003)
24. 2,4,5-TP4 (Silvex) 515.2, 555, 515.1, 515.3, 515.4 D5317-93, 98 (Reapproved 2003)
25. Alachlor2 507, 525.2, 508.1, 505, 551.1
26. Atrazine2 507, 525.2, 508.1, 505, 551.1 Syngenta5 AG-625
27. Benzo(a)pyrene 525.2, 550, 550.1
28. Carbofuran 531.1, 531.2 6610
29. Chlordane 508, 525.2, 508.1, 505
30. Dalapon 552.1 515.1, 552.2, 515.3, 515.4, 552.3
31. Di(2-ethylhexyl)adipate 506, 525.2
32. Di(2-ethylhexyl)phthalate 506, 525.2
33. Dibromochloropropane (DBCP) 504.1, 551.1
34. Dinoseb4 515.2, 555, 515.1, 515.3, 515.4
35. Diquat 549.2
36. Endothall 548.1
37. Endrin 508, 525.2, 508.1, 505, 551.1
38. Ethylene dibromide (EDB) 504.1, 551.1
39. Glyphosate 547 6651
40. Heptachlor 508, 525.2, 508.1, 505, 551.1
41. Heptachlor Epoxide 508, 525.2, 508.1, 505, 551.1
42. Hexachlorobenzene 508, 525.2, 508.1, 505, 551.1
43. Hexachlorocyclopentadiene 508, 525.2, 508.1, 505, 551.1
44. Lindane 508, 525.2, 508.1, 505, 551.1
45. Methoxychlor 508, 525.2, 508.1, 505, 551.1
46. Oxamyl 531.1, 531.2 6610
47. PCBs3 (as decachlorobiphenyl) 508A
48. PCBs3 (as Aroclors) 508.1, 508, 525.2, 505
49. Pentachlorophenol 515.2, 525.2, 555, 515.1, 515.3, 515.4 D5317-93, 98 (Reapproved 2003)
50. Picloram4 515.2, 555, 515.1, 515.3, 515.4 D5317-93, 98 (Reapproved 2003)
51. Simazine2 507, 525.2, 508.1, 505, 551.1
52. Toxaphene 508, 508.1, 525.2, 505
53. Total Trihalomethanes 502.2, 524.2, 551.1

(2) [Reserved]

(f) Beginning with the initial compliance period, analysis of the contaminants listed in § 141.61(a) (1) through (21) for the purpose of determining compliance with the maximum contaminant level shall be conducted as follows:

(1) Groundwater systems shall take a minimum of one sample at every entry point to the distribution system which is representative of each well after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source, treatment plant, or within the distribution system.

(2) Surface water systems (or combined surface/ground) shall take a minimum of one sample at points in the distribution system that are representative of each source or at each entry point to the distribution system after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source, treatment plant, or within the distribution system.

(3) If the system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water representative of all sources is being used).

(4) Each community and non-transient non-community water system shall take four consecutive quarterly samples for each contaminant listed in § 141.61(a) (2) through (21) during each compliance period, beginning in the initial compliance period.

(5) If the initial monitoring for contaminants listed in § 141.61(a) (1) through (8) and the monitoring for the contaminants listed in § 141.61(a) (9) through (21) as allowed in paragraph (f)(18) has been completed by December 31, 1992, and the system did not detect any contaminant listed in § 141.61(a) (1) through (21), then each ground and surface water system shall take one sample annually beginning with the initial compliance period.

(6) After a minimum of three years of annual sampling, the State may allow groundwater systems with no previous detection of any contaiminant listed in § 141.61(a) to take one sample during each compliance period.

(7) Each community and non-transient non-community ground water system which does not detect a contaminant listed in § 141.61(a) (1) through (21) may apply to the State for a waiver from the requirements of paragraphs (f)(5) and (f)(6) of this section after completing the initial monitoring. (For purposes of this section, detection is defined as ≥0.0005 mg/l.) A waiver shall be effective for no more than six years (two compliance periods). States may also issue waivers to small systems for the initial round of monitoring for 1,2,4-trichlorobenzene.

(8) A State may grant a waiver after evaluating the following factor(s):

(i) Knowledge of previous use (including transport, storage, or disposal) of the contaminant within the watershed or zone of influence of the system. If a determination by the State reveals no previous use of the contaminant within the watershed or zone of influence, a waiver may be granted.

(ii) If previous use of the contaminant is unknown or it has been used previously, then the following factors shall be used to determine whether a waiver is granted.

(A) Previous analytical results.

(B) The proximity of the system to a potential point or non-point source of contamination. Point sources include spills and leaks of chemicals at or near a water treatment facility or at manufacturing, distribution, or storage facilities, or from hazardous and municipal waste landfills and other waste handling or treatment facilities.

(C) The environmental persistence and transport of the contaminants.

(D) The number of persons served by the public water system and the proximity of a smaller system to a larger system.

(E) How well the water source is protected against contamination, such as whether it is a surface or groundwater system. Groundwater systems must consider factors such as depth of the well, the type of soil, and wellhead protection. Surface water systems must consider watershed protection.

(9) As a condition of the waiver a groundwater system must take one sample at each sampling point during the time the waiver is effective (i.e., one sample during two compliance periods or six years) and update its vulnerability assessment considering the factors listed in paragraph (f)(8) of this section. Based on this vulnerability assessment the State must reconfirm that the system is non-vulnerable. If the State does not make this reconfirmation within three years of the initial determination, then the waiver is invalidated and the system is required to sample annually as specified in paragraph (5) of this section.

(10) Each community and non-transient non-community surface water system which does not detect a contaminant listed in § 141.61(a) (1) through (21) may apply to the State for a waiver from the requirements of (f)(5) of this section after completing the initial monitoring. Composite samples from a maximum of five sampling points are allowed, provided that the detection limit of the method used for analysis is less than one-fifth of the MCL. Systems meeting this criterion must be determined by the State to be non-vulnerable based on a vulnerability assessment during each compliance period. Each system receiving a waiver shall sample at the frequency specified by the State (if any).

(11) If a contaminant listed in § 141.61(a) (2) through (21) is detected at a level exceeding 0.0005 mg/l in any sample, then:

(i) The system must monitor quarterly at each sampling point which resulted in a detection.

(ii) The State may decrease the quarterly monitoring requirement speci fied in paragraph (f)(11)(i) of this section provided it has determined that the system is reliably and consistently below the maximum contaminant level. In no case shall the State make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface water system takes a minimum of four quarterly samples.

(iii) If the State determines that the system is reliably and consistently below the MCL, the State may allow the system to monitor annually. Systems which monitor annually must monitor during the quarter(s) which previously yielded the highest analytical result.

(iv) Systems which have three consecutive annual samples with no detection of a contaminant may apply to the State for a waiver as specified in paragraph (f)(7) of this section.

(v) Groundwater systems which have detected one or more of the following two-carbon organic compounds: trichloroethylene, tetrachloroethylene, 1,2-dichloroethane, 1,1,1-trichloroethane, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, or 1,1-dichloroethylene shall monitor quarterly for vinyl chloride. A vinyl chloride sample shall be taken at each sampling point at which one or more of the two-carbon organic compounds was detected. If the results of the first analysis do not detect vinyl chloride, the State may reduce the quarterly monitoring frequency of vinyl chloride monitoring to one sample during each compliance period. Surface water systems are required to monitor for vinyl chloride as specified by the State.

(12) Systems which violate the requirements of § 141.61(a) (1) through (21), as determined by paragraph (f)(15) of this section, must monitor quarterly. After a minimum of four consecutive quarterly samples which show the system is in compliance as specified in paragraph (f)(15) of this section the system and the State determines that the system is reliably and consistently below the maximum contaminant level, the system may monitor at the frequency and times specified in paragraph (f)(11)(iii) of this section.

(13) The State may require a confirmation sample for positive or negative results. If a confirmation sample is required by the State, the result must be averaged with the first sampling result and the average is used for the compliance determination as specified by paragraph (f)(15). States have discretion to delete results of obvious sampling errors from this calculation.

(14) The State may reduce the total number of samples a system must analyze by allowing the use of compositing. Composite samples from a maximum of five sampling points are allowed, provided that the detection limit of the method used for analysis is less than one-fifth of the MCL. Compositing of samples must be done in the laboratory and analyzed within 14 days of sample collection.

(i) If the concentration in the composite sample is greater than or equal to 0.0005 mg/l for any contaminant listed in § 141.61(a), then a follow-up sample must be taken within 14 days at each sampling point included in the composite, and be analyzed for that contaminant.

(ii) If duplicates of the original sample taken from each sampling point used in the composite sample are available, the system may use these instead of resampling. The duplicates must be analyzed and the results reported to the State within 14 days after completing analysis of the composite sample, provided the holding time of the sample is not exceeded.

(iii) If the population served by the system is >3,300 persons, then compositing may only be permitted by the State at sampling points within a single system. In systems serving ≤3,300 persons, the State may permit compositing among different systems provided the 5-sample limit is maintained.

(iv) Compositing samples prior to GC analysis.

(A) Add 5 ml or equal larger amounts of each sample (up to 5 samples are allowed) to a 25 ml glass syringe. Special precautions must be made to maintain zero headspace in the syringe.

(B) The samples must be cooled at 4 °C during this step to minimize volatilization losses.

(C) Mix well and draw out a 5-ml aliquot for analysis.

(D) Follow sample introduction, purging, and desorption steps described in the method.

(E) If less than five samples are used for compositing, a proportionately small syringe may be used.

(v) Compositing samples prior to GC/MS analysis.

(A) Inject 5-ml or equal larger amounts of each aqueous sample (up to 5 samples are allowed) into a 25-ml purging device using the sample introduction technique described in the method.

(B) The total volume of the sample in the purging device must be 25 ml.

(C) Purge and desorb as described in the method.

(15) Compliance with § 141.61(a) (1) through (21) shall be determined based on the analytical results obtained at each sampling point. If one sampling point is in violation of an MCL, the system is in violation of the MCL.

(i) For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point.

(ii) Systems monitoring annually or less frequently whose sample result exceeds the MCL must begin quarterly sampling. The system will not be considered in violation of the MCL until it has completed one year of quarterly sampling.

(iii) If any sample result will cause the running annual average to exceed the MCL at any sampling point, the system is out of compliance with the MCL immediately.

(iv) If a system fails to collect the required number of samples, compliance will be based on the total number of samples collected.

(v) If a sample result is less than the detection limit, zero will be used to calculate the annual average.

(16) [Reserved]

(17) Analysis under this section shall only be conducted by laboratories that are certified by EPA or the State according to the following conditions (laboratories may conduct sample analysis under provisional certification until January 1, 1996):

(i) To receive certification to conduct analyses for the contaminants in § 141.61(a) (2) through (21) the laboratory must:

(A) Analyze Performance Evaluation (PE) samples provided by EPA, the State, or by a third party (with the approval of the State or EPA) at least once a year by each method for which the laboratory desires certification.

(B) Achieve the quantitative acceptance limits under paragraphs (f)(17)(i)(C) and (D) of this section for at least 80 percent of the regulated organic contaminants included in the PE sample.

(C) Achieve quantitative results on the analyses performed under paragraph (f)(17)(i)(A) of this section that are within ±20% of the actual amount of the substances in the Performance Evaluation sample when the actual amount is greater than or equal to 0.010 mg/l.

(D) Achieve quantitative results on the analyses performed under paragraph (f)(17)(i)(A) of this section that are within ±40 percent of the actual amount of the substances in the Performance Evaluation sample when the actual amount is less than 0.010 mg/l.

(E) Achieve a method detection limit of 0.0005 mg/l, according to the procedures in appendix B of part 136.

(ii) To receive certification to conduct analyses for vinyl chloride, the laboratory must:

(A) Analyze Performance Evaluation (PE) samples provided by EPA, the State, or by a third party (with the approval of the State or EPA) at least once a year by each method for which the laboratory desires certification.

(B) Achieve quantitative results on the analyses performed under paragraph (f)(17)(ii)(A) of this section that are within ±40 percent of the actual amount of vinyl chloride in the Performance Evaluation sample.

(C) Achieve a method detection limit of 0.0005 mg/l, according to the procedures in appendix B of part 136.

(D) Obtain certification for the contaminants listed in § 141.61(a)(2) through (21).

(18) States may allow the use of monitoring data collected after January 1, 1988, required under section 1445 of the Act for purposes of initial monitoring compliance. If the data are generally consistent with the other requirements of this section, the State may use these data (i.e., a single sample rather than four quarterly samples) to satisfy the initial monitoring requirement of paragraph (f)(4) of this section. Systems which use grandfathered samples and did not detect any contaminant listed § 141.61(a)(2) through (21) shall begin monitoring annually in accordance with paragraph (f)(5) of this section beginning with the initial compliance period.

(19) States may increase required monitoring where necessary to detect variations within the system.

(20) Each certified laboratory must determine the method detection limit (MDL), as defined in appendix B to part 136, at which it is capable of detecting VOCs. The acceptable MDL is 0.0005 mg/l. This concentration is the detection concentration for purposes of this section.

(21) Each public water system shall monitor at the time designated by the State within each compliance period.

(22) All new systems or systems that use a new source of water that begin operation after January 22, 2004 must demonstrate compliance with the MCL within a period of time specified by the State. The system must also comply with the initial sampling frequencies specified by the State to ensure a system can demonstrate compliance with the MCL. Routine and increased monitoring frequencies shall be conducted in accordance with the requirements in this section.

(g) [Reserved]

(h) Analysis of the contaminants listed in § 141.61(c) for the purposes of determining compliance with the maximum contaminant level shall be conducted as follows, with the exception that no monitoring is required for aldicarb, aldicarb sulfoxide or aldicarb sulfone:

(1) Groundwater systems shall take a minimum of one sample at every entry point to the distribution system which is representative of each well after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant.

(2) Surface water systems shall take a minimum of one sample at points in the distribution system that are representative of each source or at each entry point to the distribution system after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant.

Note:

For purposes of this paragraph, surface water systems include systems with a combination of surface and ground sources.

(3) If the system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water representative of all sources is being used).

(4) Monitoring frequency:

(i) Each community and non-transient non-community water system shall take four consecutive quarterly samples for each contaminant listed in § 141.61(c) during each compliance period beginning with the initial compliance period.

(ii) Systems serving more than 3,300 persons which do not detect a contaminant in the initial compliance period may reduce the sampling frequency to a minimum of two quarterly samples in one year during each repeat compliance period.

(iii) Systems serving less than or equal to 3,300 persons which do not detect a contaminant in the initial compliance period may reduce the sampling frequency to a minimum of one sample during each repeat compliance period.

(5) Each community and non-transient water system may apply to the State for a waiver from the requirement of paragraph (h)(4) of this section. A system must reapply for a waiver for each compliance period.

(6) A State may grant a waiver after evaluating the following factor(s): Knowledge of previous use (including transport, storage, or disposal) of the contaminant within the watershed or zone of influence of the system. If a determination by the State reveals no previous use of the contaminant within the watershed or zone of influence, a waiver may be granted. If previous use of the contaminant is unknown or it has been used previously, then the following factors shall be used to determine whether a waiver is granted.

(i) Previous analytical results.

(ii) The proximity of the system to a potential point or non-point source of contamination. Point sources include spills and leaks of chemicals at or near a water treatment facility or at manufacturing, distribution, or storage facilities, or from hazardous and municipal waste landfills and other waste handling or treatment facilities. Non-point sources include the use of pesticides to control insect and weed pests on agricultural areas, forest lands, home and gardens, and other land application uses.

(iii) The environmental persistence and transport of the pesticide or PCBs.

(iv) How well the water source is protected against contamination due to such factors as depth of the well and the type of soil and the integrity of the well casing.

(v) Elevated nitrate levels at the water supply source.

(vi) Use of PCBs in equipment used in the production, storage, or distribution of water (i.e., PCBs used in pumps, transformers, etc.).

(7) If an organic contaminant listed in § 141.61(c) is detected (as defined by paragraph (h)(18) of this section) in any sample, then:

(i) Each system must monitor quarterly at each sampling point which resulted in a detection.

(ii) The State may decrease the quarterly monitoring requirement specified in paragraph (h)(7)(i) of this section provided it has determined that the system is reliably and consistently below the maximum contaminant level. In no case shall the State make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface water system takes a minimum of four quarterly samples.

(iii) After the State determines the system is reliably and consistently below the maximum contaminant level the State may allow the system to monitor annually. Systems which monitor annually must monitor during the quarter that previously yielded the highest analytical result.

(iv) Systems which have 3 consecutive annual samples with no detection of a contaminant may apply to the State for a waiver as specified in paragraph (h)(6) of this section.

(v) If the monitoring results in detection of one or more of certain related contaminants (heptachlor and heptachlor epoxide), then subsequent monitoring shall analyze for all related contaminants.

(8) Systems which violate the requirements of § 141.61(c) as determined by paragraph (h)(11) of this section must monitor quarterly. After a minimum of four quarterly samples show the system is in compliance and the State determines the system is reliably and consistently below the MCL, as specified in paragraph (h)(11) of this section, the system shall monitor at the frequency specified in paragraph (h)(7)(iii) of this section.

(9) The State may require a confirmation sample for positive or negative results. If a confirmation sample is required by the State, the result must be averaged with the first sampling result and the average used for the compliance determination as specified by paragraph (h)(11) of this section. States have discretion to delete results of obvious sampling errors from this calculation.

(10) The State may reduce the total number of samples a system must analyze by allowing the use of compositing. Composite samples from a maximum of five sampling points are allowed, provided that the detection limit of the method used for analysis is less than one-fifth of the MCL. Compositing of samples must be done in the laboratory and analyzed within 14 days of sample collection.

(i) If the concentration in the composite sample detects one or more contaminants listed in § 141.61(c), then a follow-up sample must be taken within 14 days at each sampling point included in the composite, and be analyzed for that contaminant.

(ii) If duplicates of the original sample taken from each sampling point used in the composite sample are available, the system may use these instead of resampling. The duplicates must be analyzed and the results reported to the State within 14 days after completion of the composite analysis or before the holding time for the initial sample is exceeded whichever is sooner.

(iii) If the population served by the system is >3,300 persons, then compositing may only be permitted by the State at sampling points within a single system. In systems serving ≤3,300 persons, the State may permit compositing among different systems provided the 5-sample limit is maintained.

(11) Compliance with § 141.61(c) shall be determined based on the analytical results obtained at each sampling point. If one sampling point is in violation of an MCL, the system is in violation of the MCL.

(i) For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point.

(ii) Systems monitoring annually or less frequently whose sample result exceeds the regulatory detection level as defined by paragraph (h)(18) of this section must begin quarterly sampling. The system will not be considered in violation of the MCL until it has completed one year of quarterly sampling.

(iii) If any sample result will cause the running annual average to exceed the MCL at any sampling point, the system is out of compliance with the MCL immediately.

(iv) If a system fails to collect the required number of samples, compliance will be based on the total number of samples collected.

(v) If a sample result is less than the detection limit, zero will be used to calculate the annual average.

(12) [Reserved]

(13) Analysis for PCBs shall be conducted as follows using the methods in paragraph (e) of this section:

(i) Each system which monitors for PCBs shall analyze each sample using either Method 508.1, 525.2, 508 or 505. Users of Method 505 may have more difficulty in achieving the required Aroclor detection limits than users of Methods 508.1, 525.2 or 508.

(ii) If PCBs (as one of seven Aroclors) are detected (as designated in this paragraph) in any sample analyzed using Method 505 or 508, the system shall reanalyze the sample using Method 508A to quantitate PCBs (as decachlorobiphenyl).

Aroclor Detection limit (mg/l)
1016 0.00008
1221 0.02
1232 0.0005
1242 0.0003
1248 0.0001
1254 0.0001
1260 0.0002

(iii) Compliance with the PCB MCL shall be determined based upon the quantitative results of analyses using Method 508A.

(14) If monitoring data collected after January 1, 1990, are generally consistent with the requirements of § 141.24(h), then the State may allow systems to use that data to satisfy the monitoring requirement for the initial compliance period beginning January 1, 1993.

(15) The State may increase the required monitoring frequency, where necessary, to detect variations within the system (e.g., fluctuations in concentration due to seasonal use, changes in water source).

(16) The State has the authority to determine compliance or initiate enforcement action based upon analytical results and other information compiled by their sanctioned representatives and agencies.

(17) Each public water system shall monitor at the time designated by the State within each compliance period.

(18) Detection as used in this paragraph shall be defined as greater than or equal to the following concentrations for each contaminant.

Contaminant Detection limit (mg/l)
Alachlor .0002
Aldicarb .0005
Aldicarb sulfoxide .0005
Aldicarb sulfone .0008
Atrazine .0001
Benzo[a]pyrene .00002
Carbofuran .0009
Chlordane .0002
Dalapon .001
1,2-Dibromo-3-chloropropane (DBCP) .00002
Di (2-ethylhexyl) adipate .0006
Di (2-ethylhexyl) phthalate .0006
Dinoseb .0002
Diquat .0004
2,4-D .0001
Endothall .009
Endrin .00001
Ethylene dibromide (EDB) .00001
Glyphosate .006
Heptachlor .00004
Heptachlor epoxide .00002
Hexachlorobenzene .0001
Hexachlorocyclopentadiene .0001
Lindane .00002
Methoxychlor .0001
Oxamyl .002
Picloram .0001
Polychlorinated biphenyls (PCBs) (as decachlorobiphenyl) .0001
Pentachlorophenol .00004
Simazine .00007
Toxaphene .001
2,3,7,8-TCDD (Dioxin) .000000005
2,4,5-TP (Silvex) .0002

(19) Anaylsis under this section shall only be conducted by laboratories that have received certification by EPA or the State and have met the following conditions:

(i) To receive certification to conduct analyses for the contaminants in § 141.61(c) the laboratory must:

(A) Analyze Performance Evaluation (PE) samples provided by EPA, the State, or by a third party (with the approval of the State or EPA) at least once a year by each method for which the laboratory desires certification.

(B) For each contaminant that has been included in the PE sample achieve quantitative results on the analyses that are within the following acceptance limits:

Contaminant Acceptance limits (percent)
DBCP ±40
EDB ±40.
Alachlor ±45.
Atrazine ±45.
Benzo[a]pyrene 2 standard deviations.
Carbofuran ±45.
Chlordane ±45.
Dalapon 2 standard deviations.
Di(2-ethylhexyl)adipate 2 standard deviations.
Di(2-ethylhexyl)phthalate 2 standard deviations.
Dinoseb 2 standard deviations.
Diquat 2 standard deviations.
Endothall 2 standard deviations.
Endrin ±30.
Glyphosate 2 standard deviations.
Heptachlor ±45.
Heptachlor epoxide ±45.
Hexachlorobenzene 2 standard deviations.
Hexachloro- cyclopentadiene 2 standard deviations.
Lindane ±45.
Methoxychlor ±45.
Oxamyl 2 standard deviations.
PCBs (as Decachlorobiphenyl) 0-200.
Picloram 2 standard deviations.
Simazine 2 standard deviations.
Toxaphene ±45.
Aldicarb 2 standard deviations.
Aldicarb sulfoxide 2 standard deviations.
Aldicarb sulfone 2 standard deviations.
Pentachlorophenol ±50.
2,3,7,8-TCDD (Dioxin) 2 standard deviations.
2,4-D ±50.
2,4,5-TP (Silvex) ±50.

(ii) [Reserved]

(20) All new systems or systems that use a new source of water that begin operation after January 22, 2004 must demonstrate compliance with the MCL within a period of time specified by the State. The system must also comply with the initial sampling frequencies specified by the State to ensure a system can demonstrate compliance with the MCL. Routine and increased monitoring frequencies shall be conducted in accordance with the requirements in this section.

(Approved by the Office of Management and Budget under control number 2040-0090)

[40 FR 59570, Dec. 24, 1975]

§ 141.25 Analytical methods for radioactivity.

(a) Analysis for the following contaminants shall be conducted to determine compliance with § 141.66 (radioactivity) in accordance with the methods in the following table, or the alternative methods listed in appendix A to subpart C this part, or their equivalent determined by EPA in accordance with § 141.27.

Contaminant Methodology Reference (Method of Page Number)
EPA1 EPA2 EPA3 EPA4 SM5 ASTM6 USGS7 DOE8 Other
Naturally Occurring:
Gross alpha11 and beta Evaporation 900.0 p. 1 00-01 p. 1 302, 7110 B, 7110 B-00 R-1120-76
Gross alpha11 Coprecipitation 00-02 7110 C, 7110 C-00
Radium 226 Radon emanation 903.1 p. 16 Ra-04 p. 19 305, 7500-Ra C, 7500-Ra C-01 D3454-97 R-1141-76 Ra-04 NY9,
Radiochemical 903.0 p. 13 Ra-03 304, 7500-Ra B, 7500-Ra B-01 D2460-97 R-1140-76 GA14
Radium 228 Radiochemical 904.0 p. 24 Ra-05 p. 19 7500-Ra D, 7500-Ra D-01 R-1142-76 NY9,
NJ10,
GA14
Uranium12 Radiochemical 908.0 7500-U B, 7500-U B-00
Fluorometric 908.1 7500-U C (17th Ed.) D2907-97 R-1180-76, R-1181-76 U-04
ICP-MS 200.813 3125 D5673-03
Alpha Spectrometry 00-07 p. 33 7500-U C (18th, 19th, or 20th Ed.), 7500-U C-00 D3972-97, 02 R-1182-76 U-02
Laser Phosphorimetry D5174-97, 02
Man-Made:
Radioactive Cesium Radiochemical 901.0 p. 4 7500-Cs B, 7500-Cs B-00 D2459-72 R-1111-76
Gamma Ray Spectrometry 901.1 p. 92 7120, 7120-97 D3649-91, 98a R-1110-76 4.5.2.3
Radioactive Iodine Radiochemical 902.0 p. 6 7500-I B, 7500-I B-00
p. 9 7500-I C, 7500-I C-00
7500-I D, 7500-I D-00 D3649-91, 98a
Gamma Ray Spectrometry 901.1 p. 92 7120, 7120-97 D4785-93, 00a 4.5.2.3
Radioactive Strontium 89, 90 Radiochemical 905.0 p. 29 Sr-04 p. 65 303, 7500-Sr B, 7500-Sr B-01 R-1160-76 Sr-01, Sr-02
Tritium Liquid Scintillation 906.0 p. 34 H-02 p. 87 306, 7500-3 H B, 7500-3 H B-00 D4107-91, 98 (Reapproved 2002) R-1171-76
Gamma Emitters Gamma Ray Spectrometry 901.1 p. 92 7120, 7120-97 D3649-91, 98a R-1110-76 Ga-01-R
902.0 7500-Cs B, 7500-Cs B-00 D4785-93, 00a
901.0 7500-I B, 7500-I B-00

(b) When the identification and measurement of radionuclides other than those listed in paragraph (a) of this section is required, the following references are to be used, except in cases where alternative methods have been approved in accordance with § 141.27.

(1) Procedures for Radiochemical Analysis of Nuclear Reactor Aqueous Solutions, H. L. Krieger and S. Gold, EPA-R4-73-014. USEPA, Cincinnati, Ohio, May 1973.

(2) HASL Procedure Manual, Edited by John H. Harley. HASL 300, ERDA Health and Safety Laboratory, New York, NY., 1973.

(c) For the purpose of monitoring radioactivity concentrations in drinking water, the required sensitivity of the radioanalysis is defined in terms of a detection limit. The detection limit shall be that concentration which can be counted with a precision of plus or minus 100 percent at the 95 percent confidence level (1.96σ where σ is the standard deviation of the net counting rate of the sample).

(1) To determine compliance with § 141.66(b), (c), and (e) the detection limit shall not exceed the concentrations in Table B to this paragraph.

Table B - Detection Limits for Gross Alpha Particle Activity, Radium 226, Radium 228, and Uranium

Contaminant Detection
limit
Gross alpha particle activity 3 pCi/L.
Radium 226 1 pCi/L.
Radium 228 1 pCi/L.
Uranium 1 µg/L

(2) To determine compliance with § 141.66(d) the detection limits shall not exceed the concentrations listed in Table C to this paragraph.

Table C - Detection Limits for Man-made Beta Particle and Photon Emitters

Radionuclide Detection limit
Tritium 1,000 pCi/1.
Strontium-89 10 pCi/1.
Strontium-90 2 pCi/1.
Iodine-131 1 pCi/1.
Cesium-134 10 pCi/1.
Gross beta 4 pCi/1.
Other radionuclides 1/10 of the applicable limit.

(d) To judge compliance with the maximum contaminant levels listed in § 141.66, averages of data shall be used and shall be rounded to the same number of significant figures as the maximum contaminant level for the substance in question.

(e) The State has the authority to determine compliance or initiate enforcement action based upon analytical results or other information compiled by their sanctioned representatives and agencies.

[41 FR 28404, July 9, 1976, as amended at 45 FR 57345, Aug. 27, 1980; 62 FR 10173, Mar. 5, 1997; 65 FR 76745, Dec. 7, 2000; 67 FR 65250, Oct. 23, 2002; 69 FR 38855, June 29, 2004; 69 FR 52180, Aug. 25, 2004; 72 FR 11245, Mar. 12, 2007; 74 FR 30958, June 29, 2009]

§ 141.26 Monitoring frequency and compliance requirements for radionuclides in community water systems.

(a) Monitoring and compliance requirements for gross alpha particle activity, radium-226, radium-228, and uranium.

(1) Community water systems (CWSs) must conduct initial monitoring to determine compliance with § 141.66(b), (c), and (e) by December 31, 2007. For the purposes of monitoring for gross alpha particle activity, radium-226, radium-228, uranium, and beta particle and photon radioactivity in drinking water, “detection limit” is defined as in § 141.25(c).

(i) Applicability and sampling location for existing community water systems or sources. All existing CWSs using ground water, surface water or systems using both ground and surface water (for the purpose of this section hereafter referred to as systems) must sample at every entry point to the distribution system that is representative of all sources being used (hereafter called a sampling point) under normal operating conditions. The system must take each sample at the same sampling point unless conditions make another sampling point more representative of each source or the State has designated a distribution system location, in accordance with paragraph (a)(2)(ii)(C) of this section.

(ii) Applicability and sampling location for new community water systems or sources. All new CWSs or CWSs that use a new source of water must begin to conduct initial monitoring for the new source within the first quarter after initiating use of the source. CWSs must conduct more frequent monitoring when ordered by the State in the event of possible contamination or when changes in the distribution system or treatment processes occur which may increase the concentration of radioactivity in finished water.

(2) Initial monitoring: Systems must conduct initial monitoring for gross alpha particle activity, radium-226, radium-228, and uranium as follows:

(i) Systems without acceptable historical data, as defined below, must collect four consecutive quarterly samples at all sampling points before December 31, 2007.

(ii) Grandfathering of data: States may allow historical monitoring data collected at a sampling point to satisfy the initial monitoring requirements for that sampling point, for the following situations.

(A) To satisfy initial monitoring requirements, a community water system having only one entry point to the distribution system may use the monitoring data from the last compliance monitoring period that began between June 2000 and December 8, 2003.

(B) To satisfy initial monitoring requirements, a community water system with multiple entry points and having appropriate historical monitoring data for each entry point to the distribution system may use the monitoring data from the last compliance monitoring period that began between June 2000 and December 8, 2003.

(C) To satisfy initial monitoring requirements, a community water system with appropriate historical data for a representative point in the distribution system may use the monitoring data from the last compliance monitoring period that began between June 2000 and December 8, 2003, provided that the State finds that the historical data satisfactorily demonstrate that each entry point to the distribution system is expected to be in compliance based upon the historical data and reasonable assumptions about the variability of contaminant levels between entry points. The State must make a written finding indicating how the data conforms to the these requirements.

(iii) For gross alpha particle activity, uranium, radium-226, and radium-228 monitoring, the State may waive the final two quarters of initial monitoring for a sampling point if the results of the samples from the previous two quarters are below the detection limit.

(iv) If the average of the initial monitoring results for a sampling point is above the MCL, the system must collect and analyze quarterly samples at that sampling point until the system has results from four consecutive quarters that are at or below the MCL, unless the system enters into another schedule as part of a formal compliance agreement with the State.

(3) Reduced monitoring: States may allow community water systems to reduce the future frequency of monitoring from once every three years to once every six or nine years at each sampling point, based on the following criteria.

(i) If the average of the initial monitoring results for each contaminant (i.e., gross alpha particle activity, uranium, radium-226, or radium-228) is below the detection limit specified in Table B, in § 141.25(c)(1), the system must collect and analyze for that contaminant using at least one sample at that sampling point every nine years.

(ii) For gross alpha particle activity and uranium, if the average of the initial monitoring results for each contaminant is at or above the detection limit but at or below1/2 the MCL, the system must collect and analyze for that contaminant using at least one sample at that sampling point every six years. For combined radium-226 and radium-228, the analytical results must be combined. If the average of the combined initial monitoring results for radium-226 and radium-228 is at or above the detection limit but at or below1/2 the MCL, the system must collect and analyze for that contaminant using at least one sample at that sampling point every six years.

(iii) For gross alpha particle activity and uranium, if the average of the initial monitoring results for each contaminant is above1/2 the MCL but at or below the MCL, the system must collect and analyze at least one sample at that sampling point every three years. For combined radium-226 and radium-228, the analytical results must be combined. If the average of the combined initial monitoring results for radium-226 and radium-228 is above1/2 the MCL but at or below the MCL, the system must collect and analyze at least one sample at that sampling point every three years.

(iv) Systems must use the samples collected during the reduced monitoring period to determine the monitoring frequency for subsequent monitoring periods (e.g., if a system's sampling point is on a nine year monitoring period, and the sample result is above1/2 MCL, then the next monitoring period for that sampling point is three years).

(v) If a system has a monitoring result that exceeds the MCL while on reduced monitoring, the system must collect and analyze quarterly samples at that sampling point until the system has results from four consecutive quarters that are below the MCL, unless the system enters into another schedule as part of a formal compliance agreement with the State.

(4) Compositing: To fulfill quarterly monitoring requirements for gross alpha particle activity, radium-226, radium-228, or uranium, a system may composite up to four consecutive quarterly samples from a single entry point if analysis is done within a year of the first sample. States will treat analytical results from the composited as the average analytical result to determine compliance with the MCLs and the future monitoring frequency. If the analytical result from the composited sample is greater than1/2 MCL, the State may direct the system to take additional quarterly samples before allowing the system to sample under a reduced monitoring schedule.

(5) A gross alpha particle activity measurement may be substituted for the required radium-226 measurement provided that the measured gross alpha particle activity does not exceed 5 pCi/l. A gross alpha particle activity measurement may be substituted for the required uranium measurement provided that the measured gross alpha particle activity does not exceed 15 pCi/l. The gross alpha measurement shall have a confidence interval of 95% (1.65σ, where σ is the standard deviation of the net counting rate of the sample) for radium-226 and uranium. When a system uses a gross alpha particle activity measurement in lieu of a radium-226 and/or uranium measurement, the gross alpha particle activity analytical result will be used to determine the future monitoring frequency for radium-226 and/or uranium. If the gross alpha particle activity result is less than detection,1/2 the detection limit will be used to determine compliance and the future monitoring frequency.

(b) Monitoring and compliance requirements for beta particle and photon radioactivity. To determine compliance with the maximum contaminant levels in § 141.66(d) for beta particle and photon radioactivity, a system must monitor at a frequency as follows:

(1) Community water systems (both surface and ground water) designated by the State as vulnerable must sample for beta particle and photon radioactivity. Systems must collect quarterly samples for beta emitters and annual samples for tritium and strontium-90 at each entry point to the distribution system (hereafter called a sampling point), beginning within one quarter after being notified by the State. Systems already designated by the State must continue to sample until the State reviews and either reaffirms or removes the designation.

(i) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at a sampling point has a running annual average (computed quarterly) less than or equal to 50 pCi/L (screening level), the State may reduce the frequency of monitoring at that sampling point to once every 3 years. Systems must collect all samples required in paragraph (b)(1) of this section during the reduced monitoring period.

(ii) For systems in the vicinity of a nuclear facility, the State may allow the CWS to utilize environmental surveillance data collected by the nuclear facility in lieu of monitoring at the system's entry point(s), where the State determines if such data is applicable to a particular water system. In the event that there is a release from a nuclear facility, systems which are using surveillance data must begin monitoring at the community water system's entry point(s) in accordance with paragraph (b)(1) of this section.

(2) Community water systems (both surface and ground water) designated by the State as utilizing waters contaminated by effluents from nuclear facilities must sample for beta particle and photon radioactivity. Systems must collect quarterly samples for beta emitters and iodine-131 and annual samples for tritium and strontium-90 at each entry point to the distribution system (hereafter called a sampling point), beginning within one quarter after being notified by the State. Systems already designated by the State as systems using waters contaminated by effluents from nuclear facilities must continue to sample until the State reviews and either reaffirms or removes the designation.

(i) Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples or the analysis of a composite of three monthly samples. The former is recommended.

(ii) For iodine-131, a composite of five consecutive daily samples shall be analyzed once each quarter. As ordered by the State, more frequent monitoring shall be conducted when iodine-131 is identified in the finished water.

(iii) Annual monitoring for strontium-90 and tritium shall be conducted by means of the analysis of a composite of four consecutive quarterly samples or analysis of four quarterly samples. The latter procedure is recommended.

(iv) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity at a sampling point has a running annual average (computed quarterly) less than or equal to 15 pCi/L (screening level), the State may reduce the frequency of monitoring at that sampling point to every 3 years. Systems must collect the same type of samples required in paragraph (b)(2) of this section during the reduced monitoring period.

(v) For systems in the vicinity of a nuclear facility, the State may allow the CWS to utilize environmental surveillance data collected by the nuclear facility in lieu of monitoring at the system's entry point(s), where the State determines if such data is applicable to a particular water system. In the event that there is a release from a nuclear facility, systems which are using surveillance data must begin monitoring at the community water system's entry point(s) in accordance with paragraph (b)(2) of this section.

(3) Community water systems designated by the State to monitor for beta particle and photon radioactivity can not apply to the State for a waiver from the monitoring frequencies specified in paragraph (b)(1) or (b)(2) of this section.

(4) Community water systems may analyze for naturally occurring potassium-40 beta particle activity from the same or equivalent sample used for the gross beta particle activity analysis. Systems are allowed to subtract the potassium-40 beta particle activity value from the total gross beta particle activity value to determine if the screening level is exceeded. The potassium-40 beta particle activity must be calculated by multiplying elemental potassium concentrations (in mg/L) by a factor of 0.82.

(5) If the gross beta particle activity minus the naturally occurring potassium-40 beta particle activity exceeds the appropriate screening level, an analysis of the sample must be performed to identify the major radioactive constituents present in the sample and the appropriate doses must be calculated and summed to determine compliance with § 141.66(d)(1), using the formula in § 141.66(d)(2). Doses must also be calculated and combined for measured levels of tritium and strontium to determine compliance.

(6) Systems must monitor monthly at the sampling point(s) which exceed the maximum contaminant level in § 141.66(d) beginning the month after the exceedance occurs. Systems must continue monthly monitoring until the system has established, by a rolling average of 3 monthly samples, that the MCL is being met. Systems who establish that the MCL is being met must return to quarterly monitoring until they meet the requirements set forth in paragraph (b)(1)(i) or (b)(2)(iv) of this section.

(c) General monitoring and compliance requirements for radionuclides.

(1) The State may require more frequent monitoring than specified in paragraphs (a) and (b) of this section, or may require confirmation samples at its discretion. The results of the initial and confirmation samples will be averaged for use in compliance determinations.

(2) Each public water systems shall monitor at the time designated by the State during each compliance period.

(3) Compliance: Compliance with § 141.66 (b) through (e) will be determined based on the analytical result(s) obtained at each sampling point. If one sampling point is in violation of an MCL, the system is in violation of the MCL.

(i) For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point. If the average of any sampling point is greater than the MCL, then the system is out of compliance with the MCL.

(ii) For systems monitoring more than once per year, if any sample result will cause the running average to exceed the MCL at any sample point, the system is out of compliance with the MCL immediately.

(iii) Systems must include all samples taken and analyzed under the provisions of this section in determining compliance, even if that number is greater than the minimum required.

(iv) If a system does not collect all required samples when compliance is based on a running annual average of quarterly samples, compliance will be based on the running average of the samples collected.

(v) If a sample result is less than the detection limit, zero will be used to calculate the annual average, unless a gross alpha particle activity is being used in lieu of radium-226 and/or uranium. If the gross alpha particle activity result is less than detection,1/2 the detection limit will be used to calculate the annual average.

(4) States have the discretion to delete results of obvious sampling or analytic errors.

(5) If the MCL for radioactivity set forth in § 141.66 (b) through (e) is exceeded, the operator of a community water system must give notice to the State pursuant to § 141.31 and to the public as required by subpart Q of this part.

[65 FR 76745, Dec. 7, 2000, as amended at 69 FR 38855, June 29, 2004]

§ 141.27 Alternate analytical techniques.

(a) With the written permission of the State, concurred in by the Administrator of the U.S. EPA, an alternate analytical technique may be employed. An alternate technique shall be accepted only if it is substantially equivalent to the prescribed test in both precision and accuracy as it relates to the determination of compliance with any MCL. The use of the alternate analytical technique shall not decrease the frequency of monitoring required by this part.

[45 FR 57345, Aug. 27, 1980]

§ 141.28 Certified laboratories.

(a) For the purpose of determining compliance with § 141.21 through 141.27, 141.30, 141.40, 141.74, 141.89 and 141.402, samples may be considered only if they have been analyzed by a laboratory certified by the State except that measurements of alkalinity, calcium, conductivity, disinfectant residual, orthophosphate, pH, silica, temperature and turbidity may be performed by any person acceptable to the State.

(b) Nothing in this part shall be construed to preclude the State or any duly designated representative of the State from taking samples or from using the results from such samples to determine compliance by a supplier of water with the applicable requirements of this part.

[45 FR 57345, Aug. 27, 1980; 47 FR 10999, Mar. 12, 1982, as amended at 59 FR 34323, July 1, 1994; 64 FR 67465, Dec. 1, 1999; 71 FR 65651, Nov. 8, 2006]

§ 141.29 Monitoring of consecutive public water systems.

When a public water system supplies water to one or more other public water systems, the State may modify the monitoring requirements imposed by this part to the extent that the interconnection of the systems justifies treating them as a single system for monitoring purposes. Any modified monitoring shall be conducted pursuant to a schedule specified by the State and concurred in by the Administrator of the U.S. Environmental Protection Agency.

Appendix A to Subpart C of Part 141 - Alternative Testing Methods Approved for Analyses Under the Safe Drinking Water Act

Only the editions stated in the following table are approved.

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.21(f)(3)

Organism Methodology SM 21st Edition1 SM 22nd Edition28 SM Online3 Other
Total Coliforms Total Coliform Fermentation Technique 9221 A, B 9221 A, B 9221 A,B-06
Total Coliform Membrane Filter Technique 9222 A, B, C
Presence-Absence (P-A) Coliform Test 9221 D
ONPG-MUG Test 9223 9223 B 9223 B-04
ColitagTM Modified ColitagTM13
Tecta EC/TC33

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.21(f)(5)

Organism Methodology SM 22nd Edition28 SM Online3
Fecal Coliforms Fecal Coliform Procedure 9221 E 9221 E-06

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.21(f)(6)

Organism Methodology SM 20th
Edition6
SM 21st
Edition1
SM 22nd
Edition28
SM Online3 Other
E.coli ONPG-MUG Test 9223 B 9223 B 9223 B 9223 B-97, B-04
ColitagTM Modified ColitagTM13
Tecta EC/TC33

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.23(k)(1)

Contaminant Methodology EPA method SM 21st
edition1
SM 22nd
edition28
SM 23rd
edition49
SM Online3 ASTM4 Other
Alkalinity Titrimetric 2320 B 2320 B 2320 B D1067-06 B, 11 B, 16 B
Antimony Hydride - Atomic Absorption D 3697-07, -12, -17
Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Arsenic Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10 D 2972-08 C, -15 C
Hydride Atomic Absorption 3114 B 3114 B 3114 B 3114 B-09 D 2972-08 B, -15 B
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Barium Inductively Coupled Plasma 3120 B 3120 B 3120 B
Atomic Absorption; Direct 3111 D 3111 D 3111 D
Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Beryllium Inductively Coupled Plasma 3120 B 3120 B 3120 B
Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10 D 3645-08 B, -15 B
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Cadmium Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Calcium EDTA titrimetric 3500-Ca B 3500-Ca B 3500-Ca B D 511-09, -14 A
Atomic Absorption; Direct Aspiration 3111 B 3111 B 3111 B D 511-09, -14 B
Inductively Coupled Plasma 3120 B 3120 B 3120 B
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Ion Chromatography D 6919-09, -17
Chromium Inductively Coupled Plasma 3120 B 3120 B 3120 B
Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Copper Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10 D 1688-07, -12 C, -17 C
Atomic Absorption; Direct Aspiration 3111 B 3111 B 3111 B D 1688-07, -12 A, -17 A
Inductively Coupled Plasma 3120 B 3120 B 3120 B
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Colorimetry Hach Method 8026.35
Hach Method 1027236
Cyanide Manual Distillation with MgCl2 followed by: 4500-CN− C 4500-CN− C 4500-CN− C 4500-CN− C-99 D 2036-06 A
Spectrophotometric, Amenable 4500-CN− G 4500-CN− G 4500-CN− G D 2036-06 B
Spectrophotometric Manual 4500-CN− E 4500-CN− E 4500-CN− E D2036-06 A
Selective Electrode 4500-CN− F 4500-CN− F 4500-CN− F
Gas Chromatography/Mass Spectrometry Headspace ME355.01.7
Fluoride Ion Chromatography 4110 B 4110 B 4110 B D 4327-11, -17
Manual Distillation; Colorimetric SPADNS 4500-F− B, D 4500-F− B, D 4500-F− B, D
Manual Electrode 4500-F− C 4500-F− C 4500-F− C D 1179-04, 10 B, 16 B
Automated Alizarin 4500-F− E 4500-F− E 4500-F− E
Arsenite-Free Colorimetric SPADNS Hach SPADNS. 2 Method 10225.22
Lead Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10 D 3559-08 D, -15 D
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Differential Pulse Anodic Stripping Voltametry Method 1001, Rev. 1.157
Magnesium Atomic Absorption 3111 B 3111 B 3111 B D 511-09, -14 B
Inductively Coupled Plasma 3120 B 3120 B 3120 B
Complexation Titrimetric Methods 3500-Mg B 3500-Mg B 3500-Mg B D 511-09, -14 A
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Ion Chromatography D 6919-09, -17
Mercury Manual, Cold Vapor 3112 B 3112 B 3112 B 3112 B-09 D 3223-12, -17
Nickel Inductively Coupled Plasma 3120 B 3120 B 3120 B
Atomic Absorption; Direct 3111 B 3111 B 3111 B
Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Nitrate Ion Chromatography 4110 B 4110 B 4110 B D 4327-11, -17
Automated Cadmium Reduction 4500-NO3− F 4500-NO3− F 4500-NO3− F
Manual Cadmium Reduction 4500-NO3− E 4500-NO3− E 4500-NO3− E
Ion Selective Electrode 4500-NO3− D 4500-NO3− D 4500-NO3− D
Reduction/Colorimetric Systea Easy (1-Reagent).8
NECi Nitrate-Reductase.40
Colorimetric; Direct Hach TNTplusTM 835/836 Method 10206.23
Capillary Ion Electrophoresis D 6508-15
Nitrite Ion Chromatography 4110 B 4110 B 4110 B D 4327-11, -17
Automated Cadmium Reduction 4500-NO3− F 4500-NO3− F 4500-NO3− F
Manual Cadmium Reduction 4500-NO3− E 4500-NO3− E 4500-NO3− E
Spectrophotometric 4500-NO2− B 4500-NO2− B 4500-NO2− B
Reduction/Colorimetric Systea Easy (1-Reagent).8
NECi Nitrate-Reductase.40
Capillary Ion Electrophoresis D 6508-15
Ortho-phosphate Ion Chromatography 4110 B 4110 B 4110 B D 4327-11, -17
Colorimetric, ascorbic acid, single reagent 4500-P E 4500-P E 4500-P E 4500-P E-99
Colorimetric, Automated, Ascorbic Acid 4500-P F 4500-P F 4500-P F 4500-P F-99 Thermo Fisher Discrete Analyzer.41
Capillary Ion Electrophoresis D 6508-15
pH Electrometric 150.348 4500-H + B 4500-H + B 4500-H + B D 1293-12, -18
Selenium Hydride-Atomic Absorption 3114 B 3114 B 3114 B 3114 B-09 D 3859-08 A, -15 A
Atomic Absorption; Furnace 3113 B 3113 B 3113 B 3113 B-04, B-10 D 3859-08 B, -15 B
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Silica Colorimetric D859-05, 10, 16
Molybdosilicate 4500-SiO2 C 4500-SiO2 C 4500-SiO2 C
Heteropoly blue 4500-SiO2 D 4500-SiO2 D 4500-SiO2 D
Automated for Molybdate-reactive Silica 4500-SiO2 E 4500-SiO2 E 4500-SiO2 E
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Inductively Coupled Plasma 3120 B 3120 B 3120 B
Sodium Atomic Absorption; Direct Aspiration 3111 B 3111 B 3111 B
Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.22
Ion Chromatography D 6919-09, -17

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.24(e)(1)

Contaminant Methodology EPA method SM 21st edition1 SM 22nd edition28, SM 23rd edition49 SM online3 Other
Benzene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Carbon tetrachloride Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Chlorobenzene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,2-Dichlorobenzene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,4-Dichlorobenzene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,2-Dichloroethane Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
cis-Dichloroethylene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
trans-Dichloroethylene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Dichloromethane Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,2-Dichloropropane Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Ethylbenzene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Styrene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Tetrachloroethylene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,1,1-Trichloroethane Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Trichloroethylene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Toluene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,2,4-Trichlorobenzene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,1-Dichloroethylene Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
1,1,2-Trichlorethane Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Vinyl chloride Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
Xylenes (total) Purge & Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29
2,4-D Gas Chromatography/Electron Capture Detection (GC/ECD) 6640 B 6640 B 6640 B-01, B-06
2,4,5-TP (Silvex) Gas Chromatography/Electron Capture Detection (GC/ECD) 6640 B 6640 B 6640 B-01, B-06
Alachlor Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.324
Atrazine Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS) 536.25
Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.324, 523.26
Benzo(a)pyrene Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Carbofuran High-performance liquid chromatography (HPLC) with post-column derivatization and fluorescence detection 6610 B 6610 B 6610 B-04
Chlordane Liquid Chromatography/Mass Spectrometry ME 531.58
Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Dalapon Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS) 557.14
Gas Chromatography/Electron Capture Detection (GC/ECD) 6640 B 6640 B 6640 B-01, B-06
Di(2-ethylhexyl)adipate Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Di(2-ethylhexyl)phthalate Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Dibromochloropropane (DBCP) Purge &Trap/Gas Chromatography/Mass Spectrometry 524.3.9
Dinoseb Gas Chromatography/Electron Capture Detection (GC/ECD) 6640 B 6640 B 6640 B-01, B-06
Endrin Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Ethyl dibromide (EDB) Purge &Trap/Gas Chromatography/Mass Spectrometry 524.3.9
Glyphosate High-Performance Liquid Chromatography (HPLC) with Post-Column Derivatization and Fluorescence Detection 6651 B 6651 B 6651 B-00, B-05
Heptachlor Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Heptachlor Epoxide Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Hexachlorobenzene Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Hexachlorocyclo-pentadiene Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Lindane Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Methoxychlor Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Oxamyl High-performance liquid chromatography (HPLC) with post-column derivatization and fluorescence detection 6610 B 6610 B 6610 B-04
Liquid Chromatography/Mass Spectrometry ME 531.58
PCBs (as Aroclors) Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Pentachlorophenol Gas Chromatography/Electron Capture Detection (GC/ECD) 6640 B 6640 B 6640 B-01, B-06
Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Picloram Gas Chromatography/Electron Capture Detection (GC/ECD) 6640 B 6640 B 6640 B-01, B-06
Simazine Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS) 536.25
Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.324, 523.26
Toxaphene Solid Phase Extraction/Gas Chromatography/Mass Spectrometry (GC/MS) 525.3.24
Total Trihalomethanes Purge &Trap/Gas Chromatography/Mass Spectrometry 524.39, 524.4.29

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.25(a)

Contaminant Methodology EPA
method
SM 21st
edition1
SM 22nd
edition,28
SM 23rd
edition49
ASTM4 SM Online3
Naturally Occurring:
Gross alpha and beta Evaporation 900.0, Rev. 1.050 7110 B 7110 B
Liquid Scintillation D 7283-17 7110 D-17.
Gross alpha Coprecipitation 7110 C 7110 C
Radium 226 Radon emanation 903.1, Rev. 1.053 7500-Ra C 7500-Ra C D 3454-05, -18
Radiochemical 903.0, Rev. 1.054 7500-Ra B 7500-Ra B D 2460-07
Gamma Spectrometry 7500-Ra E 7500-Ra E-07.
Radium 228 Radiochemical 7500-Ra D 7500-Ra D
Gamma Spectrometry 7500Ra-E 7500-Ra E-07.
Uranium Radiochemical 7500-U B 7500-U B
ICP-MS 3125 D 5673-05, 10, 16
Alpha spectrometry 7500-U C 7500-U C D 3972-09
Laser Phosphorimetry D 5174-07
Alpha Liquid Scintillation Spectrometry D 6239-09
Man-Made:
Radioactive Cesium Radiochemical 7500-Cs B 7500-Cs B
Gamma Ray Spectrometry 7120 7120 D 3649-06
Radioactive Iodine Radiochemical 7500-I B 7500-I B D 3649-06
7500-I C 7500-I C
7500-I D 7500-I D
Gamma Ray Spectrometry 7120 7120 D 4785-08
Radioactive Strontium 89, 90 Radiochemical 7500-Sr B 7500-Sr B
Tritium Liquid Scintillation 7500-3H B 7500-3H B D 4107-08
Gamma Emitters Gamma Ray 7120 7120 D 3649-06
Spectrometry 7500-Cs B 7500-Cs B D 4785-08
7500-I B 7500-I B

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.74(a)(1)

Organism Methodology SM 21st
edition1
SM 22nd
edition28
SM 23rd
edition49
SM Online3 Other
Total Coliform Total Coliform Fermentation Technique 9221 A, B, C 9221 A, B, C 9221 A, B, C 9221 A,B,C-06
Total Coliform Membrane Filter Technique 9222 A, B, C 9222 A, B, C.
ONPG-MUG Test 9223 9223 B 9223 B 9223 B-04.
Fecal Coliforms Fecal Coliform Procedure 9221 E 9221 E 9221 E 9221 E-06.
Fecal Coliform Filter Procedure 9222 D 9222 D 9222 D 9222 D-06.
Heterotrophic bacteria Pour Plate Method 9215 B 9215 B 9215 B 9215 B-04.
Turbidity Nephelometric Method 2130 B 2130 B 2130 B Hach Method 8195, Rev. 3.0.52
Laser Nephelometry (on-line) Mitchell M5271,10 Mitchell M5331, Rev. 1.2,42 Lovibond PTV 6000.46
LED Nephelometry (on-line) Mitchell M5331,11
Mitchell M5331, Rev. 1.2,42 Lovibond PTV 2000.45
LED Nephelometry (on-line) AMI Turbiwell,15 Lovibond PTV 1000.44
LED Nephelometry (portable) Orion AQ4500.12
360° Nephelometry Hach Method 10258 Rev. 1.0,39 Hach Method 10258, Rev. 2.0.51

Alternative Testing Methods for Disinfectant Residuals Listed at 40 CFR 141.74(a)(2)

Residual Methodology EPA methods SM 21st
edition1
SM 22nd
edition28, SM 23rd edition49
ASTM4 Other
Free Chlorine Amperometric Titration 4500-Cl D 4500-Cl D D 1253-08, -14
DPD Ferrous Titrimetric 4500-Cl F 4500-Cl F
DPD Colorimetric 4500-Cl G 4500-Cl G Hach Method 10260.31
Indophenol Colorimetric Hach Method 10241.34
Syringaldazine (FACTS) 4500-Cl H 4500-Cl H
On-line Chlorine Analyzer 334.016
Amperometric Sensor ChloroSense17, ChloroSense Rev. 1.1.59
Total Chlorine Amperometric Titration 4500-Cl D 4500-Cl D D 1253-08, -14
Amperometric Titration (Low level measurement) 4500-Cl E 4500-Cl E
DPD Ferrous Titrimetric 4500-Cl F 4500-Cl F
DPD Colorimetric 4500-Cl G 4500-Cl G Hach Method 10260.31
Iodometric Electrode 4500-Cl I 4500-Cl I
On-line Chlorine Analyzer 334.016
Amperometric Sensor ChloroSense17, ChloroSense, Rev. 1.1.59
Indophenol Colorimetric 127.55
Chlorine Dioxide Amperometric Titration 4500-ClO2 C 4500-ClO2 C
Amperometric Titration 4500-ClO2 E 4500-ClO2 E
Amperometric Sensor ChlordioX Plus32, ChlordioX Plus, Rev. 1.1.60
Ozone Indigo Method 4500-O3 B 4500-O3 B

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.131(b)(1)

Contaminant Methodology EPA method ASTM4 SM online3 SM 21st edition1 SM 22nd edition,28
SM 23rd edition49
Other
TTHM P&T/GC/MS 524.3,9 524.4.29
HAA5 LLE (diazomethane)/GC/ECD 6251 B-07 6251 B 6251 B.
Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS) 557.14
Two-Dimensional Ion Chromatography (IC) with Suppressed Conductivity Detection Thermo Fisher 557.1.47
Bromate Two-Dimensional Ion Chromatography (IC) 302.0.18
Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS) 557.14
Chemically Suppressed Ion Chromatography D 6581-08 A.
Electrolytically Suppressed Ion Chromatography D 6581-08 B.
Chlorite Chemically Suppressed Ion Chromatography D 6581-08 A.
Electrolytically Suppressed Ion Chromatography D 6581-08 B.
Chlorite - daily monitoring as prescribed in 40 CFR 141.132(b)(2)(i)(A) Amperometric Titration
Amperometric Sensor


4500-ClO2 E
4500-ClO2 E

ChlordioX Plus32, ChlordioX Plus, Rev. 1.1.60

Alternative Testing Methods for Disinfectant Residuals Listed at 40 CFR 141.131(c)(1)

Residual Methodology SM 21st
edition1
SM 22nd
edition,28
SM 23rd
edition49
ASTM4 Other
Free Chlorine Amperometric Titration 4500-Cl D 4500-Cl D D 1253-08, -14
DPD Ferrous Titrimetric 4500-Cl F 4500-Cl F
DPD Colorimetric 4500-Cl G 4500-Cl G Hach Method 10260.31
Indophenol Colorimetric Hach Method 10241.34
Syringaldazine (FACTS) 4500-Cl H 4500-Cl H
Amperometric Sensor ChloroSense17, ChloroSense, Rev. 1.1.59
On-line Chlorine Analyzer EPA 334.0.16
Combined Chlorine Amperometric Titration 4500-Cl D 4500-Cl D D 1253-08, -14.
DPD Ferrous Titrimetric 4500-Cl F 4500-Cl F
DPD Colorimetric 4500-Cl G 4500-Cl G Hach Method 10260.31
Total Chlorine Amperometric Titration 4500-Cl D 4500-Cl D D 1253-08, -14
Low level Amperometric Titration 4500-Cl E 4500-Cl E
DPD Ferrous Titrimetric 4500-Cl F 4500-Cl F
DPD Colorimetric 4500-Cl G 4500-Cl G Hach Method 10260.31
Iodometric Electrode 4500-Cl I 4500-Cl I
Amperometric Sensor ChloroSense,17 ChloroSense, Rev. 1.1.59
On-line Chlorine Analyzer EPA 334.0.16
Chlorine Dioxide Amperometric Method II 4500-ClO2 E 4500-ClO2 E
Amperometric Sensor ChlordioX Plus,32 ChlordioX Plus, Rev. 1.1.60

Alternative Testing Methods for Disinfectant Residuals Listed at 40 CFR 141.131(c)(2), If Approved by the State

Residual Methodology Method
Free Chlorine Test Strips Method D99-0035

Alternative Testing Methods for Parameters Listed at 40 CFR 141.131(d)

Parameter Methodology SM 21st edition1 SM 22nd edition28 SM 23rd edition49 SM online3 EPA Other
Total Organic Carbon (TOC) High Temperature Combustion 5310 B 5310 B 5310 B 415.3, Rev 1.2.19
Persulfate-Ultraviolet or Heated Persulfate Oxidation 5310 C 5310 C 5310 C 415.3, Rev 1.2.19 Hach Method 10267.38
Wet Oxidation 5310 D 5310 D 415.3, Rev 1.2.19
Ozone Oxidation Hach Method 10261.37
Specific Ultraviolet Absorbance (SUVA) Calculation using DOC and UV254 data 415.3, Rev 1.2.19
Dissolved Organic Carbon (DOC) High Temperature Combustion 5310 B 5310 B 5310 B 415.3, Rev 1.2.19
Persulfate-Ultraviolet or Heated Persulfate Oxidation 5310 C 5310 C 5310 C 415.3, Rev 1.2.19
Wet Oxidation 5310 D 5310 D 415.3, Rev 1.2.19
Ultraviolet absorption at 254 nm (UV254) Spectrophotometry 5910 B 5910 B 5910 B 5910 B-11 415.3, Rev 1.2.19

Alternative Testing Methods With MRL ≤0.0010 mg/L for Monitoring Listed at 40 CFR 141.132(b)(3)(ii)(B)

Contaminant Methodology EPA method
Bromate Two-Dimensional Ion Chromatography (IC) 302.018
Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS) 55714

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.402(c)(2)

Organism Methodology SM 20th
edition6
SM 21st
edition1
SM 22nd
edition28
SM 23rd
edition49
SM online3 Other
E. coli Colilert 9223 B 9223 B 9223 B 9223 B-97, B-04
Colisure 9223 B 9223 B 9223 B 9223 B-97, B-04
Colilert-18 9223 B 9223 B 9223 B 9223 B 9223 B-97, B-04
Readycult® Readycult®.20
Colitag Modified ColitagTM13, Modified ColitagTM, Version 2.0.61
Chromocult® Chromocult®.21
EC-MUG 9221 F 9221 F 9221 F-06
NA-MUG 9222 I
m-ColiBlue24 Test 9222 J
Tecta EC/TC33 43
RAPID'E.coli 256
Enterococci Multiple-Tube Technique 9230 B-04.
Membrane Filter Techniques 9230 C.
Fluorogenic Substrate Enterococcus Test (using Enterolert) 9230 D.
Coliphage Two-Step Enrichment Presence-Absence Procedure Fast Phage.30

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.704(a)

Organism Methodology EPA Method
Cryptosporidium Filtration/Immunomagnetic Separation/Immunofluorescence Assay Microscopy 1623.127

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.704(b)

Organism Methodology SM 20th edition6
E. coli Membrane Filtration, Two Step 9222 D/9222 G

Alternative Testing Methods for Contaminants Listed at 40 CFR 141.852(a)(5)

Organism Methodology
category
Method SM 20th, 21st editions1 6 SM 22nd
edition28
SM 23rd
edition49
SM online3
Total Coliforms Lactose Fermentation Methods Standard Total Coliform Fermentation Technique 9221 B.1, B.2 9221 B.1, B.2, B.3, B.4 9221 B.1, B.2-06.
Presence-Absence (P-A) Coliform Test 9221 D.1, D.2, D.3
Membrane Filtration Methods Standard Total Coliform Membrane Filter Procedure using Endo Media 9222 B, C.
Simultaneous Detection of Total Coliforms and E. coli by Dual Chromogen Membrane Filter Procedure (using mColiBlue24 medium) 9222 J.
Simultaneous Detection of Total Coliform Bacteria and Escherichia coli Using RAPID'E.coli (REC2) in Drinking Water.56
Enzyme Substrate Methods Colilert® 9223 B 9223 B 9223 B-04
Colisure® 9223 B 9223 B 9223 B-04.
Colilert-18 9223 B 9223 B 9223 B 9223 B-04.
Tecta EC/TC.33 43
Modified ColitagTM, Version 2.0.61
Escherichia coli Escherichia coli Procedure (following Lactose Fermentation Methods) EC-MUG medium 9221 F.1 9221 F.1 9221 F.1-06.
Escherichia coli Partitioning Methods (following Membrane Filtration Methods) EC broth with MUG (EC-MUG) 9222 H.
NA-MUG medium 9222 I.
Simultaneous Detection of Total Coliforms and E. coli by Dual Chromogen Membrane Filter Procedure mColiBlue24 medium 9222 J.
Membrane Filtration Method Simultaneous Detection of Total Coliform Bacteria and Escherichia coli Using RAPID'E.coli (REC2) in Drinking Water.56
Enzyme Substrate Methods Colilert® 9223 B 9223 B 9223 B-04.
Colisure® 9223 B 9223 B 9223 B-04.
Colilert-18 9223 B 9223 B 9223 B 9223 B-04.
Tecta EC/TC.33 43
Modified ColitagTM, Version 2.0.61

Alternative Testing Methods for Contaminants Listed at 40 CFR 143.4(b)

Contaminant Methodology EPA method ASTM4 SM 21st
edition1
SM 22nd
edition,28
SM 23rd
edition49
SM online3
Aluminum Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2.2
Atomic Absorption; Direct 3111 D 3111 D.
Atomic Absorption; Furnace 3113 B 3113 B 3113 B-04, B-10.
Inductively Coupled Plasma 3120 B 3120 B.
Chloride Silver Nitrate Titration D 512-04 B, 12 B 4500-Cl B 4500-Cl B
Ion Chromatography D 4327-11, -17 4110 B 4110 B
Potentiometric Titration 4500-Cl D 4500-Cl D
Color Visual Comparison 2120 B 2120 B.
Foaming Agents Methylene Blue Active Substances (MBAS) 5540 C 5540 C.
Iron Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2.2
Atomic Absorption; Direct 3111 B 3111 B.
Atomic Absorption; Furnace 3113 B 3113 B 3113 B-04, B-10.
Inductively Coupled Plasma 3120 B 3120 B.
Manganese Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2.2
Atomic Absorption; Direct 3111 B 3111 B.
Atomic Absorption; Furnace 3113 B 3113 B 3113 B-04, B-10.
Inductively Coupled Plasma 3120 B 3120 B.
Odor Threshold Odor Test 2150 B 2150 B.
Silver Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2.2
Atomic Absorption; Direct 3111 B 3111 B.
Atomic Absorption; Furnace 3113 B 3113 B 3113 B-04, B-10.
Inductively Coupled Plasma 3120 B 3120 B.
Sulfate Ion Chromatography D 4327-11, -17 4110 B 4110 B
Gravimetric with ignition of residue 4500-SO4 2 C 4500-SO4 2 C 4500-SO4 2 C-97.
Gravimetric with drying of residue 4500-SO4 2 D 4500-SO4 2 D 4500-SO4 2 D-97.
Turbidimetric method D 516-07, 11, 16 4500-SO4 2 E 4500-SO4 2 E 4500-SO4 2 E-97.
Automated methylthymol blue method 4500-SO4 2 F 4500-SO4 2 F 4500-SO4 2 F-97.
Total Dissolved Solids Total Dissolved Solids Dried at 180 deg C 2540 C 2540 C.
Zinc Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2.2
Atomic Absorption; Direct Aspiration 3111 B 3111 B.
Inductively Coupled Plasma 3120 B 3120 B.

[74 FR 38353, Aug. 3, 2009, as amended at 74 FR 57914, Nov. 10, 2009; 74 FR 63069, Dec. 2, 2009; 75 FR 32299, June 8, 2010; 76 FR 37018, June 24, 2011; 77 FR 38527, June 28, 2012; 78 FR 32565, May 31, 2013; 78 FR 37463, June 21, 2013; 79 FR 35086, June 19, 2014; 79 FR 36428, June 27, 2014; 81 FR 46844, July 19, 2016; 82 FR 34867, July 27, 2017; 83 FR 51644, Oct. 12, 2018; 83 FR 54676, Oct. 31, 2018; 86 FR 28284, May 26, 2021; 86 FR 29526, June 2, 2021]

Subpart D - Reporting and Recordkeeping
§ 141.31 Reporting requirements.

(a) Except where a shorter period is specified in this part, the supplier of water shall report to the State the results of any test measurement or analysis required by this part within

(1) The first ten days following the month in which the result is received, or

(2) the first ten days following the end of the required monitoring period as stipulated by the State, whichever of these is shortest.

(b) Except where a different reporting period is specified in this part, the supplier of water must report to the State within 48 hours the failure to comply with any national primary drinking water regulation (including failure to comply with monitoring requirements) set forth in this part.

(c) The supplier of water is not required to report analytical results to the State in cases where a State laboratory performs the analysis and reports the results to the State office which would normally receive such notification from the supplier.

(d) The public water system, within 10 days of completing the public notification requirements under subpart Q of this part for the initial public notice and any repeat notices, must submit to the primacy agency a certification that it has fully complied with the public notification regulations. The public water system must include with this certification a representative copy of each type of notice distributed, published, posted, and made available to the persons served by the system and to the media.

(e) The water supply system shall submit to the State within the time stated in the request copies of any records required to be maintained under § 141.33 hereof or copies of any documents then in existence which the State or the Administrator is entitled to inspect pursuant to the authority of section 1445 of the Safe Drinking Water Act or the equivalent provisions of State law.

[40 FR 59570, Dec. 24, 1975, as amended at 45 FR 57345, Aug. 27, 1980; 65 FR 26022, May 4, 2000]

§ 141.32 [Reserved]
§ 141.33 Record maintenance.

Any owner or operator of a public water system subject to the provisions of this part shall retain on its premises or at a convenient location near its premises the following records:

(a) Records of microbiological analyses and turbidity analyses made pursuant to this part shall be kept for not less than 5 years. Records of chemical analyses made pursuant to this part shall be kept for not less than 10 years. Actual laboratory reports may be kept, or data may be transferred to tabular summaries, provided that the following information is included:

(1) The date, place, and time of sampling, and the name of the person who collected the sample;

(2) Identification of the sample as to whether it was a routine distribution system sample, check sample, raw or process water sample or other special purpose sample;

(3) Date of analysis;

(4) Laboratory and person responsible for performing analysis;

(5) The analytical technique/method used; and

(6) The results of the analysis.

(b) Records of action taken by the system to correct violations of primary drinking water regulations shall be kept for a period not less than 3 years after the last action taken with respect to the particular violation involved.

(c) Copies of any written reports, summaries or communications relating to sanitary surveys of the system conducted by the system itself, by a private consultant, or by any local, State or Federal agency, shall be kept for a period not less than 10 years after completion of the sanitary survey involved.

(d) Records concerning a variance or exemption granted to the system shall be kept for a period ending not less than 5 years following the expiration of such variance or exemption.

(e) Copies of public notices issued pursuant to subpart Q of this part and certifications made to the primacy agency pursuant to § 141.31 must be kept for three years after issuance.

(f) Copies of monitoring plans developed pursuant to this part shall be kept for the same period of time as the records of analyses taken under the plan are required to be kept under paragraph (a) of this section, except as specified elsewhere in this part.

[40 FR 59570, Dec. 24, 1975, as amended at 65 FR 26022, May 4, 2000; 71 FR 478, Jan. 4, 2006]

§ 141.34 [Reserved]
§ 141.35 Reporting for unregulated contaminant monitoring results.

(a) General applicability. This section applies to any owner or operator of a public water system (PWS) required to monitor for unregulated contaminants under § 141.40(a); such owner or operator is referred to as “you.” This section specifies the information that must be reported to EPA prior to the commencement of monitoring and describes the process for reporting monitoring results to EPA. For the purposes of this section, PWS “population served” is the retail population served directly by the PWS as reported to the Federal Safe Drinking Water Information System (SDWIS/Fed); wholesale or consecutive populations are not included. For purposes of this section, the term “finished” means water that is introduced into the distribution system of a PWS and is intended for distribution and consumption without further treatment, except the treatment necessary to maintain water quality in the distribution system (e.g., booster disinfection, addition of corrosion control chemicals). For purposes of this section, the term “State” refers to the State or Tribal government entity that has jurisdiction over your PWS even if that government does not have primary enforcement responsibility for PWSs under the Safe Drinking Water Act. For purposes of this section, the term “PWS Official” refers to the person at your PWS who is able to function as the official spokesperson for the system's Unregulated Contaminant Monitoring Regulation (UCMR) activities; and the term “PWS Technical Contact” refers to the person at your PWS who is responsible for the technical aspects of your UCMR activities, such as details concerning sampling and reporting.

(b) Reporting by all systems. You must meet the reporting requirements of this paragraph if you meet the applicability criteria in § 141.40(a)(1) and (2).

(1) Where to submit UCMR reporting requirement information. Some of your reporting requirements are to be fulfilled electronically and others by mail. Information that must be submitted using EPA's electronic data reporting system must be submitted through: https://www.epa.gov/dwucmr. Documentation that is required to be mailed can be submitted either: To UCMR Sampling Coordinator, USEPA, Technical Support Center, 26 West Martin Luther King Drive (MS 140), Cincinnati, OH 45268; or by email at UCMR_:. In addition, you must notify the public of the availability of unregulated contaminant monitoring data as provided in subpart Q (Public Notification) of this part (40 CFR 141.207). Community Water Systems that detect unregulated contaminants under this monitoring must also address such detections as part of their Consumer Confidence Reports, as provided in subpart O of this part (40 CFR 141.151).

(2) Contacting EPA if your system does not meet applicability criteria or has a status change. If you have received a letter from EPA or your State concerning your required monitoring and your system does not meet the applicability criteria for UCMR established in § 141.40(a)(1) or (2), or if a change occurs at your system that may affect your requirements under UCMR as defined in § 141.40(a)(3) through (5), you must mail or email a letter to EPA, as specified in paragraph (b)(1) of this section. The letter must be from your PWS Official and must include your PWS Identification (PWSID) Code along with an explanation as to why the UCMR requirements are not applicable to your PWS, or have changed for your PWS, along with the appropriate contact information. EPA will make an applicability determination based on your letter and in consultation with the State when necessary. You are subject to UCMR requirements unless and until you receive a letter from EPA agreeing that you do not meet the applicability criteria.

(c) Reporting by large systems. If you serve a population of more than 10,000 people, and meet the applicability criteria in § 141.40(a)(2)(i), you must meet the reporting requirements in paragraphs (c)(1) through (8) of this section.

(1) Contact and zip code information. You must provide contact information by December 31, 2017, and provide updates within 30 days if this information changes. The contact information must be submitted using EPA's electronic data reporting system, as specified in paragraph (b)(1) of this section, and include the name, affiliation, mailing address, phone number, and email address for your PWS Technical Contact and your PWS Official. In addition, as a one-time reporting requirement, you must report the U.S. Postal Service Zip Code(s) for all areas being served water by your PWS.

(2) Sampling location and inventory information. You must provide your sampling location(s) and inventory information by December 31, 2017, using EPA's electronic data reporting system. You must submit, verify or update the following information for each sampling location, or for each approved representative sampling location (as specified in paragraph (c)(3) of this section regarding representative sampling locations): PWSID Code; PWS Name; PWS Facility Identification Code; PWS Facility Name; PWS Facility Type; Water Source Type; Sampling Point Identification Code; Sampling Point Name; and Sampling Point Type Code; (as defined in Table 1 of paragraph (e) of this section). If this information changes, you must report updates, including new sources and sampling locations that are put in use before or during the PWS' UCMR sampling period, to EPA's electronic data reporting system within 30 days of the change.

(3) Proposed ground water representative sampling locations. Some systems that use ground water as a source and have multiple entry points to the distribution system (EPTDSs) may propose monitoring at representative entry point(s), rather than monitor at every EPTDS, as follows:

(i) Qualifications. Large PWSs that have EPA- or State-approved alternate EPTDS sampling locations from a previous UCMR cycle, or as provided for under § 141.23(a)(1), § 141.24(f)(1), or § 141.24(h)(1), may submit a copy of documentation from their State or EPA that approves their alternative sampling plan for EPTDSs. PWSs that do not have an approved alternative EPTDS sampling plan may submit a proposal to sample at representative EPTDS(s) rather than at each individual EPTDS if: They use ground water as a source; all of their well sources have either the same treatment or no treatment; and they have multiple EPTDSs from the same source, such as an aquifer. You must submit a copy of the existing alternate EPTDS sampling plan or your representative well proposal, as appropriate, April 19, 2017, as specified in paragraph (b)(1) of this section.

(ii) Demonstration. If you are submitting a proposal to sample at representative EPTDS(s) rather than at each individual EPTDS, you must demonstrate that any EPTDS that you select as representative of the ground water you supply from multiple wells is associated with a well that draws from the same aquifer as the wells it will represent. The proposed well must be representative of the highest annual volume producing and most consistently active wells in the representative array. If that representative well is not in use at the scheduled sampling time, you must select and sample an alternative representative well. You must submit the following information for each proposed representative sampling location: PWSID Code; PWS Name; PWS Facility Identification Code; PWS Facility Name; PWS Facility Type; Sampling Point Identification Code; and Sampling Point Name (as defined in Table 1, paragraph (e) of this section). You must also include documentation to support your proposal that the specified wells are representative of other wells. This documentation can include system-maintained well logs or construction drawings indicating that the representative well(s) is/are at a representative depth, and details of well casings and grouting; data demonstrating relative homogeneity of water quality constituents (e.g., pH, dissolved oxygen, conductivity, iron, manganese) in samples drawn from each well; and data showing that your wells are located in a limited geographic area (e.g., all wells within a 0.5 mile radius) and/or, if available, the hydrogeologic data indicating the time of travel separating the representative well from each of the individual wells it represents (e.g., all wells within a five-year time of travel delineation). Your proposal must be sent in writing to EPA, as specified in paragraph (b)(1) of this section. You must also provide a copy of this information to the State, unless otherwise directed by the State. Information about the actual or potential occurrence or non-occurrence of contaminants in an individual well, or a well's vulnerability to contamination, must not be used as a basis for selecting a representative well.

(iii) Approval. EPA or the State (as specified in the Partnership Agreement reached between the State and EPA) will review your proposal, coordinate any necessary changes with you, and approve the final list of EPTDSs where you will be required to monitor. Your plan will not be final until you receive written approval from EPA or the State.

(4) Contacting EPA if your PWS has not been notified of requirements. If you believe you are subject to UCMR requirements, as defined in § 141.40(a)(1) and (2)(i), and you have not been notified by either EPA or your State by April 19, 2017, you must send a letter to EPA, as specified in paragraph (b)(1) of this section. The letter must be from your PWS Official and must include an explanation as to why the UCMR requirements are applicable to your system along with the appropriate contact information. A copy of the letter must also be submitted to the State, as directed by the State. EPA will make an applicability determination based on your letter, and in consultation with the State when necessary, and will notify you regarding your applicability status and required sampling schedule. However, if your PWS meets the applicability criteria specified in § 141.40(a)(2)(i), you are subject to the UCMR monitoring and reporting requirements, regardless of whether you have been notified by the State or EPA.

(5) Notifying EPA if your PWS cannot sample according to schedule -

(i) General rescheduling notification requirements. Large systems may change their monitoring schedules up to December 31, 2017, using EPA's electronic data reporting system, as specified in paragraph (b)(1) of this section. After this date has passed, if your PWS cannot sample according to your assigned sampling schedule (e.g., because of budget constraints, or if a sampling location will be closed during the scheduled month of monitoring), you must mail or email a letter to EPA, as specified in paragraph (b)(1) of this section, prior to the scheduled sampling date. You must include an explanation of why the samples cannot be taken according to the assigned schedule, and you must provide the alternative schedule you are requesting. You must not reschedule monitoring specifically to avoid sample collection during a suspected vulnerable period. You are subject to your assigned UCMR sampling schedule or the schedule that you revised on or before December 31, 2017, unless and until you receive a letter from EPA specifying a new schedule.

(ii) Exceptions to the rescheduling notification requirements. For ground water sampling, if the second round of sampling will be completed five to seven months after the first sampling event, as specified in Table 2 of § 141.40(a)(4)(i)(B), no notification to EPA is required. If any ground water sampling location will be non-operational for more than one month before and one month after the month in which the second sampling event is scheduled (i.e., it is not possible for you to sample within the five to seven month window), you must notify EPA, as specified in paragraph (b)(1) of this section, explaining why the schedule cannot be met. You must comply with any modified schedule provided by EPA.

(6) Reporting monitoring results. For UCMR samples, you must report all data elements specified in Table 1 of paragraph (e) of this section, using EPA's electronic data reporting system. You also must report any changes, relative to what is currently posted, made to data elements 1 through 9 to EPA in writing, explaining the nature and purpose of the proposed change, as specified in paragraph (b)(1) of this section.

(i) Electronic reporting system. You are responsible for ensuring that the laboratory conducting the analysis of your unregulated contaminant monitoring samples (your laboratory) posts the analytical results to EPA's electronic reporting system. You are also responsible for reviewing, approving, and submitting those results to EPA.

(ii) Reporting schedule. You must ensure that your laboratory posts the data to EPA's electronic data reporting system within 120 days from the sample collection date (sample collection must occur as specified in § 141.40(a)(4)). You have 60 days from when the laboratory posts the data in EPA's electronic data reporting system to review, approve, and submit the data to the State and EPA, at the Web address specified in paragraph (b)(1) of this section. If you do not electronically approve and submit the laboratory data to EPA within 60 days of the laboratory's posting data to EPA's electronic reporting system, the data will be considered approved by you and available for State and EPA review.

(7) Only one set of results accepted. If you report more than one set of valid results for the same sampling location and the same sampling event (for example, because you have had more than one laboratory analyze replicate samples collected under § 141.40(a)(5), or because you have collected multiple samples during a single monitoring event at the same sampling location), EPA will use the highest of the reported values as the official result.

(8) No reporting of previously collected data. You cannot report previously collected data to meet the testing and reporting requirements for the contaminants listed in § 141.40(a)(3). All analyses must be performed by laboratories approved by EPA to perform UCMR analyses using the analytical methods specified in Table 1 of § 141.40(a)(3) and using samples collected according to § 141.40(a)(4). Such requirements preclude the possibility of “grandfathering” previously collected data.

(d) Reporting by small systems. If you serve a population of 10,000 or fewer people, and you are notified that you have been selected for UCMR monitoring, your reporting requirements will be specified within the materials that EPA sends you, including a request for contact information, and a request for information associated with the sampling kit.

(1) Contact and zip code information. EPA will send you a notice requesting contact information for key individuals at your system, including name, affiliation, mailing address, phone number and email address. These individuals include your PWS Technical Contact and your PWS Official. You are required to provide this contact information within 90 days of receiving the notice from EPA as specified in paragraph (b)(1) of this section. If this contact information changes, you also must provide updates within 30 days of the change, as specified in paragraph (b)(1) of this section. In addition, as a one-time reporting requirement, you must report the U.S. Postal Service Zip Code(s) for all areas being served water by your PWS.

(2) Reporting sampling information. You must provide your sampling location(s) by December 31, 2017, using EPA's electronic data reporting system, as specified in paragraph (b)(1) of this section. If this information changes, you must report updates, including new sources and sampling locations that are put in use before or during the PWS' UCMR sampling period, to EPA's electronic data reporting system within 30 days of the change, as specified in paragraph (b)(1) of this section. You must record all data elements listed in Table 1 of paragraph (e) of this section on each sample form and sample bottle, as appropriate, provided to you by the UCMR Sampling Coordinator. You must send this information as specified in the instructions of your sampling kit, which will include the due date and return address. You must report any changes made in data elements 1 through 9 by emailing an explanation of the nature and purpose of the proposed change to EPA, as specified in paragraph (b)(1) of this section.

(e) Data elements. Table 1 defines the data elements that must be provided for UCMR monitoring.

Table 1 - Unregulated Contaminant Monitoring Reporting Requirements

Data element Definition
1. Public Water System Identification (PWSID) Code The code used to identify each PWS. The code begins with the standard 2-character postal State abbreviation or Region code; the remaining 7 numbers are unique to each PWS in the State. The same identification code must be used to represent the PWS identification for all current and future UCMR monitoring.
2. Public Water System Name Unique name, assigned once by the PWS.
3. Public Water System Facility Identification Code An identification code established by the State or, at the State's discretion, by the PWS, following the format of a 5-digit number unique within each PWS for each applicable facility (i.e., for each source of water, treatment plant, distribution system, or any other facility associated with water treatment or delivery). The same identification code must be used to represent the facility for all current and future UCMR monitoring.
4. Public Water System Facility Name Unique name, assigned once by the PWS, for every facility ID (e.g., Treatment Plant).
5. Public Water System Facility Type That code that identifies that type of facility as either:
CC = consecutive connection.
DS = distribution system.
IN = source water influent.
SS = sampling station.
TP = treatment plant.
OT = other.
6. Water Source Type The type of source water that supplies a water system facility. Systems must report one of the following codes for each sampling location:
SW = surface water (to be reported for water facilities that are served entirely by a surface water source during the twelve-month period).
GW = ground water (to be reported for water facilities that are served entirely by a ground water source during the twelve-month period).
GU = ground water under the direct influence of surface water (to be reported for water facilities that are served all or in part by ground water under the direct influence of surface water at any time during the twelve-month sampling period), and are not served at all by surface water during this period.
MX = mixed water (to be reported for water facilities that are served by a mix of surface water, ground water and/or ground water under the direct influence of surface water during the twelve-month period).
7. Sampling Point Identification Code An identification code established by the State, or at the State's discretion, by the PWS, that uniquely identifies each sampling point. Each sampling code must be unique within each applicable facility, for each applicable sampling location (i.e., entry point to the distribution system, source water influent or distribution system sample at maximum residence time). The same identification code must be used to represent the sampling location for all current and future UCMR monitoring.
8. Sampling Point Name Unique sample point name, assigned once by the PWS, for every sample point ID (e.g., Entry Point).
9. Sampling Point Type Code A code that identifies the location of the sampling point as either:
SR = source water taken from plant influent; untreated water entering the water treatment plant (i.e., a location prior to any treatment).
EP = entry point to the distribution system.
DS = distribution system sample.
10. Disinfectant Type All of the disinfectants/oxidants that have been added prior to the entry point to the distribution system. Please select all that apply:
PEMB = Permanganate.
HPXB = Hydrogen peroxide.
CLGA = Gaseous chlorine.
CLOF = Offsite Generated Hypochlorite (stored as a liquid form).
CLON = Onsite Generated Hypochlorite.
CAGC = Chloramine (formed with gaseous chlorine).
CAOF = Chloramine (formed with offsite hypochlorite).
CAON = Chloramine (formed with onsite hypochlorite).
CLDB = Chlorine dioxide.
OZON = Ozone.
ULVL = Ultraviolet light.
OTHD = All other types of disinfectant/oxidant.
NODU = No disinfectant/oxidant used.
11. Treatment Information Treatment information associated with the sample point. Please select all that apply:
CON = Conventional (non-softening, consisting of at least coagulation/sedimentation basins and filtration).
SFN = Softening.
RBF = River bank filtration.
PSD = Pre-sedimentation.
INF = In-line filtration.
DFL = Direct filtration.
SSF = Slow sand filtration.
BIO = Biological filtration (operated with an intention of maintaining biological activity within filter).
UTR = Unfiltered treatment for surface water source.
GWD = Groundwater system with disinfection only.
PAC = Application of powder activated carbon.
GAC = Granular activated carbon adsorption (not part of filters in CON, SCO, INF, DFL, or SSF).
AIR = Air stripping (packed towers, diffused gas contactors).
POB = Pre-oxidation with chlorine (applied before coagulation for CON or SFN plants or before filtration for other filtration plants).
MFL = Membrane filtration.
IEX = Ionic exchange.
DAF = Dissolved air floatation.
CWL = Clear well/finished water storage without aeration.
CWA = Clear well/finished water storage with aeration.
ADS = Aeration in distribution system (localized treatment).
OTH = All other types of treatment.
NTU = No treatment used.
DKN = Do not know.
12. Disinfectant Residual Type Disinfectant residual type in the distribution system for each HAA sample.
CL2 = Chlorine (i.e., originating from addition of free chlorine only).
CLO2 = chlorine dioxide.
CLM = Chloramines (originating from with addition of chlorine and ammonia or pre-formed chloramines).
CAC = Chlorine and chloramines (if being mixed from chlorinated and chloroaminated water).
NOD = No disinfectant residual.
13. Sample Collection Date The date the sample is collected, reported as 4-digit year, 2-digit month, and 2-digit day (YYYY/MM/DD).
14. Sample Identification Code An alphanumeric value up to 30 characters assigned by the laboratory to uniquely identify containers, or groups of containers, containing water samples collected at the same sampling location for the same sampling date.
15. Contaminant The unregulated contaminant for which the sample is being analyzed.
16. Analytical Method Code The identification code of the analytical method used.
17. Extraction Batch Identification Code Laboratory assigned extraction batch ID. Must be unique for each extraction batch within the laboratory for each method. For CCC samples report the Analysis Batch Identification Code as the value for this field. For methods without an extraction batch, leave this field null.
18. Extraction Date Date for the start of the extraction batch (YYYY/MM/DD). For methods without an extraction batch, leave this field null.
19. Analysis Batch Identification Code Laboratory assigned analysis batch ID. Must be unique for each analysis batch within the laboratory for each method.
20. Analysis Date Date for the start of the analysis batch (YYYY/MM/DD).
21. Sample Analysis Type The type of sample collected and/or prepared, as well as the fortification level. Permitted values include:
CF = concentration fortified; the concentration of a known contaminant added to a field sample reported with sample analysis types LFSM, LFSMD, LFB, CCC and QCS.
CCC = continuing calibration check; a calibration standard containing the contaminant, the internal standard, and surrogate analyzed to verify the existing calibration for those contaminants.
FS = field sample; sample collected and submitted for analysis under this rule.
IS = internal standard; a standard that measures the relative response of contaminants.
LFB = laboratory fortified blank; an aliquot of reagent water fortified with known quantities of the contaminants and all preservation compounds.
LRB = laboratory reagent blank; an aliquot of reagent water treated exactly as a field sample, including the addition of preservatives, internal standards, and surrogates to determine if interferences are present in the laboratory, reagents, or other equipment.
LFSM = laboratory fortified sample matrix; a UCMR field sample with a known amount of the contaminant of interest and all preservation compounds added.
LFSMD = laboratory fortified sample matrix duplicate; duplicate of the laboratory fortified sample matrix.
QCS = quality control sample; a sample prepared with a source external to the one used for initial calibration and CCC. The QCS is used to check calibration standard integrity.
QHS = quality HAA sample; HAA sample collected and submitted for quality control purposes.
SUR = surrogate standard; a standard that assesses method performance for each extraction.
22. Analytical Results - Sign A value indicating whether the sample analysis result was:
(<) “less than” means the contaminant was not detected, or was detected at a level below the Minimum Reporting Level.
(=) “equal to” means the contaminant was detected at the level reported in “Analytical Result - Measured Value.”
23. Analytical Result - Measured Value The actual numeric value of the analytical results for: Field samples; laboratory fortified matrix samples; laboratory fortified sample matrix duplicates; and concentration fortified.
24. Additional Value Represents the true value or the fortified concentration for spiked samples for QC Sample Analysis Types (CCC, EQC, LFB, LFSM and LFSMD). For Sample Analysis Type FS and LRB and for IS and surrogate QC Contaminants, leave this field null.
25. Laboratory Identification Code The code, assigned by EPA, used to identify each laboratory. The code begins with the standard two-character State postal abbreviation; the remaining five numbers are unique to each laboratory in the State.
26. Sample Event Code A code assigned by the PWS for each sample event. This will associate samples with the PWS monitoring plan to allow EPA to track compliance and completeness. Systems must assign the following codes:
SEC1, SEC2, SEC3, SEC4, SEC5, SEC6, SEC7 and SEC8 - represent samples collected to meet UCMR Assessment Monitoring requirements for cyanotoxins; where “SEC1” represents the first sampling period, “SEC2” the second period and so forth, for all eight sampling events.
SEA1, SEA2, SEA3 and SEA4 - represent samples collected to meet UCMR Assessment Monitoring requirements for the additional contaminants; where “SEA1” and “SEA2” represent the first and second sampling period for all water types; and “SEA3” and “SEA4” represent the third and fourth sampling period for SW and GU sources only.
27. Bloom Occurrence A yes or no answer provided by the PWS for each cyanotoxin sample event.
Question: Preceding the finished water sample collection, did you observe an algal bloom in your source waters near the intake?
YES = if yes, select all the YESs that apply:
YD = yes, on the day the UCMR cyanotoxin sample was collected.
YW = yes, between the day the sample was taken and the past week.
YM = yes, between the past week and past month.
YY = yes, between the past month and past year.
YP = yes, prior to the past year.
NO = have never seen a bloom.
28. Cyanotoxin Occurrence A yes or no answer provided by the PWS for each cyanotoxin sample event.
Question: Preceding the finished water sample collection, were cyanotoxins ever detected in your source waters near the intake and prior to any treatment (based on sampling by you or another party)?
YES = if yes, select all the YESs that apply:
YD = yes, on the day the UCMR cyanotoxin sample was collected.
YW = yes, between the day the sample was taken and the past week.
YM = yes, between the past week and past month.
YY = yes, between the past month and past year.
YP = yes, prior to the past year.
NO = have never detected cyanotoxins in source water.
NS = unaware of any source water cyanotoxin sampling.
Select all that apply (i.e., all that were detected) if you answered YES to detecting cyanotoxins in source water:
MIC = Microcystins.
CYL = Cylindrospermopsin.
ANA = Anatoxin-A.
SAX = Saxitoxins.
OTH = Other.
DK = do not know.
29. Indicator of Possible Bloom - Treatment A yes or no answer provided by the PWS for each cyanotoxin sample event.
Question: Preceding the finished water sample collection, did you notice any changes in your treatment system operation and/or treated water quality that may indicate a bloom in the source water?
YES = if yes, select all that apply:
DFR = Decrease in filter runtimes.
ITF = Increase in turbidity in filtered water.
ICD = Need for increased coagulant dose.
TOI = Increase in taste and odor issues in finished water.
IOD = Need for increase in oxidant/disinfectant dose.
IDB = Increase in TTHM/HAA5 in finished water.
OTH = Describe other changes.
NO = no changes.
30. Indicator of Possible Bloom - Source Water Quality Parameters A yes or no answer provided by the PWS for each cyanotoxin sample event.
Question: Preceding the finished water sample collection, did you observe any notable changes in source water quality parameters (if measured)?
YES = if yes, select all that apply to the source water:
ITP = Increase in water temperature.
ITU = Increase in turbidity.
IAL = Increase in alkalinity.
ITO = Increase in total organic carbon.
ICD = Increase in chlorine demand.
IPH = Increase in pH.
ICA = Increase in chlorophyll a.
IPY = Increase in phycocyanin.
INU = Increase in nutrients (example: nitrogen or phosphorus).
OTH = Describe other changes.
NO = no changes observed.

[72 FR 389, Jan. 4, 2007, as amended at 77 FR 26096, May 2, 2012; 81 FR 92684, Dec. 20, 2016]

Subpart E - Special Regulations, Including Monitoring
§ 141.40 Monitoring requirements for unregulated contaminants.

(a) General applicability. This section specifies the monitoring and quality control requirements that must be followed if you own or operate a public water system (PWS) that is subject to the Unregulated Contaminant Monitoring Regulation (UCMR), as specified in paragraphs (a)(1) and (2) of this section. In addition, this section specifies the UCMR requirements for State and Tribal participation. For the purposes of this section, PWS “population served,” “State,” ” PWS Official,” “PWS Technical Contact,” and “finished water” apply as defined in § 141.35(a). The determination of whether a PWS is required to monitor under this rule is based on the type of system (e.g., community water system, non-transient non-community water system, etc.), and its retail population, as indicated by SDWIS/Fed on December 31, 2015.

(1) Applicability to transient non-community systems. If you own or operate a transient non-community water system, you are not subject to monitoring requirements in this section.

(2) Applicability to community water systems and non-transient non-community water systems -

(i) Large systems. If you own or operate a retail PWS (other than a transient non-community system) that serves more than 10,000 people, you must monitor according to the specifications in this paragraph (a)(2)(i). If you believe that your applicability status is different than EPA has specified in the notification letter that you received, or if you are subject to UCMR requirements and you have not been notified by either EPA or your State, you must report to EPA, as specified in § 141.35(b)(2) or (c)(4).

(A) Assessment monitoring. You must monitor for the contaminants on List 1, per Table 1, UCMR Contaminant List, in paragraph (a)(3) of this section. If you serve a retail population of more than 10,000 people, you are required to perform this monitoring regardless of whether you have been notified by the State or EPA.

(B) Screening Survey. You must monitor for the unregulated contaminants on List 2 (Screening Survey) of Table 1, as specified in paragraph (a)(3) of this section, if your system serves 10,001 to 100,000 people and you are notified by EPA or your State that you are part of the State Monitoring Plan for Screening Survey testing. If your system serves more than 100,000 people, you are required to conduct this Screening Survey testing regardless of whether you have been notified by the State or EPA.

(C) Pre-Screen Testing. You must monitor for the unregulated contaminants on List 3 of Table 1, in paragraph (a)(3) of this section, if notified by your State or EPA that you are part of the Pre-Screen Testing.

(ii) Small systems. Small PWSs, as defined in this paragraph, will not be selected to monitor for any more than one of the three monitoring lists provided in Table 1, UCMR Contaminant List, in paragraph (a)(3) of this section. EPA will provide sample containers, provide pre-paid air bills for shipping the sampling materials, conduct the laboratory analysis, and report and review monitoring results for all small systems selected to conduct monitoring under paragraphs (a)(2)(ii)(A) through (C) of this section. If you own or operate a PWS that serves 10,000 or fewer people you must monitor as follows:

(A) Assessment monitoring. You must monitor for the contaminants on List 1 per Table 1, in paragraph (a)(3) of this section, if you are notified by your State or EPA that you are part of the State Monitoring Plan for Assessment Monitoring.

(B) Screening Survey. You must monitor for the unregulated contaminants on List 2 of Table 1, in paragraph (a)(3) of this section, if notified by your State or EPA that you are part of the State Monitoring Plan for the Screening Survey.

(C) Pre-screen testing. You must monitor for the contaminants on List 3 of Table 1, in paragraph (a)(3) of this section if you are notified by your State or EPA that you are part of the State Monitoring Plan for Pre-Screen Testing.

(3) Analytes to be monitored. Lists 1, 2, and 3 contaminants are provided in the following table:

Table 1 - UCMR Contaminant List

1 - Contaminant 2 - CAS
Registry No.
3 - Analytical
methodsa
4 - Minimum
reporting levelb
5 - Sampling
locationc
6 - Period during
which monitoring
to be completed
List 1: Assessment Monitoring Cyanotoxin Chemical Contaminants
“total microcystin” N/A EPA 546 0.3 µg/L EPTDS 3/1/2018-11/30/2020.
anatoxin-a 64285-06-9 EPA 545 0.03 µg/L EPTDS 3/1/2018-11/30/2020.
cylindrospermopsin 143545-90-8 EPA 545 0.09 µg/L EPTDS 3/1/2018-11/30/2020.
microcystin-LA 96180-79-9 EPA 544 0.008 µg/L EPTDS 3/1/2018-11/30/2020.
microcystin-LF 154037-70-4 EPA 544 0.006 µg/L EPTDS 3/1/2018-11/30/2020.
microcystin-LR 101043-37-2 EPA 544 0.02 µg/L EPTDS 3/1/2018-11/30/2020.
microcystin-LY 123304-10-9 EPA 544 0.009 µg/L EPTDS 3/1/2018-11/30/2020.
microcystin-RR 111755-37-4 EPA 544 0.006 µg/L EPTDS 3/1/2018-11/30/2020.
microcystin-YR 101064-48-6 EPA 544 0.02 µg/L EPTDS 3/1/2018-11/30/2020.
nodularin 118399-22-7 EPA 544 0.005 µg/L EPTDS 3/1/2018-11/30/2020.
List 1: Assessment Monitoring Additional Chemical Contaminants
Metals
germanium 7440-56-4 EPA 200.8, ASTM D5673-10, SM 3125 0.3 µg/L EPTDS 1/1/2018-12/31/2020.
manganese 7439-96-5 EPA 200.8, ASTM D5673-10, SM 3125 0.4 µg/L EPTDS 1/1/2018-12/31/2020.
Pesticides and a Pesticide Manufacturing Byproduct
alpha-hexachlorocyclohexane 319-84-6 EPA 525.3 0.01 µg/L EPTDS 1/1/2018-12/31/2020.
chlorpyrifos 2921-88-2 EPA 525.3 0.03 µg/L EPTDS 1/1/2018-12/31/2020.
dimethipin 55290-64-7 EPA 525.3 0.2 µg/L EPTDS 1/1/2018-12/31/2020.
ethoprop 13194-48-4 EPA 525.3 0.03 µg/L EPTDS 1/1/2018-12/31/2020.
oxyfluorfen 42874-03-3 EPA 525.3 0.05 µg/L EPTDS 1/1/2018-12/31/2020.
profenofos 41198-08-7 EPA 525.3 0.3 µg/L EPTDS 1/1/2018-12/31/2020.
tebuconazole 107534-96-3 EPA 525.3 0.2 µg/L EPTDS 1/1/2018-12/31/2020.
total permethrin (cis- & trans-) 52645-53-1 EPA 525.3 0.04 µg/L EPTDS 1/1/2018-12/31/2020.
tribufos 78-48-8 EPA 525.3 0.07 µg/L EPTDS 1/1/2018-12/31/2020.
Brominated Haloacetic Acid (HAA) Groups d e
HAA5 N/A EPA 552.3 or EPA 557 N/A D/DBPR HAA location 1/1/2018-12/31/2020.
HAA6Br N/A EPA 552.3 or EPA 557 N/A D/DBPR HAA location 1/1/2018-12/31/2020.
HAA9 N/A EPA 552.3 or EPA 557 N/A D/DBPR HAA location 1/1/2018-12/31/2020.
Alcohols
1-butanol 71-36-3 EPA 541 2.0 µg/L EPTDS 1/1/2018-12/31/2020.
2-methoxyethanol 109-86-4 EPA 541 0.4 µg/L EPTDS 1/1/2018-12/31/2020.
2-propen-1-ol 107-18-6 EPA 541 0.5 µg/L EPTDS 1/1/2018-12/31/2020.
Other Semivolatile Chemicals
butylated hydroxanisole 25013-16-5 EPA 530 0.03 µg/L EPTDS 1/1/2018-12/31/2020.
o-toluidine 95-53-4 EPA 530 0.007 µg/L EPTDS 1/1/2018-12/31/2020.
quinoline 91-22-5 EPA 530 0.02 µg/L EPTDS 1/1/2018-12/31/2020.
List 2: Screening Survey
Reserved Reserved Reserved Reserved Reserved Reserved.
List 3: Pre-Screen Testing
Reserved Reserved Reserved Reserved Reserved Reserved.

(4) Sampling requirements -

(i) Large systems. If you serve more than 10,000 people and meet the UCMR applicability criteria specified in paragraph (a)(2)(i) of this section, you must comply with the requirements specified in paragraphs (a)(4)(i)(A) through (I) of this section. Your samples must be collected according to the schedule that you are assigned by EPA or your State, or the schedule that you revised using EPA's electronic data reporting system on or before December 31, 2017. Your schedule must follow both the timing and frequency of monitoring specified in Tables 1 and 2 of this section.

(A) Monitoring period. You must collect the samples in one continuous 12-month period for List 1 Assessment Monitoring, and, if applicable, for List 2 Screening Survey, or List 3 Pre-Screen Testing, during the time frame indicated in column 6 of Table 1, in paragraph (a)(3) of this section. EPA or your State will specify the month(s) and year(s) in which your monitoring must occur. As specified in § 141.35(c)(5), you must contact EPA if you believe you cannot conduct monitoring according to your schedule.

(B) Frequency. You must collect the samples within the timeframe and according to the frequency specified by contaminant type and water source type for each sampling location, as specified in Table 2, in this paragraph. For the second or subsequent round of sampling, if a sample location is non-operational for more than one month before and one month after the scheduled sampling month (i.e., it is not possible for you to sample within the window specified in Table 2, in this paragraph), you must notify EPA as specified in § 141.35(c)(5) to reschedule your sampling.

Table 2 - Monitoring Frequency by Contaminant and Water Source Types

Contaminant type Water source type Timeframe Frequency1
List 1 Cyanotoxins Chemicals Surface water or Ground water under the direct influence of surface water (GWUDI) March-November You must monitor twice a month for four consecutive months (total of eight sampling events). Sample events must occur two weeks apart.
List 1 Contaminants - Additional Chemicals Surface water or GWUDI 12 months You must monitor for four consecutive quarters. Sample events must occur three months apart. (Example: If first monitoring is in January, the second monitoring must occur any time in April, the third any time in July and the fourth any time in October).
Ground water 12 months You must monitor twice in a consecutive 12-month period. Sample events must occur 5-7 months apart. (Example: If the first monitoring event is in April, the second monitoring event must occur any time in September, October or November).

(C) Location. You must collect samples for each List 1 Assessment Monitoring contaminant, and, if applicable, for each List 2 Screening Survey, or List 3 Pre-Screen Testing contaminant, as specified in Table 1, in paragraph (a)(3) of this section. Samples must be collected at each sample point that is specified in column 5 and footnote c of Table 1, in paragraph (a)(3) of this section. PWSs conducting List 1 monitoring for the brominated HAA groups must collect TOC and bromide samples as specified in footnote d of Table 1, in paragraph (a)(3) of this section. If you are a GW system with multiple EPTDSs, and you request and receive approval from EPA or the State for sampling at representative EPTDS(s), as specified in § 141.35(c)(3), you must collect your samples from the approved representative sampling location(s).

(D) Sampling instructions. For each List 1 Assessment Monitoring contaminant, and, if applicable, for each List 2 Screening Survey, or List 3 Pre-Screen Testing contaminant, you must follow the sampling procedure for the method specified in column 3 of Table 1, in paragraph (a)(3) of this section. In addition, you must not composite (that is, combine, mix, or blend) the samples; you must collect and preserve each sample separately.

(E) Sample collection and shipping time. If you must ship the samples for analysis, you must collect the samples early enough in the day to allow adequate time to send the samples for overnight delivery to the laboratory. You should not collect samples on Friday, Saturday, or Sunday because sampling on these days may not allow samples to be shipped and received at the laboratory at the required temperature, unless you have made special arrangements with your laboratory to receive the samples.

(F) Analytical methods. For each contaminant, you must use the respective analytical methods for List 1, and, if applicable, for List 2, or List 3 that are specified in column 3 of Table 1, in paragraph (a)(3) of this section; report values at or above the minimum reporting levels for List 1, and, if applicable, for List 2 Screening Survey, or List 3 Pre-Screen Testing, that are specified in column 4 of Table 1, in paragraph (a)(3) of this section; and conduct the quality control procedures specified in paragraph (a)(5) of this section.

(G) Laboratory errors or sampling deviations. If the laboratory data do not meet the required QC criteria, as specified in paragraph (a)(5) of this section, or you do not follow the required sampling procedures, as specified in paragraphs (a)(4) of this section, you must resample within 30 days of being informed or becoming aware of these facts. This resampling is not for the purpose of confirming previous results, but to correct the sampling or laboratory error. All systems must report the results obtained from the first sampling for each sampling period, except for cases of sampling or laboratory errors. For the purposes of this rule, no samples are to be recollected for the purposes of confirming the results observed in a previous sampling.

(H) Analysis. For the List 1 contaminants, and, if applicable, List 2 Screening Survey, or List 3 Pre-Screen Testing contaminants, identified in Table 1, paragraph (a)(3) of this section, you must arrange for testing by a laboratory that has been approved by EPA according to requirements in paragraph (a)(5)(ii) of this section.

(I) Review and reporting of results. After you have received the laboratory results, you must review, approve, and submit the system information, and sample collection data and test results. You must report the results as provided in § 141.35(c)(6).

(ii) Small systems. If you serve 10,000 or fewer people and are notified that you are part of the State Monitoring Plan for Assessment Monitoring, Screening Survey or Pre-Screen monitoring, you must comply with the requirements specified in paragraphs (a)(4)(ii)(A) through (H) of this section. If EPA or the State informs you that they will be collecting your UCMR samples, you must assist them in identifying the appropriate sampling locations and in collecting the samples.

(A) Monitoring period and frequency. You must collect samples at the times specified for you by the State or EPA. Your schedule must follow both the timing of monitoring specified in Table 1, List 1, and, if applicable, List 2, or List 3, and the frequency of monitoring in Table 2 of this section.

(B) Location. You must collect samples at the locations specified for you by the State or EPA.

(C) Sample kits. You must store and maintain the sample collection kits sent to you by the UCMR Sampling Coordinator in accordance with the kit's instructions. The sample kit will include all necessary containers, packing materials and cold packs, instructions for collecting the sample and sample treatment (such as dechlorination or preservation), report forms for each sample, contact name and telephone number for the laboratory, and a prepaid return shipping docket and return address label. If any of the materials listed in the kit's instructions are not included in the kit or arrive damaged, you must notify the UCMR Sampling Coordinator who sent you the sample collection kits.

(D) Sampling instructions. You must comply with the instructions sent to you by the State or EPA concerning the use of containers, collection (how to fill the sample bottle), dechlorination and/or preservation, and sealing and preparation of sample and shipping containers for shipment. You must not composite (that is, combine, mix, or blend) the samples. You also must collect, preserve, and test each sample separately. You must also comply with the instructions sent to you by the UCMR Sampling Coordinator concerning the handling of sample containers for specific contaminants.

(E) Sampling deviations. If you do not collect a sample according to the instructions provided to you for a listed contaminant, you must report the deviation within 7 days of the scheduled monitoring on the sample reporting form, as specified in § 141.35(d)(2). You must resample following instructions that you will be sent from the UCMR Sampling Coordinator or State. A copy of the form must be sent to the laboratory with the recollected samples, and to the UCMR Sampling Coordinator.

(F) [Reserved]

(G) Sampling forms. You must completely fill out each of the sampling forms and bottles sent to you by the UCMR Sampling Coordinator, including data elements listed in § 141.35(e) for each sample, as specified in § 141.35(d)(2). You must sign and date the sampling forms.

(H) Sample collection and shipping. You must collect the samples early enough in the day to allow adequate time to send the samples for overnight delivery to the laboratory. You should not collect samples on Friday, Saturday, or Sunday because sampling on these days may not allow samples to be shipped and received at the laboratory at the required temperature unless you have made special arrangements with EPA for the laboratory to receive the samples. Once you have collected the samples and completely filled in the sampling forms, you must send the samples and the sampling forms to the laboratory designated on the air bill.

(iii) Phased sample analysis for microcystins. You must collect the three required samples (one each for EPA Methods 544, 545 and 546 (ELISA) at the EPTDS) for each sampling event, but not all samples may need to be analyzed. If the Method 546 ELISA result is less than 0.3 µg/L, report that result and do not analyze the EPA Method 544 sample for that sample event. If the Method 546 ELISA result is greater than or equal to 0.3 µg/L, report the value and analyze the other microcystin sample using EPA Method 544. You must analyze the EPA Method 545 sample for each sample event for Cylindrospermopsin and anatoxin-a only.

(5) Quality control requirements. If your system serves more than 10,000 people, you must ensure that the quality control requirements listed below are met during your sampling procedures and by the laboratory conducting your analyses. You must also ensure that all method quality control procedures and all UCMR quality control procedures are followed.

(i) Sample collection/preservation. You must follow the sample collection and preservation requirements for the specified method for each of the contaminants in Table 1, in paragraph (a)(3) of this section. These requirements specify sample containers, collection, dechlorination, preservation, storage, sample holding time, and extract storage and/or holding time that you must assure that the laboratory follow.

(ii) Laboratory approval for Lists 1, List 2 and List 3. To be approved to conduct UCMR testing, the laboratory must be certified under § 141.28 for one or more compliance analyses; demonstrate for each analytical method it plans to use for UCMR testing that it can meet the Initial Demonstration of Capability (IDC) requirements detailed in the analytical methods specified in column 3 of Table 1, in paragraph (a)(3) of this section; and successfully participate in the UCMR Proficiency Testing (PT) Program administered by EPA for each analytical method it plans to use for UCMR testing. UCMR laboratory approval decisions will be granted on an individual method basis for the methods listed in column 3 of Table 1 in paragraph (a)(3) of this section for List 1, List 2, and List 3 contaminants. Laboratory approval is contingent upon the capability of the laboratory to post monitoring data to the EPA electronic data reporting system. To participate in the UCMR Laboratory Approval Program, the laboratory must complete and submit the necessary registration forms by February 21, 2017, and necessary application material April 19, 2017. Correspondence must be addressed to: UCMR Laboratory Approval Coordinator, USEPA, Technical Support Center, 26 West Martin Luther King Drive, (MS 140), Cincinnati, OH 45268; or emailed to EPA at: .

(iii) Minimum Reporting Level. The MRL is an estimate of the quantitation limit. Assuming good instrumentation and experienced analysts, an MRL is achievable, with 95% confidence, by 75% of laboratories nationwide.

(A) Validation of laboratory performance. Your laboratory must be capable of quantifying each contaminant listed in Table 1, at or below the MRL specified in column 4 of Table 1, in paragraph (a)(3) of this section. You must ensure that the laboratory completes and has on file and available for your inspection, records of two distinct procedures. First, your laboratory must have conducted an IDC involving replicate analyses at or below the MRL as described in this paragraph. Second, for each day that UCMR analyses are conducted by your laboratory, a validation of its ability to quantify each contaminant, at or below the MRL specified in column 4 of Table 1, in paragraph (a)(3) of this section, following the procedure listed in paragraph (a)(5)(iii)(B) of this section, must be performed. The procedure for initial validation of laboratory performance at or below the MRL is as follows:

(1) All laboratories performing analysis under UCMR must demonstrate that they are capable of meeting data quality objectives at or below the MRL listed in Table 1, column 4, in paragraph (a)(3) of this section.

(2) The MRL, or any concentration below the MRL, at which performance is being evaluated, must be contained within the range of calibration. The calibration curve regression model and the range of calibration levels that are used in these performance validation steps must be used in all routine sample analyses used to comply with this regulation. Only straight line or quadratic regression models are allowed. The use of either weighted or unweighted models is permitted. The use of cubic regression models is not permitted.

(3) Replicate analyses of at least seven (7) fortified samples in reagent water must be performed at or below the MRL for each analyte, and must be processed through the entire method procedure (i.e., including extraction, where applicable, and with all preservatives).

(4) A prediction interval of results (PIR), which is based on the estimated arithmetic mean of analytical results and the estimated sample standard deviation of measurement results, must be determined by Equation 1:

Where:

t is the Student's t value with df degrees of freedom and confidence level (1-α),

s is the sample standard deviation of n replicate samples fortified at the MRL,

n is the number of replicates.

(5) The values needed to calculate the PIR using Equation 1 are: Number of replicates (n); Student's t value with a two-sided 99% confidence level for n number of replicates; the average (mean) of at least seven replicates; and the sample standard deviation. Factor 1 is referred to as the Half Range PIR (HRPIR).

For a certain number of replicates and for a certain confidence level in Student's t, this factor

is constant, and can be tabulated according to replicate number and confidence level for the Student's t. Table 3 in this paragraph lists the constant factor (C) for replicate sample numbers 7 through 10 with a confidence level of 99% for Student's t.

(6) The HRPIR is calculated by Equation 2:

(7) The PIR is calculated by Equation 3:

Table 3 - The Constant Factor (C) to be Multiplied by the Standard Deviation to Determine the Half Range Interval of the PIR (Student's t 99% Confidence Level)a

Replicates Degrees of freedom Constant factor (C) to be multiplied by the standard
deviation
7 6 3.963
8 7 3.711
9 8 3.536
10 9 3.409

(8) The lower and upper result limits of the PIR must be converted to percent recovery of the concentration being tested. To pass criteria at a certain level, the PIR lower recovery limits cannot be lower than the lower recovery limits of the QC interval (50%), and the PIR upper recovery limits cannot be greater than the upper recovery limits of the QC interval (150%). When either of the PIR recovery limits falls outside of either bound of the QC interval of recovery (higher than 150% or less than 50%), laboratory performance is not validated at the concentration evaluated. If the PIR limits are contained within both bounds of the QC interval, laboratory performance is validated for that analyte.

(B) Quality control requirements for validation of laboratory performance at or below the MRL.

(1) You must ensure that the calibration curve regression model and that the range of calibration levels that are used in these performance validation steps are used in future routine sample analysis. Only straight line or quadratic regression models are allowed. The use of either weighted or unweighted models is permitted. The use of cubic regression models is not permitted.

(2) You must ensure, once your laboratory has performed an IDC as specified in each analytical method (demonstrating that DQOs are met at or below an MRL), that a daily performance check is performed for each analyte and method. A single laboratory blank, fortified at or below the MRL for each analyte, must be processed through the entire method procedure. The measured concentration for each analyte must be converted to a percent recovery, and if the recovery is within 50%-150% (inclusive), the daily performance of the laboratory has been validated. The results for any analyte for which 50%-150% recovery cannot be demonstrated during the daily check are not valid. Laboratories may elect to re-run the daily performance check sample if the performance for any analyte or analytes cannot be validated. If performance is validated for these analytes, the laboratory performance is considered validated. Alternatively, the laboratory may re-calibrate and repeat the performance validation process for all analytes.

(iv) Laboratory fortified sample matrix and laboratory fortified sample matrix duplicate. You must ensure that your laboratory prepares and analyzes the Laboratory Fortified Sample Matrix (LFSM) sample for accuracy and Laboratory Fortified Sample Matrix Duplicate (LFSMD) samples for precision to determine method accuracy and precision for all contaminants in Table 1, in paragraph (a)(3) of this section. LFSM/LFSMD samples must be prepared using a sample collected and analyzed in accordance with UCMR requirements and analyzed at a frequency of 5% (or 1 LFSM/LFSMD set per every 20 samples) or with each sample batch, whichever is more frequent. In addition, the LFSM/LFSMD fortification concentrations must be alternated between a low-level fortification and mid-level fortification approximately 50% of the time. (For example: A set of 40 samples will require preparation and analysis of 2 LFSM/LFSMD paired samples. The first LFSM/LFSMD paired sample set must be fortified at either the low-level or mid-level, and the second LFSM/LFSMD paired sample set must be fortified with the other standard, either the low-level or mid-level, whichever was not used for the initial LFSM/LFSMD paired sample set.) The low-level LFSM/LFSMD fortification concentration must be within ±50% of the MRL for each contaminant (e.g., for an MRL of 1 µg/L the acceptable fortification levels must be between 0.5 µg/L and 1.5 µg/L). The mid-level LFSM/LFSMD fortification concentration must be within ±20% of the mid-level calibration standard for each contaminant, and is to represent, where possible and where the laboratory has data from previously analyzed samples, an approximate average concentration observed in previous analyses of that analyte. There are no UCMR contaminant recovery acceptance criteria specified for LFSM/LFSMD analyses. All LFSM/LFSMD data are to be reported.

(v) Method defined quality control. You must ensure that your laboratory analyzes Laboratory Fortified Blanks and conducts Laboratory Performance Checks, as appropriate to the method's requirements, for those methods listed in Table 1, column 3, in paragraph (a)(3) of this section. Each method specifies acceptance criteria for these QC checks. The following HAA results must be reported using EPA's electronic data reporting system for quality control purposes.

Table 4 - HAA QC Results

1 - Contaminant 2 - CAS
Registry No.
3 - Analytical
methodsa
4 - Minimum
reporting levelb
5 - HAA6Br Group 6 - HAA9 Group 7 - HAA5 Group
Brominated Haloacetic Acid (HAA) Groups
Bromochloroacetic acid (BCAA) 5589-96-8 EPA 552.3 or EPA 557 0.3 µg/L
Bromodichloroacetic acid (BDCAA) 71133-14-7 EPA 552.3 or EPA 557 0.5 µg/L
Chlorodibromoacetic acid (CDBAA) 5278-95-5 EPA 552.3 or EPA 557 0.3 µg/L HAA6Br
Tribromoacetic acid (TBAA) 75-96-7 EPA 552.3 or EPA 557 2.0 µg/L
Monobromoacetic acid (MBAA) 79-08-3 EPA 552.3 or EPA 557 0.3 µg/L
Dibromoacetic acid (DBAA) 631-64-1 EPA 552.3 or EPA 557 0.3 µg/L HAA9
Dichloroacetic acid (DCAA) 79-43-6 EPA 552.3 or EPA 557 0.2 µg/L
Monochloroacetic acid (MCAA) 79-11-8 EPA 552.3 or EPA 557 2.0 µg/L HAA5
Trichloroacetic acid (TCAA) 76-03-9 EPA 552.3 or EPA 557 0.5 µg/L

(vi) Reporting. You must require your laboratory to submit these data electronically to the State and EPA using EPA's electronic data reporting system, accessible at https://www.epa.gov/dwucmr, within 120 days from the sample collection date. You then have 60 days from when the laboratory posts the data to review, approve and submit the data to the State and EPA, via EPA's electronic data reporting system. If you do not electronically approve and submit the laboratory data to EPA within 60 days of the laboratory posting data to EPA's electronic reporting system, the data will be considered approved and available for State and EPA review.

(6) Violation of this rule -

(i) Monitoring violations. Any failure to monitor in accordance with § 141.40(a)(3)-(5) is a monitoring violation.

(ii) Reporting violations. Any failure to report in accordance with § 141.35 is a reporting violation.

(b) Petitions and waivers by States -

(1) Governors' petition for additional contaminants. The Safe Drinking Water Act allows Governors of seven (7) or more States to petition the EPA Administrator to add one or more contaminants to the UCMR Contaminant List in paragraph (a)(3) of this section. The petition must clearly identify the reason(s) for adding the contaminant(s) to the monitoring list, including the potential risk to public health, particularly any information that might be available regarding disproportional risks to the health and safety of children, the expected occurrence documented by any available data, any analytical methods known or proposed to be used to test for the contaminant(s), and any other information that could assist the Administrator in determining which contaminants present the greatest public health concern and should, therefore, be included on the UCMR Contaminant List in paragraph (a)(3) of this section.

(2) State-wide waivers. A State can waive monitoring requirements only with EPA approval and under very limited conditions. Conditions and procedures for obtaining a waiver are as follows:

(i) Application. A State may apply to EPA for a State-wide waiver from the unregulated contaminant monitoring requirements for PWSs serving more than 10,000 people. To apply for such a waiver, the State must submit an application to EPA that includes the following information: The list of contaminants on the UCMR Contaminant List for which a waiver is requested, along with documentation for each contaminant in the request demonstrating that the contaminants or their parent compounds do not occur naturally in the State, and certifying that during the past 15 years they have not been used, applied, stored, disposed of, released, or detected in the source waters or distribution systems in the State.

(ii) Approval. EPA will review State applications and notify the State whether it accepts or rejects the request. The State must receive written approval from EPA before issuing a State-wide waiver.

(c) Incorporation by reference. These standards are incorporated by reference into this section with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. All approved material is available for inspection either electronically at http://www.regulations.gov, in hard copy at the Water Docket, EPA/DC, and from the sources as follows. The Public Reading Room (EPA West, Room 3334, 1301 Constitution Ave. NW., Washington, DC) is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for this Public Reading Room is (202) 566-1744, and the telephone number for the Water Docket is (202) 566-2426. The material is also available for inspection at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call (202) 741-6030 or go to http://www.archives.gov/federal-register/cfr/about.html.

(1) U.S. Environmental Protection Agency, Water Docket, EPA/DC, EPA West, Room 3334, 1301 Constitution Ave. NW., Washington, DC 20004.

(i) Method 200.8 “Determination of Trace Elements in Waters and Wastes by Inductively Coupled Plasma - Mass Spectrometry,” Revision 5.4, EMMC Version, 1994. Available on the Internet at https://www.nemi.gov.

(ii) Method 300.0 “Determination of Inorganic Anions by Ion Chromatography Samples,” Revision 2.1, August 1993. Available on the Internet at https://www.nemi.gov.

(iii) Method 300.1 “Determination of Inorganic Anions in Drinking Water by Ion Chromatography,” Revision 1.0, 1997. Available on the Internet at https://www.epa.gov/dwanalyticalmethods.

(iv) Method 317.0 “Determination of Inorganic Oxyhalide Disinfection By-Products in Drinking Water Using Ion Chromatography with the Addition of a Postcolumn Reagent for Trace Bromate Analysis,” Revision 2.0, July 2001, EPA 815-B-01-001. Available on the Internet at https://www.epa.gov/dwanalyticalmethods.

(v) Method 326.0 “Determination of Inorganic Oxyhalide Disinfection By-Products in Drinking Water Using Ion Chromatography Incorporating the Addition of a Suppressor Acidified Postcolumn Reagent for Trace Bromate Analysis,” Revision 1.0, June 2002, EPA 815-R-03-007. Available on the Internet at https://www.epa.gov/dwanalyticalmethods.

(vi) Method 415.3 “Determination of Total Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water,” Revision 1.1, February 2005, EPA/600/R-05/055. Available on the Internet at https://www.epa.gov/water-research/epa-drinking-water-research-methods.

(vii) Method 415.3 “Determination of Total Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water,” Revision 1.2, September 2009, EPA/600/R-09/122. Available on the Internet at https://www.epa.gov/water-research/epa-drinking-water-research-methods.

(viii) Method 525.3 “Determination of Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS),” Version 1.0, February 2012, EPA/600/R-12/010. Available on the Internet https://www.epa.gov/water-research/epa-drinking-water-research-methods.

(ix) Method 530 “Determination of Select Semivolatile Organic Chemicals in Drinking Water by Solid Phase Extraction and Gas Chromatography/Mass Spectrometry (GC/MS),” Version 1.0, January 2015, EPA/600/R-14/442. Available on the Internet at https://www.epa.gov/water-research/epa-drinking-water-research-methods.

(x) EPA Method 541: “Determination of 1-Butanol, 1,4-Dioxane, 2-Methoxyethanol and 2-Propen-1-ol in Drinking Water by Solid Phase Extraction and Gas Chromatography/Mass Spectrometry,” November 2015, EPA 815-R-15-011. Available on the Internet at https://www.epa.gov/water-research/epa-drinking-water-research-methods.

(xi) Method 544 “Determination of Microcystins and Nodularin in Drinking Water by Solid Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS),” Version 1.0, February 2015, EPA 600-R-14/474. Available on the Internet at https://www.epa.gov/water-research/epa-drinking-water-research-methods.

(xii) EPA Method 545: “Determination of Cylindrospermopsin and Anatoxin-a in Drinking Water by Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS),” April 2015, EPA 815-R-15-009. Available on the Internet at https://www.epa.gov/dwanalyticalmethods.

(xiii) EPA Method 546: “Determination of Total Microcystins and Nodularins in Drinking Water and Ambient Water by Adda Enzyme-Linked Immunosorbent Assay,” August 2016, EPA-815-B-16-011. Available on the Internet at https://www.epa.gov/dwanalyticalmethods.

(xiv) Method 552.3 “Determination of Haloacetic Acids and Dalapon in Drinking Water by Liquid-Liquid Microextraction, Derivatization, and Gas Chromatography with Electron Capture Detection,” Revision 1.0, July 2003, EPA 815-B-03-002. Available on the Internet at https://www.epa.gov/dwanalyticalmethods.

(xv) EPA Method 557: “Determination of Haloacetic Acids, Bromate, and Dalapon in Drinking Water by Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS),” Version 1.0, September 2009, EPA 815-B-09-012. Available on the Internet at https://www.epa.gov/dwanalyticalmethods.

(2) American Public Health Association - Standard Test Method for Elements in Water by Inductively Coupled Plasma-Mass Spectrometry,” approved August 1, 2010. Available for purchase on the Internet at http://www.astm.org/Standards/D5673.htm.

(i) “Standard Methods for the Examination of Water & Wastewater,” 21st edition (2005).

(A) SM 3125 “Metals by Inductively Coupled Plasma/Mass Spectrometry.”

(B) SM 5310B “Total Organic Carbon (TOC): High-Temperature Combustion Method.”

(C) SM 5310C “Total Organic Carbon (TOC): Persulfate-UV or Heated-Persulfate Oxidation Method.”

(D) SM 5310D “Total Organic Carbon (TOC): Wet-Oxidation Method.”

(ii) The following methods are from “Standard Methods Online.,” approved 2000 (unless noted). Available for purchase on the Internet at http://www.standardmethods.org.

(A) SM 3125 “Metals by Inductively Coupled Plasma/Mass Spectrometry” Editorial revisions, 2011 (SM 3125-09).

(B) SM 5310B “Total Organic Carbon: High-Temperature Combustion Method,” (5310B-00).

(C) SM 5310C “Total Organic Carbon: Persulfate-UV or Heated-Persulfate Oxidation Method,” (5310C-00).

(D) SM 5310D “Total Organic Carbon: Wet-Oxidation Method,” (5310D-00).

(3) ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959.

(i) ASTM D5673-10 “Standard Test Method for Elements in Water by Inductively Coupled Plasma-Mass Spectrometry,” approved August 1, 2010. Available for purchase on the Internet at http://www.astm.org/Standards/D5673.htm.

(ii) ASTM D6581-12 “Standard Test Methods for Bromate, Bromide, Chlorate, and Chlorite in Drinking Water by Suppressed Ion Chromatography,” approved March 1, 2012. Available for purchase on the Internet at http://www.astm.org/Standards/D6581.htm.

[72 FR 393, Jan. 4, 2007; 72 FR 3916, Jan. 26, 2007, as amended at 77 FR 26098, May 2, 2012; 81 FR 92688, Dec. 20, 2016]

§ 141.41 Special monitoring for sodium.

(a) Suppliers of water for community public water systems shall collect and analyze one sample per plant at the entry point of the distribution system for the determination of sodium concentration levels; samples must be collected and analyzed annually for systems utilizing surface water sources in whole or in part, and at least every three years for systems utilizing solely ground water sources. The minimum number of samples required to be taken by the system shall be based on the number of treatment plants used by the system, except that multiple wells drawing raw water from a single aquifer may, with the State approval, be considered one treatment plant for determining the minimum number of samples. The supplier of water may be required by the State to collect and analyze water samples for sodium more frequently in locations where the sodium content is variable.

(b) The supplier of water shall report to EPA and/or the State the results of the analyses for sodium within the first 10 days of the month following the month in which the sample results were received or within the first 10 days following the end of the required monitoring period as stipulated by the State, whichever of these is first. If more than annual sampling is required the supplier shall report the average sodium concentration within 10 days of the month following the month in which the analytical results of the last sample used for the annual average was received. The supplier of water shall not be required to report the results to EPA where the State has adopted this regulation and results are reported to the State. The supplier shall report the results to EPA where the State has not adopted this regulation.

(c) The supplier of water shall notify appropriate local and State public health officials of the sodium levels by written notice by direct mail within three months. A copy of each notice required to be provided by this paragraph shall be sent to EPA and/or the State within 10 days of its issuance. The supplier of water is not required to notify appropriate local and State public health officials of the sodium levels where the State provides such notices in lieu of the supplier.

(d) Analyses for sodium shall be conducted as directed in § 141.23(k)(1).

[45 FR 57345, Aug. 27, 1980, as amended at 59 FR 62470, Dec. 5, 1994]

§ 141.42 Special monitoring for corrosivity characteristics.

(a-c) [Reserved]

(d) Community water supply systems shall identify whether the following construction materials are present in their distribution system and report to the State:

Lead from piping, solder, caulking, interior lining of distribution mains, alloys and home plumbing.

Copper from piping and alloys, service lines, and home plumbing.

Galvanized piping, service lines, and home plumbing.

Ferrous piping materials such as cast iron and steel.

Asbestos cement pipe.

In addition, States may require identification and reporting of other materials of construction present in distribution systems that may contribute contaminants to the drinking water, such as:

Vinyl lined asbestos cement pipe.

Coal tar lined pipes and tanks.

[45 FR 57346, Aug. 27, 1980; 47 FR 10999, Mar. 12, 1982, as amended at 59 FR 62470, Dec. 5, 1994]

Subpart F - Maximum Contaminant Level Goals and Maximum Residual Disinfectant Level Goals
§ 141.50 Maximum contaminant level goals for organic contaminants.

(a) MCLGs are zero for the following contaminants:

(1) Benzene

(2) Vinyl chloride

(3) Carbon tetrachloride

(4) 1,2-dichloroethane

(5) Trichloroethylene

(6) Acrylamide

(7) Alachlor

(8) Chlordane

(9) Dibromochloropropane

(10) 1,2-Dichloropropane

(11) Epichlorohydrin

(12) Ethylene dibromide

(13) Heptachlor

(14) Heptachlor epoxide

(15) Pentachlorophenol

(16) Polychlorinated biphenyls (PCBs)

(17) Tetrachloroethylene

(18) Toxaphene

(19) Benzo[a]pyrene

(20) Dichloromethane (methylene chloride)

(21) Di(2-ethylhexyl)phthalate

(22) Hexachlorobenzene

(23) 2,3,7,8-TCDD (Dioxin)

(b) MCLGs for the following contaminants are as indicated:

Contaminant MCLG in mg/l
(1) 1,1-Dichloroethylene 0.007
(2) 1,1,1-Trichloroethane 0.20
(3) para-Dichlorobenzene 0.075
(4) Aldicarb 0.001
(5) Aldicarb sulfoxide 0.001
(6) Aldicarb sulfone 0.001
(7) Atrazine 0.003
(8) Carbofuran 0.04
(9) o-Dichlorobenzene 0.6
(10) cis-1,2-Dichloroethylene 0.07
(11) trans-1,2-Dichloroethylene 0.1
(12) 2,4-D 0.07
(13) Ethylbenzene 0.7
(14) Lindane 0.0002
(15) Methoxychlor 0.04
(16) Monochlorobenzene 0.1
(17) Styrene 0.1
(18) Toluene 1
(19) 2,4,5-TP 0.05
(20) Xylenes (total) 10
(21) Dalapon 0.2
(22) Di(2-ethylhexyl)adipate .4
(23) Dinoseb .007
(24) Diquat .02
(25) Endothall .1
(26) Endrin .002
(27) Glyphosate .7
(28) Hexachlorocyclopentadiene .05
(29) Oxamyl (Vydate) .2
(30) Picloram .5
(31) Simazine .004
(32) 1,2,4-Trichlorobenzene .07
(33) 1,1,2-Trichloroethane .003

[50 FR 46901, Nov. 13, 1985, as amended at 52 FR 20674, June 2, 1987; 52 FR 25716, July 8, 1987; 56 FR 3592, Jan. 30, 1991; 56 FR 30280, July 1, 1991; 57 FR 31846, July 17, 1992]

§ 141.51 Maximum contaminant level goals for inorganic contaminants.

(a) [Reserved]

(b) MCLGs for the following contaminants are as indicated:

Contaminant MCLG (mg/l)
Antimony 0.006
Arsenic zero1
Asbestos 7 Million fibers/liter (longer than 10 µm).
Barium 2
Beryllium .004
Cadmium 0.005
Chromium 0.1
Copper 1.3
Cyanide (as free Cyanide) .2
Fluoride 4.0
Lead zero
Mercury 0.002
Nitrate 10 (as Nitrogen).
Nitrite 1 (as Nitrogen).
Total Nitrate + Nitrite 10 (as Nitrogen).
Selenium 0.05
Thallium .0005

[50 FR 47155, Nov. 14, 1985, as amended at 52 FR 20674, June 2, 1987; 56 FR 3593, Jan. 30, 1991; 56 FR 26548, June 7, 1991; 56 FR 30280, July 1, 1991; 57 FR 31846, July 17, 1992; 60 FR 33932, June 29, 1995; 66 FR 7063, Jan. 22, 2001]

§ 141.52 Maximum contaminant level goals for microbiological contaminants.

(a) MCLGs for the following contaminants are as indicated:

Contaminant MCLG
(1) Giardia lamblia zero
(2) Viruses zero
(3) Legionella zero
(4) Total coliforms (including fecal) zero
coliforms and Escherichia coli
(5) Cryptosporidium zero
(6) Escherichia coli (E. coli) zero

(b) The MCLG identified in paragraph (a)(4) of this section is applicable until March 31, 2016. The MCLG identified in paragraph (a)(6) of this section is applicable beginning April 1, 2016.

[78 FR 10347, Feb. 13, 2013]

§ 141.53 Maximum contaminant level goals for disinfection byproducts.

MCLGs for the following disinfection byproducts are as indicated:

Disinfection byproduct MCLG
(mg/L)
Bromodichloromethane zero
Bromoform zero
Bromate zero
Chlorite 0.8
Chloroform 0.07
Dibromochloromethane 0.06
Dichloroacetic acid zero
Monochloroacetic acid 0.07
Trichloroacetic acid 0.02

[63 FR 69465, Dec. 16, 1998, as amended at 65 FR 34405, May 30, 2000; 71 FR 478, Jan. 4, 2006]

§ 141.54 Maximum residual disinfectant level goals for disinfectants.

MRDLGs for disinfectants are as follows:

Disinfectant residual MRDLG(mg/L)
Chlorine 4 (as Cl2).
Chloramines 4 (as Cl2).
Chlorine dioxide 0.8 (as ClO2)

[63 FR 69465, Dec. 16, 1998]

§ 141.55 Maximum contaminant level goals for radionuclides.

MCLGs for radionuclides are as indicated in the following table:

Contaminant MCLG
1. Combined radium-226 and radium-228 Zero.
2. Gross alpha particle activity (excluding radon and uranium) Zero.
3. Beta particle and photon radioactivity Zero.
4. Uranium Zero.

[65 FR 76748, Dec. 7, 2000]

Subpart G - National Primary Drinking Water Regulations: Maximum Contaminant Levels and Maximum Residual Disinfectant Levels
§ 141.60 Effective dates.

(a) The effective dates for § 141.61 are as follows:

(1) The effective date for paragraphs (a)(1) through (a)(8) of § 141.61 is January 9, 1989.

(2) The effective date for paragraphs (a)(9) through (a)(18) and (c)(1) through (c)(18) of § 141.61 is July 30, 1992.

(3) The effective date for paragraphs (a)(19) through (a)(21), (c)(19) through (c)(25), and (c)(27) through (c)(33) of § 141.61 is January 17, 1994. The effective date of § 141.61(c)(26) is August 17, 1992.

(b) The effective dates for § 141.62 are as follows:

(1) The effective date of paragraph (b)(1) of § 141.62 is October 2, 1987.

(2) The effective date for paragraphs (b)(2) and (b)(4) through (b)(10) of § 141.62 is July 30, 1992.

(3) The effective date for paragraphs (b)(11) through (b)(15) of § 141.62 is January 17, 1994.

(4) The effective date for § 141.62(b)(16) is January 23, 2006.

[56 FR 3593, Jan. 30, 1991, as amended at 57 FR 31846, July 17, 1992; 59 FR 34324, July 1, 1994; 66 FR 7063, Jan. 22, 2001]

§ 141.61 Maximum contaminant levels for organic contaminants.

(a) The following maximum contaminant levels for organic contaminants apply to community and non-transient, non-community water systems.

CAS No. Contaminant MCL (mg/l)
(1) 75-01-4 Vinyl chloride 0.002
(2) 71-43-2 Benzene 0.005
(3) 56-23-5 Carbon tetrachloride 0.005
(4) 107-06-2 1,2-Dichloroethane 0.005
(5) 79-01-6 Trichloroethylene 0.005
(6) 106-46-7 para-Dichlorobenzene 0.075
(7) 75-35-4 1,1-Dichloroethylene 0.007
(8) 71-55-6 1,1,1-Trichloroethane 0.2
(9) 156-59-2 cis-1,2-Dichloroethylene 0.07
(10) 78-87-5 1,2-Dichloropropane 0.005
(11) 100-41-4 Ethylbenzene 0.7
(12) 108-90-7 Monochlorobenzene 0.1
(13) 95-50-1 o-Dichlorobenzene 0.6
(14) 100-42-5 Styrene 0.1
(15) 127-18-4 Tetrachloroethylene 0.005
(16) 108-88-3 Toluene 1
(17) 156-60-5 trans-1,2-Dichloroethylene 0.1
(18) 1330-20-7 Xylenes (total) 10
(19) 75-09-2 Dichloromethane 0.005
(20) 120-82-1 1,2,4-Trichloro- benzene .07
(21) 79-00-5 1,1,2-Trichloro- ethane .005

(b) The Administrator, pursuant to section 1412 of the Act, hereby identifies as indicated in the Table below granular activated carbon (GAC), packed tower aeration (PTA), or oxidation (OX) as the best technology treatment technique, or other means available for achieving compliance with the maximum contaminant level for organic contaminants identified in paragraphs (a) and (c) of this section:

BAT for Organic Contaminants Listed in § 141.61 (a) and (c)

CAS No. Contaminant GAC PTA OX
15972-60-8 Alachlor X
116-06-3 Aldicarb X
1646-88-4 Aldicarb sulfone X
1646-87-3 Aldicarb sulfoxide X
1912-24-9 Atrazine X
71-43-2 Benzene X X
50-32-8 Benzo[a]pyrene X
1563-66-2 Carbofuran X
56-23-5 Carbon tetrachloride X X
57-74-9 Chlordane X
75-99-0 Dalapon X
94-75-7 2,4-D X
103-23-1 Di (2-ethylhexyl) adipate X X
117-81-7 Di (2-ethylhexyl) phthalate X
96-12-8 Dibromochloropropane (DBCP) X X
95-50-1 o-Dichlorobenzene X X
106-46-7 para-Dichlorobenzene X X
107-06-2 1,2-Dichloroethane X X
75-35-4 1,1-Dichloroethylene X X
156-59-2 cis-1,2-Dichloroethylene X X
156-60-5 trans-1,2-Dichloroethylene X X
75-09-2 Dichloromethane X
78-87-5 1,2-Dichloropropane X X
88-85-7 Dinoseb X
85-00-7 Diquat X
145-73-3 Endothall X
72-20-8 Endrin X
100-41-4 Ethylbenzene X X
106-93-4 Ethylene Dibromide (EDB) X X
1071-83-6 Gylphosate X
76-44-8 Heptachlor X
1024-57-3 Heptachlor epoxide X
118-74-1 Hexachlorobenzene X
77-47-3 Hexachlorocyclopentadiene X X
58-89-9 Lindane X
72-43-5 Methoxychlor X
108-90-7 Monochlorobenzene X X
23135-22-0 Oxamyl (Vydate) X
87-86-5 Pentachlorophenol X
1918-02-1 Picloram X
1336-36-3 Polychlorinated biphenyls (PCB) X
122-34-9 Simazine X
100-42-5 Styrene X X
1746-01-6 2,3,7,8-TCDD (Dioxin) X
127-18-4 Tetrachloroethylene X X
108-88-3 Toluene X X
8001-35-2 Toxaphene X
93-72-1 2,4,5-TP (Silvex) X
120-82-1 1,2,4-Trichlorobenzene X X
71-55-6 1,1,1-Trichloroethane X X
79-00-5 1,1,2-Trichloroethane X X
79-01-6 Trichloroethylene X X
75-01-4 Vinyl chloride X
1330-20-7 Xylene X X

(c) The following maximum contaminant levels for synthetic organic contaminants apply to community water systems and non-transient, non-community water systems:

CAS No. Contaminant MCL (mg/l)
(1) 15972-60-8 Alachlor 0.002
(2) 116-06-3 Aldicarb 0.003
(3) 1646-87-3 Aldicarb sulfoxide 0.004
(4) 1646-87-4 Aldicarb sulfone 0.002
(5) 1912-24-9 Atrazine 0.003
(6) 1563-66-2 Carbofuran 0.04
(7) 57-74-9 Chlordane 0.002
(8) 96-12-8 Dibromochloropropane 0.0002
(9) 94-75-7 2,4-D 0.07
(10) 106-93-4 Ethylene dibromide 0.00005
(11) 76-44-8 Heptachlor 0.0004
(12) 1024-57-3 Heptachlor epoxide 0.0002
(13) 58-89-9 Lindane 0.0002
(14) 72-43-5 Methoxychlor 0.04
(15) 1336-36-3 Polychlorinated biphenyls 0.0005
(16) 87-86-5 Pentachlorophenol 0.001
(17) 8001-35-2 Toxaphene 0.003
(18) 93-72-1 2,4,5-TP 0.05
(19) 50-32-8 Benzo[a]pyrene 0.0002
(20) 75-99-0 Dalapon 0.2
(21) 103-23-1 Di(2-ethylhexyl) adipate 0.4
(22) 117-81-7 Di(2-ethylhexyl) phthalate 0.006
(23) 88-85-7 Dinoseb 0.007
(24) 85-00-7 Diquat 0.02
(25) 145-73-3 Endothall 0.1
(26) 72-20-8 Endrin 0.002
(27) 1071-53-6 Glyphosate 0.7
(28) 118-74-1 Hexacholorbenzene 0.001
(29) 77-47-4 Hexachlorocyclopentadiene 0.05
(30) 23135-22-0 Oxamyl (Vydate) 0.2
(31) 1918-02-1 Picloram 0.5
(32) 122-34-9 Simazine 0.004
(33) 1746-01-6 2,3,7,8-TCDD (Dioxin) 3 × 10−8

[56 FR 3593, Jan. 30, 1991, as amended at 56 FR 30280, July 1, 1991; 57 FR 31846, July 17, 1992; 59 FR 34324, July 1, 1994]

§ 141.62 Maximum contaminant levels for inorganic contaminants.

(a) [Reserved]

(b) The maximum contaminant levels for inorganic contaminants specified in paragraphs (b) (2)-(6), (b)(10), and (b) (11)-(16) of this section apply to community water systems and non-transient, non-community water systems. The maximum contaminant level specified in paragraph (b)(1) of this section only applies to community water systems. The maximum contaminant levels specified in (b)(7), (b)(8), and (b)(9) of this section apply to community water systems; non-transient, non-community water systems; and transient non-community water systems.

Contaminant MCL (mg/l)
(1) Fluoride 4.0
(2) Asbestos 7 Million Fibers/liter (longer than 10 µm).
(3) Barium 2
(4) Cadmium 0.005
(5) Chromium 0.1
(6) Mercury 0.002
(7) Nitrate 10 (as Nitrogen)
(8) Nitrite 1 (as Nitrogen)
(9) Total Nitrate and Nitrite 10 (as Nitrogen)
(10) Selenium 0.05
(11) Antimony 0.006
(12) Beryllium 0.004
(13) Cyanide (as free Cyanide) 0.2
(14) [Reserved]
(15) Thallium 0.002
(16) Arsenic 0.010

(c) The Administrator, pursuant to section 1412 of the Act, hereby identifies the following as the best technology, treatment technique, or other means available for achieving compliance with the maximum contaminant levels for inorganic contaminants identified in paragraph (b) of this section, except fluoride:

BAT for Inorganic Compounds Listed in Section 141.62(b)

Chemical Name BAT(s)
Antimony 2,7
Arsenic4 1, 2, 5, 6, 7, 9, 125
Asbestos 2,3,8
Barium 5,6,7,9
Beryllium 1,2,5,6,7
Cadmium 2,5,6,7
Chromium 2,5,62,7
Cyanide 5,7,13
Mercury 21,4,61,71
Nickel 5,6,7
Nitrate 5,7,9
Nitrite 5,7
Selenium 1,23,6,7,9
Thallium 1,5

Key to BATS in Table

1 = Activated Alumina

2 = Coagulation/Filtration (not BAT for systems <500 service connections)

3 = Direct and Diatomite Filtration

4 = Granular Activated Carbon

5 = Ion Exchange

6 = Lime Softening (not BAT for systems <500 service connections)

7 = Reverse Osmosis

8 = Corrosion Control

9 = Electrodialysis

10 = Chlorine

11 = Ultraviolet

12 = Oxidation/Filtration

13 = Alkaline Chlorination (pH ≥8.5)

(d) The Administrator, pursuant to section 1412 of the Act, hereby identifies in the following table the affordable technology, treatment technique, or other means available to systems serving 10,000 persons or fewer for achieving compliance with the maximum contaminant level for arsenic:

Small System Compliance Technologies (SSCTs)1 for Arsenic2

Small system compliance technology Affordable for listed small system categories3
Activated Alumina (centralized) All size categories.
Activated Alumina (Point-of-Use)4 All size categories.
Coagulation/Filtration5 501-3,300, 3,301-10,000.
Coagulation-assisted Microfiltration 501-3,300, 3,301-10,000.
Electrodialysis reversal6 501-3,300, 3,301-10,000.
Enhanced coagulation/filtration All size categories
Enhanced lime softening (pH>10.5) All size categories.
Ion Exchange All size categories.
Lime Softening5 501-3,300, 3,301-10,000.
Oxidation/Filtration7 All size categories.
Reverse Osmosis (centralized)6 501-3,300, 3,301-10,000.
Reverse Osmosis (Point-of-Use)4 All size categories.

[56 FR 3594, Jan. 30, 1991, as amended at 56 FR 30280, July 1, 1991; 57 FR 31847, July 17, 1992; 59 FR 34325, July 1, 1994; 60 FR 33932, June 29, 1995; 66 FR 7063, Jan. 22, 2001; 68 FR 14506, Mar. 25, 2003; 69 FR 38855, June 29, 2004]

§ 141.63 Maximum contaminant levels (MCLs) for microbiological contaminants.

(a) Until March 31, 2016, the total coliform MCL is based on the presence or absence of total coliforms in a sample, rather than coliform density.

(1) For a system that collects at least 40 samples per month, if no more than 5.0 percent of the samples collected during a month are total coliform-positive, the system is in compliance with the MCL for total coliforms.

(2) For a system that collects fewer than 40 samples per month, if no more than one sample collected during a month is total coliform-positive, the system is in compliance with the MCL for total coliforms.

(b) Until March 31, 2016, any fecal coliform-positive repeat sample or E. coli-positive repeat sample, or any total coliform-positive repeat sample following a fecal coliform-positive or E. coli-positive routine sample, constitutes a violation of the MCL for total coliforms. For purposes of the public notification requirements in subpart Q of this part, this is a violation that may pose an acute risk to health.

(c) Beginning April 1, 2016, a system is in compliance with the MCL for E. coli for samples taken under the provisions of subpart Y of this part unless any of the conditions identified in paragraphs (c)(1) through (c)(4) of this section occur. For purposes of the public notification requirements in subpart Q of this part, violation of the MCL may pose an acute risk to health.

(1) The system has an E. coli-positive repeat sample following a total coliform-positive routine sample.

(2) The system has a total coliform-positive repeat sample following an E. coli-positive routine sample.

(3) The system fails to take all required repeat samples following an E. coli-positive routine sample.

(4) The system fails to test for E. coli when any repeat sample tests positive for total coliform.

(d) Until March 31, 2016, a public water system must determine compliance with the MCL for total coliforms in paragraphs (a) and (b) of this section for each month in which it is required to monitor for total coliforms. Beginning April 1, 2016, a public water system must determine compliance with the MCL for E. coli in paragraph (c) of this section for each month in which it is required to monitor for total coliforms.

(e) The Administrator, pursuant to section 1412 of the Act, hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant level for total coliforms in paragraphs (a) and (b) of this section and for achieving compliance with the maximum contaminant level for E. coli in paragraph (c) of this section:

(1) Protection of wells from fecal contamination by appropriate placement and construction;

(2) Maintenance of a disinfectant residual throughout the distribution system;

(3) Proper maintenance of the distribution system including appropriate pipe replacement and repair procedures, main flushing programs, proper operation and maintenance of storage tanks and reservoirs, cross connection control, and continual maintenance of positive water pressure in all parts of the distribution system;

(4) Filtration and/or disinfection of surface water, as described in subparts H, P, T, and W of this part, or disinfection of ground water, as described in subpart S of this part, using strong oxidants such as chlorine, chlorine dioxide, or ozone; and

(5) For systems using ground water, compliance with the requirements of an EPA-approved State Wellhead Protection Program developed and implemented under section 1428 of the SDWA.

(f) The Administrator, pursuant to section 1412 of the Act, hereby identifies the technology, treatment techniques, or other means available identified in paragraph (e) of this section as affordable technology, treatment techniques, or other means available to systems serving 10,000 or fewer people for achieving compliance with the maximum contaminant level for total coliforms in paragraphs (a) and (b) of this section and for achieving compliance with the maximum contaminant level for E. coli in paragraph (c) of this section.

[78 FR 10347, Feb. 13, 2013]

§ 141.64 Maximum contaminant levels for disinfection byproducts.

(a) Bromate and chlorite. The maximum contaminant levels (MCLs) for bromate and chlorite are as follows:

Disinfection byproduct MCL (mg/L)
Bromate 0.010
Chlorite 1.0

(1) Compliance dates for CWSs and NTNCWSs. Subpart H systems serving 10,000 or more persons must comply with this paragraph (a) beginning January 1, 2002. Subpart H systems serving fewer than 10,000 persons and systems using only ground water not under the direct influence of surface water must comply with this paragraph (a) beginning January 1, 2004.

(2) The Administrator, pursuant to section 1412 of the Act, hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for bromate and chlorite identified in this paragraph (a):

Disinfection byproduct Best available technology
Bromate Control of ozone treatment process to reduce production of bromate
Chlorite Control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes to reduce disinfectant levels

(b) TTHM and HAA5.

(1) Subpart L - RAA compliance.

(i) Compliance dates. Subpart H systems serving 10,000 or more persons must comply with this paragraph (b)(1) beginning January 1, 2002. Subpart H systems serving fewer than 10,000 persons and systems using only ground water not under the direct influence of surface water must comply with this paragraph (b)(1) beginning January 1, 2004. All systems must comply with these MCLs until the date specified for subpart V compliance in § 141.620(c).

Disinfection byproduct MCL (mg/L)
Total trihalomethanes (TTHM) 0.080
Haloacetic acids (five) (HAA5) 0.060

(ii) The Administrator, pursuant to section 1412 of the Act, hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for TTHM and HAA5 identified in this paragraph (b)(1):

Disinfection byproduct Best available technology
Total trihalomethanes (TTHM) and Haloacetic acids (five) (HAA5) Enhanced coagulation or enhanced softening or GAC10, with chlorine as the primary and residual disinfectant

(2) Subpart V - LRAA compliance.

(i) Compliance dates. The subpart V MCLs for TTHM and HAA5 must be complied with as a locational running annual average at each monitoring location beginning the date specified for subpart V compliance in § 141.620(c).

Disinfection byproduct MCL (mg/L)
Total trihalomethanes (TTHM) 0.080
Haloacetic acids (five) (HAA5) 0.060

(ii) The Administrator, pursuant to section 1412 of the Act, hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for TTHM and HAA5 identified in this paragraph (b)(2) for all systems that disinfect their source water:

Disinfection byproduct Best available technology
Total trihalomethanes (TTHM) and Haloacetic acids (five) (HAA5) Enhanced coagulation or enhanced softening, plus GAC10; or nanofiltration with a molecular weight cutoff ≤1000 Daltons; or GAC20

(iii) The Administrator, pursuant to section 1412 of the Act, hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the maximum contaminant levels for TTHM and HAA5 identified in this paragraph (b)(2) for consecutive systems and applies only to the disinfected water that consecutive systems buy or otherwise receive:

Disinfection byproduct Best available technology
Total trihalomethanes (TTHM) and Haloacetic acids (five) (HAA5) Systems serving ≥10,000: Improved distribution system and storage tank management to reduce residence time, plus the use of chloramines for disinfectant residual maintenance
Systems serving <10,000: Improved distribution system and storage tank management to reduce residence time

[71 FR 478, Jan. 4, 2006]

§ 141.65 Maximum residual disinfectant levels.

(a) Maximum residual disinfectant levels (MRDLs) are as follows:

Disinfectant residual MRDL (mg/L)
Chlorine 4.0 (as Cl2).
Chloramines 4.0 (as Cl2).
Chlorine dioxide 0.8 (as ClO2).

(b) Compliance dates -

(1) CWSs and NTNCWSs. Subpart H systems serving 10,000 or more persons must comply with this section beginning January 1, 2002. Subpart H systems serving fewer than 10,000 persons and systems using only ground water not under the direct influence of surface water must comply with this subpart beginning January 1, 2004.

(2) Transient NCWSs. Subpart H systems serving 10,000 or more persons and using chlorine dioxide as a disinfectant or oxidant must comply with the chlorine dioxide MRDL beginning January 1, 2002. Subpart H systems serving fewer than 10,000 persons and using chlorine dioxide as a disinfectant or oxidant and systems using only ground water not under the direct influence of surface water and using chlorine dioxide as a disinfectant or oxidant must comply with the chlorine dioxide MRDL beginning January 1, 2004.

(c) The Administrator, pursuant to Section 1412 of the Act, hereby identifies the following as the best technology, treatment techniques, or other means available for achieving compliance with the maximum residual disinfectant levels identified in paragraph (a) of this section: control of treatment processes to reduce disinfectant demand and control of disinfection treatment processes to reduce disinfectant levels.

[63 FR 69465, Dec. 16, 1998, as amended at 66 FR 3776, Jan. 16, 2001]

§ 141.66 Maximum contaminant levels for radionuclides.

(a) [Reserved]

(b) MCL for combined radium-226 and -228. The maximum contaminant level for combined radium-226 and radium-228 is 5 pCi/L. The combined radium-226 and radium-228 value is determined by the addition of the results of the analysis for radium-226 and the analysis for radium-228.

(c) MCL for gross alpha particle activity (excluding radon and uranium). The maximum contaminant level for gross alpha particle activity (including radium-226 but excluding radon and uranium) is 15 pCi/L.

(d) MCL for beta particle and photon radioactivity.

(1) The average annual concentration of beta particle and photon radioactivity from man-made radionuclides in drinking water must not produce an annual dose equivalent to the total body or any internal organ greater than 4 millirem/year (mrem/year).

(2) Except for the radionuclides listed in table A, the concentration of man-made radionuclides causing 4 mrem total body or organ dose equivalents must be calculated on the basis of 2 liter per day drinking water intake using the 168 hour data list in “Maximum Permissible Body Burdens and Maximum Permissible Concentrations of Radionuclides in Air and in Water for Occupational Exposure,” NBS (National Bureau of Standards) Handbook 69 as amended August 1963, U.S. Department of Commerce. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of this document are available from the National Technical Information Service, NTIS ADA 280 282, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161. The toll-free number is 800-553-6847. Copies may be inspected at EPA's Drinking Water Docket, 401 M Street, SW., Washington, DC 20460; or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html. If two or more radionuclides are present, the sum of their annual dose equivalent to the total body or to any organ shall not exceed 4 mrem/year.

Table A - Average Annual Concentrations Assumed To Produce: a Total Body or Organ Dose of 4 mrem/yr

1. Radionuclide Critical organ pCi per liter
2. Tritium Total body 20,000
3. Strontium-90 Bone Marrow 8

(e) MCL for uranium. The maximum contaminant level for uranium is 30 µg/L.

(f) Compliance dates.

(1) Compliance dates for combined radium-226 and -228, gross alpha particle activity, gross beta particle and photon radioactivity, and uranium: Community water systems must comply with the MCLs listed in paragraphs (b), (c), (d), and (e) of this section beginning December 8, 2003 and compliance shall be determined in accordance with the requirements of §§ 141.25 and 141.26. Compliance with reporting requirements for the radionuclides under appendix A to subpart O and appendices A and B to subpart Q is required on December 8, 2003.

(2) [Reserved]

(g) Best available technologies (BATs) for radionuclides. The Administrator, pursuant to section 1412 of the Act, hereby identifies as indicated in the following table the best technology available for achieving compliance with the maximum contaminant levels for combined radium-226 and -228, uranium, gross alpha particle activity, and beta particle and photon radioactivity.

Table B - BAT for Combined Radium-226 and Radium-228, Uranium, Gross Alpha Particle Activity, and Beta Particle and Photon Radioactivity

Contaminant BAT
1. Combined radium-226 and radium-228 Ion exchange, reverse osmosis, lime softening.
2. Uranium Ion exchange, reverse osmosis, lime softening, coagulation/filtration.
3. Gross alpha particle activity (excluding Radon and Uranium) Reverse osmosis.
4. Beta particle and photon radioactivity Ion exchange, reverse osmosis.

(h) Small systems compliance technologies list for radionuclides.

Table C - List of Small Systems Compliance Technologies for Radionuclides and Limitations to Use

Unit technologies Limitations (see footnotes) Operator skill level required1 Raw water quality range and
considerations.1
1. Ion exchange (IE) (a) Intermediate All ground waters.
2. Point of use (POU2) IE (b) Basic All ground waters.
3. Reverse osmosis (RO) (c) Advanced Surface waters usually require pre-filtration.
4. POU2 RO (b) Basic Surface waters usually require pre-filtration.
5. Lime softening (d) Advanced All waters.
6. Green sand filtration (e) Basic.
7. Co-precipitation with Barium sulfate (f) Intermediate to Advanced Ground waters with suitable water quality.
8. Electrodialysis/electrodialysis reversal Basic to Intermediate All ground waters.
9. Pre-formed hydrous Manganese oxide filtration (g) Intermediate All ground waters.
10. Activated alumina (a), (h) Advanced All ground waters; competing anion concentrations may affect regeneration frequency.
11. Enhanced coagulation/filtration (i) Advanced Can treat a wide range of water qualities.

Table D - Compliance Technologies by System Size Category for Radionuclide NPDWR's

Contaminant Compliance technologies1 for system size categories (population served) 3,300-10,000
25-500 501-3,300
1. Combined radium-226 and radium-228 1, 2, 3, 4, 5, 6, 7, 8, 9 1, 2, 3, 4, 5, 6, 7, 8, 9 1, 2, 3, 4, 5, 6, 7. 8, 9.
2. Gross alpha particle activity 3, 4 3, 4 3, 4.
3. Beta particle activity and photon activity 1, 2, 3, 4 1, 2, 3, 4 1, 2, 3, 4.
4. Uranium 1, 2, 4, 10, 11 1, 2, 3, 4, 5, 10, 11 1, 2, 3, 4, 5, 10, 11.

[65 FR 76748, Dec. 7, 2000]

Subpart H - Filtration and Disinfection
Source:

54 FR 27527, June 29, 1989, unless otherwise noted.

§ 141.70 General requirements.

(a) The requirements of this subpart H constitute national primary drinking water regulations. These regulations establish criteria under which filtration is required as a treatment technique for public water systems supplied by a surface water source and public water systems supplied by a ground water source under the direct influence of surface water. In addition, these regulations establish treatment technique requirements in lieu of maximum contaminant levels for the following contaminants: Giardia lamblia, viruses, heterotrophic plate count bacteria, Legionella, and turbidity. Each public water system with a surface water source or a ground water source under the direct influence of surface water must provide treatment of that source water that complies with these treatment technique requirements. The treatment technique requirements consist of installing and properly operating water treatment processes which reliably achieve:

(1) At least 99.9 percent (3-log) removal and/or inactivation of Giardia lamblia cysts between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer; and

(2) At least 99.99 percent (4-log) removal and/or inactivation of viruses between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer.

(b) A public water system using a surface water source or a ground water source under the direct influence of surface water is considered to be in compliance with the requirements of paragraph (a) of this section if:

(1) It meets the requirements for avoiding filtration in § 141.71 and the disinfection requirements in § 141.72(a); or

(2) It meets the filtration requirements in § 141.73 and the disinfection requirements in § 141.72(b).

(c) Each public water system using a surface water source or a ground water source under the direct influence of surface water must be operated by qualified personnel who meet the requirements specified by the State.

(d) Additional requirements for systems serving at least 10,000 people. In addition to complying with requirements in this subpart, systems serving at least 10,000 people must also comply with the requirements in subpart P of this part.

(e) Additional requirements for systems serving fewer than 10,000 people. In addition to complying with requirements in this subpart, systems serving fewer than 10,000 people must also comply with the requirements in subpart T of this part.

[54 FR 27527, June 29, 1989, as amended at 63 FR 69516, Dec. 16, 1998; 67 FR 1836, Jan. 14, 2002]

§ 141.71 Criteria for avoiding filtration.

A public water system that uses a surface water source must meet all of the conditions of paragraphs (a) and (b) of this section, and is subject to paragraph (c) of this section, beginning December 30, 1991, unless the State has determined, in writing pursuant to § 1412(b)(7)(C)(iii), that filtration is required. A public water system that uses a ground water source under the direct influence of surface water must meet all of the conditions of paragraphs (a) and (b) of this section and is subject to paragraph (c) of this section, beginning 18 months after the State determines that it is under the direct influence of surface water, or December 30, 1991, whichever is later, unless the State has determined, in writing pursuant to § 1412(b)(7)(C)(iii), that filtration is required. If the State determines in writing pursuant to § 1412(b)(7)(C)(iii) before December 30, 1991, that filtration is required, the system must have installed filtration and meet the criteria for filtered systems specified in §§ 141.72(b) and 141.73 by June 29, 1993. Within 18 months of the failure of a system using surface water or a ground water source under the direct influence of surface water to meet any one of the requirements of paragraphs (a) and (b) of this section or after June 29, 1993, whichever is later, the system must have installed filtration and meet the criteria for filtered systems specified in §§ 141.72(b) and 141.73.

(a) Source water quality conditions.

(1) The fecal coliform concentration must be equal to or less than 20/100 ml, or the total coliform concentration must be equal to or less than 100/100 ml (measured as specified in § 141.74 (a) (1) and (2) and (b)(1)), in representative samples of the source water immediately prior to the first or only point of disinfectant application in at least 90 percent of the measurements made for the 6 previous months that the system served water to the public on an ongoing basis. If a system measures both fecal and total coliforms, the fecal coliform criterion, but not the total coliform criterion, in this paragraph must be met.

(2) The turbidity level cannot exceed 5 NTU (measured as specified in § 141.74 (a)(1) and (b)(2)) in representative samples of the source water immediately prior to the first or only point of disinfectant application unless:

(i) the State determines that any such event was caused by circumstances that were unusual and unpredictable; and

(ii) as a result of any such event, there have not been more than two events in the past 12 months the system served water to the public, or more than five events in the past 120 months the system served water to the public, in which the turbidity level exceeded 5 NTU. An “event” is a series of consecutive days during which at least one turbidity measurement each day exceeds 5 NTU.

(b) Site-specific conditions.

(1)

(i) The public water system must meet the requirements of § 141.72(a)(1) at least 11 of the 12 previous months that the system served water to the public, on an ongoing basis, unless the system fails to meet the requirements during 2 of the 12 previous months that the system served water to the public, and the State determines that at least one of these failures was caused by circumstances that were unusual and unpredictable.

(ii) The public water system must meet the requirements of § 141.72(a)(2) at all times the system serves water to the public.

(iii) The public water system must meet the requirements of § 141.72(a)(3) at all times the system serves water to the public unless the State determines that any such failure was caused by circumstances that were unusual and unpredictable.

(iv) The public water system must meet the requirements of § 141.72(a)(4) on an ongoing basis unless the State determines that failure to meet these requirements was not caused by a deficiency in treatment of the source water.

(2) The public water system must maintain a watershed control program which minimizes the potential for contamination by Giardia lamblia cysts and viruses in the source water. The State must determine whether the watershed control program is adequate to meet this goal. The adequacy of a program to limit potential contamination by Giardia lamblia cysts and viruses must be based on: the comprehensiveness of the watershed review; the effectiveness of the system's program to monitor and control detrimental activities occurring in the watershed; and the extent to which the water system has maximized land ownership and/or controlled land use within the watershed. At a minimum, the watershed control program must:

(i) Characterize the watershed hydrology and land ownership;

(ii) Identify watershed characteristics and activities which may have an adverse effect on source water quality; and

(iii) Monitor the occurrence of activities which may have an adverse effect on source water quality.

The public water system must demonstrate through ownership and/or written agreements with landowners within the watershed that it can control all human activities which may have an adverse impact on the microbiological quality of the source water. The public water system must submit an annual report to the State that identifies any special concerns about the watershed and how they are being handled; describes activities in the watershed that affect water quality; and projects what adverse activities are expected to occur in the future and describes how the public water system expects to address them. For systems using a ground water source under the direct influence of surface water, an approved wellhead protection program developed under section 1428 of the Safe Drinking Water Act may be used, if the State deems it appropriate, to meet these requirements.

(3) The public water system must be subject to an annual on-site inspection to assess the watershed control program and disinfection treatment process. Either the State or a party approved by the State must conduct the on-site inspection. The inspection must be conducted by competent individuals such as sanitary and civil engineers, sanitarians, or technicians who have experience and knowledge about the operation and maintenance of a public water system, and who have a sound understanding of public health principles and waterborne diseases. A report of the on-site inspection summarizing all findings must be prepared every year. The on-site inspection must indicate to the State's satisfaction that the watershed control program and disinfection treatment process are adequately designed and maintained. The on-site inspection must include:

(i) A review of the effectiveness of the watershed control program;

(ii) A review of the physical condition of the source intake and how well it is protected;

(iii) A review of the system's equipment maintenance program to ensure there is low probability for failure of the disinfection process;

(iv) An inspection of the disinfection equipment for physical deterioration;

(v) A review of operating procedures;

(vi) A review of data records to ensure that all required tests are being conducted and recorded and disinfection is effectively practiced; and

(vii) Identification of any improvements which are needed in the equipment, system maintenance and operation, or data collection.

(4) The public water system must not have been identified as a source of a waterborne disease outbreak, or if it has been so identified, the system must have been modified sufficiently to prevent another such occurrence, as determined by the State.

(5) The public water system must comply with the maximum contaminant level (MCL) for total coliforms in § 141.63(a) and (b) and the MCL for E. coli in § 141.63(c) at least 11 months of the 12 previous months that the system served water to the public, on an ongoing basis, unless the State determines that failure to meet this requirement was not caused by a deficiency in treatment of the source water.

(6) The public water system must comply with the requirements for trihalomethanes in §§ 141.12 and 141.30 until December 31, 2001. After December 31, 2001, the system must comply with the requirements for total trihalomethanes, haloacetic acids (five), bromate, chlorite, chlorine, chloramines, and chlorine dioxide in subpart L of this part.

(c) Treatment technique violations.

(1) A system that

(i) fails to meet any one of the criteria in paragraphs (a) and (b) of this section and/or which the State has determined that filtration is required, in writing pursuant to § 1412(b)(7)(C)(iii), and

(ii) fails to install filtration by the date specified in the introductory paragraph of this section is in violation of a treatment technique requirement.

(2) A system that has not installed filtration is in violation of a treatment technique requirement if:

(i) The turbidity level (measured as specified in § 141.74(a)(1) and (b)(2)) in a representative sample of the source water immediately prior to the first or only point of disinfection application exceeds 5 NTU; or

(ii) The system is identified as a source of a waterborne disease outbreak.

[54 FR 27527, June 29, 1989, as amended at 63 FR 69516, Dec. 16, 1998; 66 FR 3776, Jan. 16, 2001; 69 FR 38855, June 29, 2004; 78 FR 10347, Feb. 13, 2013]

§ 141.72 Disinfection.

A public water system that uses a surface water source and does not provide filtration treatment must provide the disinfection treatment specified in paragraph (a) of this section beginning December 30, 1991, unless the State determines that filtration is required in writing pursuant to § 1412 (b)(7)(C)(iii). A public water system that uses a ground water source under the direct influence of surface water and does not provide filtration treatment must provide disinfection treatment specified in paragraph (a) of this section beginning December 30, 1991, or 18 months after the State determines that the ground water source is under the influence of surface water, whichever is later, unless the State has determined that filtration is required in writing pursuant to § 1412(b)(7)(C)(iii). If the State has determined that filtration is required, the system must comply with any interim disinfection requirements the State deems necessary before filtration is installed. A system that uses a surface water source that provides filtration treatment must provide the disinfection treatment specified in paragraph (b) of this section beginning June 29, 1993, or beginning when filtration is installed, whichever is later. A system that uses a ground water source under the direct influence of surface water and provides filtration treatment must provide disinfection treatment as specified in paragraph (b) of this section by June 29, 1993, or beginning when filtration is installed, whichever is later. Failure to meet any requirement of this section after the applicable date specified in this introductory paragraph is a treatment technique violation.

(a) Disinfection requirements for public water systems that do not provide filtration. Each public water system that does not provide filtration treatment must provide disinfection treatment as follows:

(1) The disinfection treatment must be sufficient to ensure at least 99.9 percent (3-log) inactivation of Giardia lamblia cysts and 99.99 percent (4-log) inactivation of viruses, every day the system serves water to the public, except any one day each month. Each day a system serves water to the public, the public water system must calculate the CT value(s) from the system's treatment parameters, using the procedure specified in § 141.74(b)(3), and determine whether this value(s) is sufficient to achieve the specified inactivation rates for Giardia lamblia cysts and viruses. If a system uses a disinfectant other than chlorine, the system may demonstrate to the State, through the use of a State-approved protocol for on-site disinfection challenge studies or other information satisfactory to the State, that CT99.9 values other than those specified in tables 2.1 and 3.1 in § 141.74(b)(3) or other operational parameters are adequate to demonstrate that the system is achieving minimum inactivation rates required by paragraph (a)(1) of this section.

(2) The disinfection system must have either

(i) redundant components, including an auxiliary power supply with automatic start-up and alarm to ensure that disinfectant application is maintained continuously while water is being delivered to the distribution system, or

(ii) automatic shut-off of delivery of water to the distribution system whenever there is less than 0.2 mg/l of residual disinfectant concentration in the water. If the State determines that automatic shut-off would cause unreasonable risk to health or interfere with fire protection, the system must comply with paragraph (a)(2)(i) of this section.

(3) The residual disinfectant concentration in the water entering the distribution system, measured as specified in § 141.74 (a)(2) and (b)(5), cannot be less than 0.2 mg/l for more than 4 hours.

(4)

(i) The residual disinfectant concentration in the distribution system, measured as total chlorine, combined chlorine, or chlorine dioxide, as specified in § 141.74 (a)(2) and (b)(6), cannot be undetectable in more than 5 percent of the samples each month, for any two consecutive months that the system serves water to the public. Water in the distribution system with a heterotrophic bacteria concentration less than or equal to 500/ml, measured as heterotrophic plate count (HPC) as specified in § 141.74(a)(1), is deemed to have a detectable disinfectant residual for purposes of determining compliance with this requirement. Thus, the value “V” in the following formula cannot exceed 5 percent in one month, for any two consecutive months.

where:

a = number of instances where the residual disinfectant concentration is measured;

b = number of instances where the residual disinfectant concentration is not measured but heterotrophic bacteria plate count (HPC) is measured;

c = number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;

d = number of instances where the residual disinfectant concentration is measured but not detected and where the HPC is >500/ml; and

e = number of instances where the residual disinfectant concentration is not measured and HPC is >500/ml.

(ii) If the State determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified by § 141.74(a)(1) and that the system is providing adequate disinfection in the distribution system, the requirements of paragraph (a)(4)(i) of this section do not apply to that system.

(b) Disinfection requirements for public water systems which provide filtration. Each public water system that provides filtration treatment must provide disinfection treatment as follows.

(1) The disinfection treatment must be sufficient to ensure that the total treatment processes of that system achieve at least 99.9 percent (3-log) inactivation and/or removal of Giardia lamblia cysts and at least 99.99 percent (4-log) inactivation and/or removal of viruses, as determined by the State.

(2) The residual disinfectant concentration in the water entering the distribution system, measured as specified in § 141.74 (a)(2) and (c)(2), cannot be less than 0.2 mg/l for more than 4 hours.

(3)

(i) The residual disinfectant concentration in the distribution system, measured as total chlorine, combined chlorine, or chlorine dioxide, as specified in § 141.74 (a)(2) and (c)(3), cannot be undetectable in more than 5 percent of the samples each month, for any two consecutive months that the system serves water to the public. Water in the distribution system with a heterotrophic bacteria concentration less than or equal to 500/ml, measured as heterotrophic plate count (HPC) as specified in § 141.74(a)(1), is deemed to have a detectable disinfectant residual for purposes of determining compliance with this requirement. Thus, the value “V” in the following formula cannot exceed 5 percent in one month, for any two consecutive months.

where:

a = number of instances where the residual disinfectant concentration is measured;

b = number of instances where the residual disinfectant concentration is not measured but heterotrophic bacteria plate count (HPC) is measured;

c = number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;

d = number of instances where no residual disinfectant concentration is detected and where the HPC is >500/ml; and

e = number of instances where the residual disinfectant concentration is not measured and HPC is >500/ml.

(ii) If the State determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified in § 141.74(a)(1) and that the system is providing adequate disinfection in the distribution system, the requirements of paragraph (b)(3)(i) of this section do not apply.

[54 FR 27527, June 29, 1989, as amended at 69 FR 38855, June 29, 2004]

§ 141.73 Filtration.

A public water system that uses a surface water source or a ground water source under the direct influence of surface water, and does not meet all of the criteria in § 141.71 (a) and (b) for avoiding filtration, must provide treatment consisting of both disinfection, as specified in § 141.72(b), and filtration treatment which complies with the requirements of paragraph (a), (b), (c), (d), or (e) of this section by June 29, 1993, or within 18 months of the failure to meet any one of the criteria for avoiding filtration in § 141.71 (a) and (b), whichever is later. Failure to meet any requirement of this section after the date specified in this introductory paragraph is a treatment technique violation.

(a) Conventional filtration treatment or direct filtration.

(1) For systems using conventional filtration or direct filtration, the turbidity level of representative samples of a system's filtered water must be less than or equal to 0.5 NTU in at least 95 percent of the measurements taken each month, measured as specified in § 141.74 (a)(1) and (c)(1), except that if the State determines that the system is capable of achieving at least 99.9 percent removal and/or inactivation of Giardia lamblia cysts at some turbidity level higher than 0.5 NTU in at least 95 percent of the measurements taken each month, the State may substitute this higher turbidity limit for that system. However, in no case may the State approve a turbidity limit that allows more than 1 NTU in more than 5 percent of the samples taken each month, measured as specified in § 141.74 (a)(1) and (c)(1).

(2) The turbidity level of representative samples of a system's filtered water must at no time exceed 5 NTU, measured as specified in § 141.74 (a)(1) and (c)(1).

(3) Beginning January 1, 2002, systems serving at least 10,000 people must meet the turbidity requirements in § 141.173(a).

(4) Beginning January 1, 2005, systems serving fewer than 10,000 people must meet the turbidity requirements in §§ 141.550 through 141.553.

(b) Slow sand filtration.

(1) For systems using slow sand filtration, the turbidity level of representative samples of a system's filtered water must be less than or equal to 1 NTU in at least 95 percent of the measurements taken each month, measured as specified in § 141.74 (a)(1) and (c)(1), except that if the State determines there is no significant interference with disinfection at a higher turbidity level, the State may substitute this higher turbidity limit for that system.

(2) The turbidity level of representative samples of a system's filtered water must at no time exceed 5 NTU, measured as specified in § 141.74 (a)(1) and (c)(1).

(c) Diatomaceous earth filtration.

(1) For systems using diatomaceous earth filtration, the turbidity level of representative samples of a system's filtered water must be less than or equal to 1 NTU in at least 95 percent of the measurements taken each month, measured as specified in § 141.74 (a)(1) and (c)(1).

(2) The turbidity level of representative samples of a system's filtered water must at no time exceed 5 NTU, measured as specified in § 141.74 (a)(1) and (c)(1).

(d) Other filtration technologies. A public water system may use a filtration technology not listed in paragraphs (a) through (c) of this section if it demonstrates to the State, using pilot plant studies or other means, that the alternative filtration technology, in combination with disinfection treatment that meets the requirements of § 141.72(b), consistently achieves 99.9 percent removal and/or inactivation of Giardia lamblia cysts and 99.99 percent removal and/or inactivation of viruses. For a system that makes this demonstration, the requirements of paragraph (b) of this section apply. Beginning January 1, 2002, systems serving at least 10,000 people must meet the requirements for other filtration technologies in § 141.173(b). Beginning January 14, 2005, systems serving fewer than 10,000 people must meet the requirements for other filtration technologies in § 141.550 through 141.553.

[54 FR 27527, June 29, 1989, as amended at 63 FR 69516, Dec. 16, 1998; 66 FR 3776, Jan. 16, 2001; 67 FR 1836, Jan. 14, 2002; 69 FR 38855, June 29, 2004]

§ 141.74 Analytical and monitoring requirements.

(a) Analytical requirements. Only the analytical method(s) specified in this paragraph, or otherwise approved by EPA, may be used to demonstrate compliance with §§ 141.71, 141.72 and 141.73. Measurements for pH, turbidity, temperature and residual disinfectant concentrations must be conducted by a person approved by the State. Measurement for total coliforms, fecal coliforms and HPC must be conducted by a laboratory certified by the State or EPA to do such analysis. Until laboratory certification criteria are developed for the analysis of fecal coliforms and HPC, any laboratory certified for total coliforms analysis by the State or EPA is deemed certified for fecal coliforms and HPC analysis. The following procedures shall be conducted in accordance with the publications listed in the following section. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies of the methods published in Standard Methods for the Examination of Water and Wastewater may be obtained from the American Public Health Association et al., 1015 Fifteenth Street, NW., Washington, DC 20005; copies of the Minimal Medium ONPG-MUG Method as set forth in the article “National Field Evaluation of a Defined Substrate Method for the Simultaneous Enumeration of Total Coliforms and Esherichia coli from Drinking Water: Comparison with the Standard Multiple Tube Fermentation Method” (Edberg et al.), Applied and Environmental Microbiology, Volume 54, pp. 1595-1601, June 1988 (as amended under Erratum, Applied and Environmental Microbiology, Volume 54, p. 3197, December, 1988), may be obtained from the American Water Works Association Research Foundation, 6666 West Quincy Avenue, Denver, Colorado, 80235; and copies of the Indigo Method as set forth in the article “Determination of Ozone in Water by the Indigo Method” (Bader and Hoigne), may be obtained from Ozone Science & Engineering, Pergamon Press Ltd., Fairview Park, Elmsford, New York 10523. Copies may be inspected at the U.S. Environmental Protection Agency, Room EB15, 401 M St., SW., Washington, DC 20460 or at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html.

(1) Public water systems must conduct analysis of pH and temperature in accordance with one of the methods listed at § 141.23(k)(1). Public water systems must conduct analysis of total coliforms, fecal coliforms, heterotrophic bacteria, and turbidity in accordance with one of the following analytical methods or one of the alternative methods listed in appendix A to subpart C of this part and by using analytical test procedures contained in Technical Notes on Drinking Water Methods, EPA-600/R-94-173, October 1994. This document is available from the National Service Center for Environmental Publications (NSCEP), P.O. Box 42419, Cincinnati, OH 45242-0419 or http://www.epa.gov/nscep/.

Organism Methodology Citation1
Total Coliform2 Total Coliform Fermentation Technique3 4 5 9221 A, B, C
Total Coliform Membrane Filter Technique6 9222 A, B, C
ONPG-MUG Test7 9223
Fecal Coliforms2 Fecal Coliform Procedure8 9221 E
Fecal Coliform Filter Procedure 9222 D
Heterotrophic bacteria2 Pour Plate Method 9215 B
SimPlate11
Turbidity13 Nephelometric Method 2130 B
Nephelometric Method 180.19
Great Lakes Instruments Method 210
Hach FilterTrak 1013312

(2) Public water systems must measure residual disinfectant concentrations with one of the analytical methods in the following table or one of the alternative methods listed in appendix A to subpart C of this part. If approved by the State, residual disinfectant concentrations for free chlorine and combined chlorine also may be measured by using DPD colorimetric test kits. In addition States may approve the use of the ITS free chlorine test strip for the determination of free chlorine. Use of the test strips is described in Method D99-003, “Free Chlorine Species (HOCl and OCl) by Test Strip,” Revision 3.0, November 21, 2003, available from Industrial Test Systems, Inc., 1875 Langston St., Rock Hill, SC 29730. Free and total chlorine residuals may be measured continuously by adapting a specified chlorine residual method for use with a continuous monitoring instrument provided the chemistry, accuracy, and precision remain the same. Instruments used for continuous monitoring must be calibrated with a grab sample measurement at least every five days, or with a protocol approved by the State.

Residual Methodology SM1 SM Online2 Other
Free Chlorine Amperometric Titration 4500-Cl D 4500-Cl D-00 D1253-033
DPD Ferrous Titrimetric 4500-Cl F 4500-Cl F-00
DPD Colorimetric 4500-Cl G 4500-Cl G-00
Syringaldazine (FACTS) 4500-Cl H 4500-Cl H-00
Total Chlorine Amperometric Titration 4500-Cl D 4500-Cl D-00 D1253-033
Amperometric Titration (low level measurement) 4500-Cl E 4500-Cl E-00
DPD Ferrous Titrimetric 4500-Cl F 4500-Cl F-00
DPD Colorimetric 4500-Cl G 4500-Cl G-00
Iodometric Electrode 4500-Cl I 4500-Cl I-00
Chlorine Dioxide Amperometric Titration 4500-ClO2 C 4500-ClO2 C-00
DPD Method 4500-ClO2 D
Amperometric Titration 4500-ClO2 E 4500-ClO2 E-00
Spectrophotometric 327.0, Revision 1.14
Ozone Indigo Method 4500-O3 B 4500-O3 B-97

(b) Monitoring requirements for systems that do not provide filtration. A public water system that uses a surface water source and does not provide filtration treatment must begin monitoring, as specified in this paragraph (b), beginning December 31, 1990, unless the State has determined that filtration is required in writing pursuant to § 1412(b)(7)(C)(iii), in which case the State may specify alternative monitoring requirements, as appropriate, until filtration is in place. A public water system that uses a ground water source under the direct influence of surface water and does not provide filtration treatment must begin monitoring as specified in this paragraph (b) beginning December 31, 1990, or 6 months after the State determines that the ground water source is under the direct influence of surface water, whichever is later, unless the State has determined that filtration is required in writing pursuant to § 1412(b)(7)(C)(iii), in which case the State may specify alternative monitoring requirements, as appropriate, until filtration is in place.

(1) Fecal coliform or total coliform density measurements as required by § 141.71(a)(1) must be performed on representative source water samples immediately prior to the first or only point of disinfectant application. The system must sample for fecal or total coliforms at the following minimum frequency each week the system serves water to the public:

System size (persons served) Samples/week1
≤500 1
501 to 3,300 2
3,301 to 10,000 3
10,001 to 25,000 4
>25,000 5

Also, one fecal or total coliform density measurement must be made every day the system serves water to the public and the turbidity of the source water exceeds 1 NTU (these samples count towards the weekly coliform sampling requirement) unless the State determines that the system, for logistical reasons outside the system's control, cannot have the sample analyzed within 30 hours of collection.

(2) Turbidity measurements as required by § 141.71(a)(2) must be performed on representative grab samples of source water immediately prior to the first or only point of disinfectant application every four hours (or more frequently) that the system serves water to the public. A public water system may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the State.

(3) The total inactivation ratio for each day that the system is in operation must be determined based on the CT99.9 values in tables 1.1-1.6, 2.1, and 3.1 of this section, as appropriate. The parameters necessary to determine the total inactivation ratio must be monitored as follows:

(i) The temperature of the disinfected water must be measured at least once per day at each residual disinfectant concentration sampling point.

(ii) If the system uses chlorine, the pH of the disinfected water must be measured at least once per day at each chlorine residual disinfectant concentration sampling point.

(iii) The disinfectant contact time(s) (“T”) must be determined for each day during peak hourly flow.

(iv) The residual disinfectant concentration(s) (“C”) of the water before or at the first customer must be measured each day during peak hourly flow.

(v) If a system uses a disinfectant other than chlorine, the system may demonstrate to the State, through the use of a State-approved protocol for on-site disinfection challenge studies or other information satisfactory to the State, that CT99.9 values other than those specified in tables 2.1 and 3.1 in this section other operational parameters are adequate to demonstrate that the system is achieving the minimum inactivation rates required by § 141.72(a)(1).

Table 1.1 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 0.5 °C or Lower1

Residual (mg/l) pH
≤6.0 6.5 7.0 7.5 8.0 8.5 ≤9.0
≤0.4 137 163 195 237 277 329 390
0.6 141 168 200 239 286 342 407
0.8 145 172 205 246 295 354 422
1.0 148 176 210 253 304 365 437
1.2 152 180 215 259 313 376 451
1.4 155 184 221 266 321 387 464
1.6 157 189 226 273 329 397 477
1.8 162 193 231 279 338 407 489
2.0 165 197 236 286 346 417 500
2.2 169 201 242 297 353 426 511
2.4 172 205 247 298 361 435 522
2.6 175 209 252 304 368 444 533
2.8 178 213 257 310 375 452 543
3.0 181 217 261 316 382 460 552

Table 1.2 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 5.0 °C1

Free residual (mg/l) pH
≤6.0 6.5 7.0 7.5 8.0 8.5 ≤9.0
≤0.4 97 117 139 166 198 236 279
0.6 100 120 143 171 204 244 291
0.8 103 122 146 175 210 252 301
1.0 105 125 149 179 216 260 312
1.2 107 127 152 183 221 267 320
1.4 109 130 155 187 227 274 329
1.6 111 132 158 192 232 281 337
1.8 114 135 162 196 238 287 345
2.0 116 138 165 200 243 294 353
2.2 118 140 169 204 248 300 361
2.4 120 143 172 209 253 306 368
2.6 122 146 175 213 258 312 375
2.8 124 148 178 217 263 318 382
3.0 126 151 182 221 268 324 389

Table 1.3 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 10.0 °C1

Free residual (mg/l) pH
≤6.0 6.5 7.0 7.5 8.0 8.5 ≤9.0
≤0.4 73 88 104 125 149 177 209
0.6 75 90 107 128 153 183 218
0.8 78 92 110 131 158 189 226
1.0 79 94 112 134 162 195 234
1.2 80 95 114 137 166 200 240
1.4 82 98 116 140 170 206 247
1.6 83 99 119 144 174 211 253
1.8 86 101 122 147 179 215 259
2.0 87 104 124 150 182 221 265
2.2 89 105 127 153 186 225 271
2.4 90 107 129 157 190 230 276
2.6 92 110 131 160 194 234 281
2.8 93 111 134 163 197 239 287
3.0 95 113 137 166 201 243 292

Table 1.4 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 15.0 °C1

Free residual (mg/l) pH
≤6.0 6.5 7.0 7.5 8.0 8.5 ≤9.0
≤0.4 49 59 70 83 99 118 140
0.6 50 60 72 86 102 122 146
0.8 52 61 73 88 105 126 151
1.0 53 63 75 90 108 130 156
1.2 54 64 76 92 111 134 160
1.4 55 65 78 94 114 137 165
1.6 56 66 79 96 116 141 169
1.8 57 68 81 98 119 144 173
2.0 58 69 83 100 122 147 177
2.2 59 70 85 102 124 150 181
2.4 60 72 86 105 127 153 184
2.6 61 73 88 107 129 156 188
2.8 62 74 89 109 132 159 191
3.0 63 76 91 111 134 162 195

Table 1.5 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 20 °C1

Free residual (mg/l) pH
≤6.0 6.5 7.0 7.5 8.0 8.5 ≤9.0
≤0.4 36 44 52 62 74 89 105
0.6 38 45 54 64 77 92 109
0.8 39 46 55 66 79 95 113
1.0 39 47 56 67 81 98 117
1.2 40 48 57 69 83 100 120
1.4 41 49 58 70 85 103 123
1.6 42 50 59 72 87 105 126
1.8 43 51 61 74 89 108 129
2.0 44 52 62 75 91 110 132
2.2 44 53 63 77 93 113 135
2.4 45 54 65 78 95 115 138
2.6 46 55 66 80 97 117 141
2.8 47 56 67 81 99 119 143
3.0 47 57 68 83 101 122 146

Table 1.6 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Free Chlorine at 25 °C1 and Higher

Free residual (mg/l) pH
≤6.0 6.5 7.0 7.5 8.0 8.5 ≤9.0
≤0.4 24 29 35 42 50 59 70
0.6 25 30 36 43 51 61 73
0.8 26 31 37 44 53 63 75
1.0 26 31 37 45 54 65 78
1.2 27 32 38 46 55 67 80
1.4 27 33 39 47 57 69 82
1.6 28 33 40 48 58 70 84
1.8 29 34 41 49 60 72 86
2.0 29 35 41 50 61 74 88
2.2 30 35 42 51 62 75 90
2.4 30 36 43 52 63 77 92
2.6 31 37 44 53 65 78 94
2.8 31 37 45 54 66 80 96
3.0 32 38 46 55 67 81 97

Table 2.1 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts by Chlorine Dioxide and Ozone1

Temperature
<1 °C 5 °C 10 °C 15 °C 20 °C ≥25 °C
Chlorine dioxide 63 26 23 19 15 11
Ozone 2.9 1.9 1.4 0.95 0.72 0.48

Table 3.1 - CT Values (CT99.9) for 99.9 Percent Inactivation of Giardia Lamblia Cysts By Chloramines1

Temperature
<1 °C 5 °C 10 °C 15 °C 20 °C 25 °C
3,800 2,200 1,850 1,500 1,100 750

(4) The total inactivation ratio must be calculated as follows:

(i) If the system uses only one point of disinfectant application, the system may determine the total inactivation ratio based on either of the following two methods:

(A) One inactivation ratio (CTcalc/CT99.9) is determined before or at the first customer during peak hourly flow and if the CTcalc/CT99.9 ≥1.0, the 99.9 percent Giardia lamblia inactivation requirement has been achieved; or

(B) Successive CTcalc/CT99.9 values, representing sequential inactivation ratios, are determined between the point of disinfectant application and a point before or at the first customer during peak hourly flow. Under this alternative, the following method must be used to calculate the total inactivation ratio:

lamblia inactivation requirement has been achieved.

(ii) If the system uses more than one point of disinfectant application before or at the first customer, the system must determine the CT value of each disinfection sequence immediately prior to the next point of disinfectant application during peak hourly flow. The CTcalc/CT99.9 value of each sequence and

must be calculated using the method in paragraph (b)(4)(i)(B) of this section to determine if the system is in compliance with § 141.72(a).

(iii) Although not required, the total percent inactivation for a system with one or more points of residual disinfectant concentration monitoring may be calculated by solving the following equation:

(5) The residual disinfectant concentration of the water entering the distribution system must be monitored continuously, and the lowest value must be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every 4 hours may be conducted in lieu of continuous monitoring, but for no more than 5 working days following the failure of the equipment, and systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies prescribed below:

System size by population Samples/day1
<500 1
501 to 1,000 2
1,001 to 2,500 3
2,501 to 3,300 4

If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the system must take a grab sample every 4 hours until the residual concentration is equal to or greater than 0.2 mg/l.

(6)

(i) Until March 31, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in § 141.21. Beginning April 1, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in §§ 141.854 through 141.858. The State may allow a public water system which uses both a surface water source or a ground water source under direct influence of surface water, and a ground water source, to take disinfectant residual samples at points other than the total coliform sampling points if the State determines that such points are more representative of treated (disinfected) water quality within the distribution system. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in paragraph (a)(1) of this section, may be measured in lieu of residual disinfectant concentration.

(ii) If the State determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified by paragraph (a)(1) of this section and that the system is providing adequate disinfection in the distribution system, the requirements of paragraph (b)(6)(i) of this section do not apply to that system.

(c) Monitoring requirements for systems using filtration treatment. A public water system that uses a surface water source or a ground water source under the influence of surface water and provides filtration treatment must monitor in accordance with this paragraph (c) beginning June 29, 1993, or when filtration is installed, whichever is later.

(1) Turbidity measurements as required by § 141.73 must be performed on representative samples of the system's filtered water every four hours (or more frequently) that the system serves water to the public. A public water system may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the State. For any systems using slow sand filtration or filtration treatment other than conventional treatment, direct filtration, or diatomaceous earth filtration, the State may reduce the sampling frequency to once per day if it determines that less frequent monitoring is sufficient to indicate effective filtration performance. For systems serving 500 or fewer persons, the State may reduce the turbidity sampling frequency to once per day, regardless of the type of filtration treatment used, if the State determines that less frequent monitoring is sufficient to indicate effective filtration performance.

(2) The residual disinfectant concentration of the water entering the distribution system must be monitored continuously, and the lowest value must be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every 4 hours may be conducted in lieu of continuous monitoring, but for no more than 5 working days following the failure of the equipment, and systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies each day prescribed below:

System size by population Samples/day1
±500 1
501 to 1,000 2
1,001 to 2,500 3
2,501 to 3,300 4

If at any time the residual disinfectant concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the system must take a grab sample every 4 hours until the residual disinfectant concentration is equal to or greater than 0.2 mg/l.

(3)

(i) Until March 31, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in § 141.21. Beginning April 1, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in §§ 141.854 through 141.858. The State may allow a public water system which uses both a surface water source or a ground water source under direct influence of surface water, and a ground water source, to take disinfectant residual samples at points other than the total coliform sampling points if the State determines that such points are more representative of treated (disinfected) water quality within the distribution system. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in paragraph (a)(1) of this section, may be measured in lieu of residual disinfectant concentration.

(ii) If the State determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified by paragraph (a)(1) of this section and that the system is providing adequate disinfection in the distribution system, the requirements of paragraph (c)(3)(i) of this section do not apply to that system.

[54 FR 27527, June 29, 1989, as amended at 59 FR 62470, Dec. 5, 1994; 60 FR 34086, June 29, 1995; 64 FR 67465, Dec. 1, 1999; 67 FR 65252, Oct. 23, 2002; 67 FR 65901, Oct. 29, 2002; 69 FR 38856, June 29, 2004; 72 FR 11247, Mar. 12, 2007; 74 FR 30958, June 29, 2009; 78 FR 10347, Feb. 13, 2013]

§ 141.75 Reporting and recordkeeping requirements.

(a) A public water system that uses a surface water source and does not provide filtration treatment must report monthly to the State the information specified in this paragraph (a) beginning December 31, 1990, unless the State has determined that filtration is required in writing pursuant to section 1412(b)(7)(C)(iii), in which case the State may specify alternative reporting requirements, as appropriate, until filtration is in place. A public water system that uses a ground water source under the direct influence of surface water and does not provide filtration treatment must report monthly to the State the information specified in this paragraph (a) beginning December 31, 1990, or 6 months after the State determines that the ground water source is under the direct influence of surface water, whichever is later, unless the State has determined that filtration is required in writing pursuant to § 1412(b)(7)(C)(iii), in which case the State may specify alternative reporting requirements, as appropriate, until filtration is in place.

(1) Source water quality information must be reported to the State within 10 days after the end of each month the system serves water to the public. Information that must be reported includes:

(i) The cumulative number of months for which results are reported.

(ii) The number of fecal and/or total coliform samples, whichever are analyzed during the month (if a system monitors for both, only fecal coliforms must be reported), the dates of sample collection, and the dates when the turbidity level exceeded 1 NTU.

(iii) The number of samples during the month that had equal to or less than 20/100 ml fecal coliforms and/or equal to or less than 100/100 ml total coliforms, whichever are analyzed.

(iv) The cumulative number of fecal or total coliform samples, whichever are analyzed, during the previous six months the system served water to the public.

(v) The cumulative number of samples that had equal to or less than 20/100 ml fecal coliforms or equal to or less than 100/100 ml total coliforms, whichever are analyzed, during the previous six months the system served water to the public.

(vi) The percentage of samples that had equal to or less than 20/100 ml fecal coliforms or equal to or less than 100/100 ml total coliforms, whichever are analyzed, during the previous six months the system served water to the public.

(vii) The maximum turbidity level measured during the month, the date(s) of occurrence for any measurement(s) which exceeded 5 NTU, and the date(s) the occurrence(s) was reported to the State.

(viii) For the first 12 months of recordkeeping, the dates and cumulative number of events during which the turbidity exceeded 5 NTU, and after one year of recordkeeping for turbidity measurements, the dates and cumulative number of events during which the turbidity exceeded 5 NTU in the previous 12 months the system served water to the public.

(ix) For the first 120 months of recordkeeping, the dates and cumulative number of events during which the turbidity exceeded 5 NTU, and after 10 years of recordkeeping for turbidity measurements, the dates and cumulative number of events during which the turbidity exceeded 5 NTU in the previous 120 months the system served water to the public.

(2) Disinfection information specified in § 141.74(b) must be reported to the State within 10 days after the end of each month the system serves water to the public. Information that must be reported includes:

(i) For each day, the lowest measurement of residual disinfectant concentration in mg/l in water entering the distribution system.

(ii) The date and duration of each period when the residual disinfectant concentration in water entering the distribution system fell below 0.2 mg/l and when the State was notified of the occurrence.

(iii) The daily residual disinfectant concentration(s) (in mg/l) and disinfectant contact time(s) (in minutes) used for calculating the CT value(s).

(iv) If chlorine is used, the daily measurement(s) of pH of disinfected water following each point of chlorine disinfection.

(v) The daily measurement(s) of water temperature in °C following each point of disinfection.

(vi) The daily CTcalc and CTcalc/CT99.9 values for each disinfectant measurement or sequence and the sum of all CTcalc/CT99.9 values ((CTcalc/CT99.9)) before or at the first customer.

(vii) The daily determination of whether disinfection achieves adequate Giardia cyst and virus inactivation, i.e., whether (CTcalc/CT99.9) is at least 1.0 or, where disinfectants other than chlorine are used, other indicator conditions that the State determines are appropriate, are met.

(viii) The following information on the samples taken in the distribution system in conjunction with total coliform monitoring pursuant to § 141.72:

(A) Number of instances where the residual disinfectant concentration is measured;

(B) Number of instances where the residual disinfectant concentration is not measured but heterotrophic bacteria plate count (HPC) is measured;

(C) Number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;

(D) Number of instances where the residual disinfectant concentration is detected and where HPC is >500/ml;

(E) Number of instances where the residual disinfectant concentration is not measured and HPC is >500/ml;

(F) For the current and previous month the system served water to the public, the value of “V” in the following formula:

where:

a = the value in paragraph (a)(2)(viii)(A) of this section,

b = the value in paragraph (a)(2)(viii)(B) of this section,

c = the value in paragraph (a)(2)(viii)(C) of this section,

d = the value in paragraph (a)(2)(viii)(D) of this section, and

e = the value in paragraph (a)(2)(viii)(E) of this section.

(G) If the State determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory under the requisite time and temperature conditions specified by § 141.74(a)(1) and that the system is providing adequate disinfection in the distribution system, the requirements of paragraph (a)(2)(viii) (A)-(F) of this section do not apply to that system.

(ix) A system need not report the data listed in paragraphs (a)(2) (i), and (iii)-(vi) of this section if all data listed in paragraphs (a)(2) (i)-(viii) of this section remain on file at the system, and the State determines that:

(A) The system has submitted to the State all the information required by paragraphs (a)(2) (i)-(viii) of this section for at least 12 months; and

(B) The State has determined that the system is not required to provide filtration treatment.

(3) No later than ten days after the end of each Federal fiscal year (September 30), each system must provide to the State a report which summarizes its compliance with all watershed control program requirements specified in § 141.71(b)(2).

(4) No later than ten days after the end of each Federal fiscal year (September 30), each system must provide to the State a report on the on-site inspection conducted during that year pursuant to § 141.71(b)(3), unless the on-site inspection was conducted by the State. If the inspection was conducted by the State, the State must provide a copy of its report to the public water system.

(5)

(i) Each system, upon discovering that a waterborne disease outbreak potentially attributable to that water system has occurred, must report that occurrence to the State as soon as possible, but no later than by the end of the next business day.

(ii) If at any time the turbidity exceeds 5 NTU, the system must consult with the primacy agency as soon as practical, but no later than 24 hours after the exceedance is known, in accordance with the public notification requirements under § 141.203(b)(3).

(iii) If at any time the residual falls below 0.2 mg/l in the water entering the distribution system, the system must notify the State as soon as possible, but no later than by the end of the next business day. The system also must notify the State by the end of the next business day whether or not the residual was restored to at least 0.2 mg/l within 4 hours.

(b) A public water system that uses a surface water source or a ground water source under the direct influence of surface water and provides filtration treatment must report monthly to the State the information specified in this paragraph (b) beginning June 29, 1993, or when filtration is installed, whichever is later.

(1) Turbidity measurements as required by § 141.74(c)(1) must be reported within 10 days after the end of each month the system serves water to the public. Information that must be reported includes:

(i) The total number of filtered water turbidity measurements taken during the month.

(ii) The number and percentage of filtered water turbidity measurements taken during the month which are less than or equal to the turbidity limits specified in § 141.73 for the filtration technology being used.

(iii) The date and value of any turbidity measurements taken during the month which exceed 5 NTU.

(2) Disinfection information specified in § 141.74(c) must be reported to the State within 10 days after the end of each month the system serves water to the public. Information that must be reported includes:

(i) For each day, the lowest measurement of residual disinfectant concentration in mg/l in water entering the distribution system.

(ii) The date and duration of each period when the residual disinfectant concentration in water entering the distribution system fell below 0.2 mg/l and when the State was notified of the occurrence.

(iii) The following information on the samples taken in the distribution system in conjunction with total coliform monitoring pursuant to § 141.72:

(A) Number of instances where the residual disinfectant concentration is measured;

(B) Number of instances where the residual disinfectant concentration is not measured but heterotrophic bacteria plate count (HPC) is measured;

(C) Number of instances where the residual disinfectant concentration is measured but not detected and no HPC is measured;

(D) Number of instances where no residual disinfectant concentration is detected and where HPC is >500/ml;

(E) Number of instances where the residual disinfectant concentration is not measured and HPC is >500/ml;

(F) For the current and previous month the system serves water to the public, the value of “V” in the following formula:

where:

a = the value in paragraph (b)(2)(iii)(A) of this section,

b = the value in paragraph (b)(2)(iii)(B) of this section,

c = the value in paragraph (b)(2)(iii)(C) of this section,

d = the value in paragraph (b)(2)(iii)(D) of this section, and

e = the value in paragraph (b)(2)(iii)(E) of this section.

(G) If the State determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by a certified laboratory within the requisite time and temperature conditions specified by § 141.74(a)(1) and that the system is providing adequate disinfection in the distribution system, the requirements of paragraph (b)(2)(iii) (A)-(F) of this section do not apply.

(iv) A system need not report the data listed in paragraph (b)(2)(i) of this section if all data listed in paragraphs (b)(2) (i)-(iii) of this section remain on file at the system and the State determines that the system has submitted all the information required by paragraphs (b)(2) (i)-(iii) of this section for at least 12 months.

(3)

(i) Each system, upon discovering that a waterborne disease outbreak potentially attributable to that water system has occurred, must report that occurrence to the State as soon as possible, but no later than by the end of the next business day.

(ii) If at any time the turbidity exceeds 5 NTU, the system must consult with the primacy agency as soon as practical, but no later than 24 hours after the exceedance is known, in accordance with the public notification requirements under § 141.203(b)(3).

(iii) If at any time the residual falls below 0.2 mg/l in the water entering the distribution system, the system must notify the State as soon as possible, but no later than by the end of the next business day. The system also must notify the State by the end of the next business day whether or not the residual was restored to at least 0.2 mg/l within 4 hours.

[54 FR 27527, June 29, 1989, as amended at 65 FR 26022, May 4, 2000; 69 FR 38856, June 29, 2004]

§ 141.76 Recycle provisions.

(a) Applicability. All subpart H systems that employ conventional filtration or direct filtration treatment and that recycle spent filter backwash water, thickener supernatant, or liquids from dewatering processes must meet the requirements in paragraphs (b) through (d) of this section.

(b) Reporting. A system must notify the State in writing by Decemeber 8, 2003, if the system recycles spent filter backwash water, thickener supernatant, or liquids from dewatering processes. This notification must include, at a minimum, the information specified in paragraphs (b)(1) and (2) of this section.

(1) A plant schematic showing the origin of all flows which are recycled (including, but not limited to, spent filter backwash water, thickener supernatant, and liquids from dewatering processes), the hydraulic conveyance used to transport them, and the location where they are re-introduced back into the treatment plant.

(2) Typical recycle flow in gallons per minute (gpm), the highest observed plant flow experienced in the previous year (gpm), design flow for the treatment plant (gpm), and State-approved operating capacity for the plant where the State has made such determinations.

(c) Treatment technique requirement. Any system that recycles spent filter backwash water, thickener supernatant, or liquids from dewatering processes must return these flows through the processes of a system's existing conventional or direct filtration system as defined in § 141.2 or at an alternate location approved by the State by June 8, 2004. If capital improvements are required to modify the recycle location to meet this requirement, all capital improvements must be completed no later than June 8, 2006.

(d) Recordkeeping. The system must collect and retain on file recycle flow information specified in paragraphs (d)(1) through (6) of this section for review and evaluation by the State beginning June 8, 2004.

(1) Copy of the recycle notification and information submitted to the State under paragraph (b) of this section.

(2) List of all recycle flows and the frequency with which they are returned.

(3) Average and maximum backwash flow rate through the filters and the average and maximum duration of the filter backwash process in minutes.

(4) Typical filter run length and a written summary of how filter run length is determined.

(5) The type of treatment provided for the recycle flow.

(6) Data on the physical dimensions of the equalization and/or treatment units, typical and maximum hydraulic loading rates, type of treatment chemicals used and average dose and frequency of use, and frequency at which solids are removed, if applicable.

[66 FR 31103, June 8, 2001]

Subpart I - Control of Lead and Copper
Source:

56 FR 26548, June 7, 1991, unless otherwise noted.

§ 141.80 General requirements.

(a) Applicability and effective dates.

(1) The requirements of this subpart I constitute the national primary drinking water regulations for lead and copper. Unless otherwise indicated, each of the provisions of this subpart applies to community water systems and non-transient, non-community water systems (hereinafter referred to as “water systems” or “systems”).

(2) [Reserved]

(b) Scope. These regulations establish a treatment technique that includes requirements for corrosion control treatment, source water treatment, lead service line replacement, and public education. These requirements are triggered, in some cases, by lead and copper action levels measured in samples collected at consumers' taps.

(c) Lead and copper action levels.

(1) The lead action level is exceeded if the concentration of lead in more than 10 percent of tap water samples collected during any monitoring period conducted in accordance with § 141.86 is greater than 0.015 mg/L (i.e., if the “90th percentile” lead level is greater than 0.015 mg/L).

(2) The copper action level is exceeded if the concentration of copper in more than 10 percent of tap water samples collected during any monitoring period conducted in accordance with § 141.86 is greater than 1.3 mg/L (i.e., if the “90th percentile” copper level is greater than 1.3 mg/L).

(3) The 90th percentile lead and copper levels shall be computed as follows:

(i) The results of all lead or copper samples taken during a monitoring period shall be placed in ascending order from the sample with the lowest concentration to the sample with the highest concentration. Each sampling result shall be assigned a number, ascending by single integers beginning with the number 1 for the sample with the lowest contaminant level. The number assigned to the sample with the highest contaminant level shall be equal to the total number of samples taken.

(ii) The number of samples taken during the monitoring period shall be multiplied by 0.9.

(iii) The contaminant concentration in the numbered sample yielded by the calculation in paragraph (c)(3)(ii) is the 90th percentile contaminant level.

(iv) For water systems serving fewer than 100 people that collect 5 samples per monitoring period, the 90th percentile is computed by taking the average of the highest and second highest concentrations.

(v) For a public water system that has been allowed by the State to collect fewer than five samples in accordance with § 141.86(c), the sample result with the highest concentration is considered the 90th percentile value.

(d) Corrosion control treatment requirements.

(1) All water systems shall install and operate optimal corrosion control treatment as defined in § 141.2.

(2) Any water system that complies with the applicable corrosion control treatment requirements specified by the State under §§ 141.81 and 141.82 shall be deemed in compliance with the treatment requirement contained in paragraph (d)(1) of this section.

(e) Source water treatment requirements. Any system exceeding the lead or copper action level shall implement all applicable source water treatment requirements specified by the State under § 141.83.

(f) Lead service line replacement requirements. Any system exceeding the lead action level after implementation of applicable corrosion control and source water treatment requirements shall complete the lead service line replacement requirements contained in § 141.84.

(g) Public education requirements. Pursuant to § 141.85, all water systems must provide a consumer notice of lead tap water monitoring results to persons served at the sites (taps) that are tested. Any system exceeding the lead action level shall implement the public education requirements.

(h) Monitoring and analytical requirements. Tap water monitoring for lead and copper, monitoring for water quality parameters, source water monitoring for lead and copper, and analyses of the monitoring results under this subpart shall be completed in compliance with §§ 141.86, 141.87, 141.88, and 141.89.

(i) Reporting requirements. Systems shall r