310 CMR, § 22.06

Current through Register 1533, October 25, 2024

Section 22.06 - Inorganic Chemical Maximum Contaminant Levels, Monitoring Requirements and Analytical Methods

(1)Monitoring. A Supplier of Water shall collect samples of water as specified in 310 CMR 22.06(4) and provide for analysis of such samples for inorganic chemical contaminants listed in 310 CMR 22.06(2) consistent with the requirements set forth in 310 CMR 22.06(5) through (9) and methods set forth in 310 CMR 22.06(16).

All analytical results shall be rounded to the same number of significant figures as the applicable MCL or SMCL.

(2)Inorganic Maximum Contaminant Levels (MCLs). The Maximum Contaminant Levels for inorganic contaminants specified in 310 CMR 22.06(2)(b) through (g) and (k) through (q) apply to Community Water Systems and Non-transient Non-community Water Systems. The Maximum Contaminant Level specified in 310 CMR 22.06(2)(a) only applies to Community Water Systems. The Maximum Contaminant Levels specified in 310 CMR 22.06(2)(h) through (j) apply to Community, Non-transient Non-community, and Transient Non-community Water Systems. The Maximum Contaminant Level for arsenic is 0.05 milligrams per liter for Community Water Systems and Non-transient Non-community Water Systems until January 23, 2006.

MAXIMUM CONTAMINANT LEVELS FOR INORGANIC CHEMICALS

Contaminant	MCL (mg/l)
(a) Fluoride (C)	4.0
(b) Asbestos (C, NTNC)	7 Million Fibers/liter (longer than 10 µm)
(c) Arsenic (C,NTNC)	0.010
(d) Barium (C,NTNC)	2
(e) Cadmium (C,NTNC)	0.005
(f) Chromium (C,NTNC)	0.1
(g) Mercury (C,NTNC)	0.002
(h) Nitrate (C,NTNC,TNC)	10 (as Nitrogen)
(i) Nitrite (C,NTNC,TNC)	1 (as Nitrogen)
(j) Total Nitrate & Nitrite (C,NTNC,TNC)	10 (as Nitrogen)
(k) Selenium (C,NTNC)	0.05
(l) Antimony (C,NTNC)	0.006
(m) Beryllium (C,NTNC)	0.004
(n) Cyanide (as free Cyanide) (C,NTNC)	0.2
(o) Nickel (C,NTNC)	[Reserved] (Under review)
(p) Thallium (C,NTNC)	0.002
(q) Perchlorate (C,NTNC)	0.0020¹

C = Community Water Systems; NTNC = Non-transient Non-community Water Systems;

TNC = Transient Non-community Water Systems

¹ The Department will review and revise as necessary the perchlorate MCL within six years of its promulgation, taking into account new data on health effects, sources and occurrence, Treatment Techniques and associated issues, analytical feasibility and any other relevant information.

(3)Inorganic Chemicals (IOC). Sampling and Analytical Requirements: Community Water Systems and Non-transient Non-community Water Systems shall conduct monitoring to determine compliance with the Maximum Contaminant Levels specified in 310 CMR 22.06(2) in accordance with 310 CMR 22.06. Transient, Non-community Water Systems shall conduct monitoring to determine compliance with the MCLs for nitrate, nitrite and total nitrate in 310 CMR 22.06(2)(h) through (j) (as appropriate) in accordance with 310 CMR 22.06.

(4)Sampling Protocol. Monitoring shall be as follows:

(a)Ground Water Sampling Points. Groundwater systems shall take one sample at every entry point to the Distribution System which is representative of each well after treatment (Sampling Point) beginning in the Compliance Period starting January 1, 1993. 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.

(b)Surface Water Sampling Points. Surface water systems (Note: or purposes of 310 CMR 22.06(4)(b), Surface Water systems include systems with a combination of surface and ground sources) 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 ( Sampling Point) beginning in the Compliance Period beginning January 1, 1993. 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.

(c)Multiple Sources. 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).

(d)Composite Sampling. The total number of samples which must be analyzed may be reduced by compositing samples. 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 1/5 of the MCL and none of the samples to be composited are representative of multiple sources. Compositing of samples must be approved by the Department and must be done in the laboratory. Compositing of source with previous detects is not allowed, unless otherwise authorized by the Department.

1. If the concentration in the composite sample is greater than or equal to 1/5 of the MCL of any inorganic chemical, then a follow-up sample must be analyzed within 14 days from each Sampling Point included in the composite. These samples must be analyzed for the contaminants that exceeded 1/5 of the MCL in the composite sample. Detection limits for each analytical method and MCL 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 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	0.2 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, Selective Electrode ^3,⁴	0.05
Distillation, Amenable, Spectrophotometric ⁴	0.02
UV, Distillation, Spectrophotometric¹¹	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	Reserved
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
Perchlorate	0.0020	Ion Chromatography⁹	0.0010¹⁰
LC/MS or LC/MS/MS	0.0010
IC/MS or IC/MS/MS	0.0010
Selenium	0.05	Atomic Absorption; furnace	0.002
Atomic Absorption: gaseous hydride	0.002
Sodium	See 310 CMR 22.06A
Thallium	0.002	Atomic Absorption; furnace	0.001
Atomic Absorption; platform	0.0007⁵
ICP-Mass Spectrometry	0.0003

¹ MFL = million fibers per liter >10 µm.

² Using a 2X preconcentration step as noted in Method 200.7. Lower MDLs may be achieved when using a 4X preconcentration.

³ Screening methods for total cyanides.

⁴ Measures "free" cyanides when distillation, digestion, or ligand exchange is omitted.

⁵ Lower MDLs are reported using stabilized temperature graphite furnace atomic absorption.

⁶ The MCL for arsenic is effective January 23, 2006. Until then, the MCL is 0.05 mg/l.

⁷ The MDL reported for EPA method 200.9 (Atomic Absorption; Platform---Stabilized Temperature) was determined using a 2x concentration step during sample digestion. The MDL determined for samples analyzed using direct analyses (i.e., no sample digestion) will be higher. Using multiple deposition, EPA 200.9 is capable of obtaining MDL of 0.0001 mg/l.

⁸ Using selective ion monitoring, EPA Method 200.8 (ICP-MS) is capable of obtaining a MDL of 0.0001 mg/l.

⁹ Analysis must be conducted using EPA Method 314.0, revision 1.0, November 1999 as modified to achieve the stated detection limit or EPA Method 314.1.

¹⁰ Minimum Reporting Level (MRL). EPA Method 314.0 is capable of obtaining a MDL of less than 0.0010 mg/l.

¹¹ Measures total cyanides when UV-digestor is used, and "free" cyanides when UV-digestor is bypassed.

2. If the population served by the system is >3,300 persons, then compositing may only be permitted at Sampling Points within a single system. In systems serving <3,300 persons, compositing among different systems may be allowed with the approval of the Department, provided the five-sample limit is maintained.

3. If duplicates of the original sample taken from each Sampling Point used in the composite are available, the system may use these instead of resampling. The duplicates must be analyzed and the results reported to the Department within 14 days after completion of the composite analyses or before the holding time for the control sample is exceeded, whichever is sooner.

(e)Frequency Requirements for IOC Monitoring. The frequency of monitoring for asbestos shall be in accordance with 310 CMR 22.06(5); the frequency of monitoring for antimony, arsenic, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium and thallium shall be in accordance with 310 CMR 22.06(6); the frequency of monitoring for nitrate shall be in accordance with 310 CMR 22.06(7); the frequency of monitoring for nitrite shall be in accordance with 310 CMR 22.06(8); and the frequency of monitoring for perchlorate shall be in accordance with 310 CMR 22.06(9).

(f)Consecutive System Monitoring. Public Water Systems that obtain water from another Public Water System are exempt from conducting compliance monitoring for the purchased portion of the system for the inorganic chemicals under 310 CMR 22.06, provided that the system from which the water is obtained has conducted the analyses required under 310 CMR 22.06, unless otherwise specified by the Department. These systems are not exempt from 310 CMR 22.06(5) asbestos sampling.

(5)Asbestos Sampling Frequency. The frequency of monitoring conducted to determine compliance with the Maximum Contaminant Level for asbestos specified in 310 CMR 22.06(2) shall be conducted as follows:

(a)Initial Sampling Frequency. 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 as specified in 310 CMR 22.06(5)(e) through (g).

(b)Sampling During Waiver. 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 Department for a waiver of the monitoring requirement in 310 CMR 22.06(5)(a). If the Department grants the waiver, the system will be required to monitor pursuant to 310 CMR 22.06(5)(d).

(c)Basis of an Asbestos Waiver. The granting of a waiver will be based on a consideration of the following factors:

1. Potential asbestos contamination of the water source; and

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

(d)Effect of an Asbestos Waiver. 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 310 CMR 22.06(5)(a).

(e)Distribution System Sampling Criteria for Asbestos. A system vulnerable to asbestos contamination due solely to corrosion of asbestos-cement pipe shall take at a minimum one sample at a tap approved by the Department. This tap location must be served by asbestos-cement pipe and under conditions where asbestos contamination is most likely to occur. Additional sample locations (taps) may be required if in the Department's opinion the use of asbestos-cement is extensive and contamination is likely to occur in several areas of the system.

(f)Source Water Sampling Criteria for Asbestos. A system vulnerable to asbestos contamination due solely to source water shall monitor in accordance with the provisions of 310 CMR 22.06(2) and (4).

(g)Combined Asbestos Vulnerability. A system vulnerable to asbestos contamination due both to its source water supply and corrosion of asbestos-cement pipe shall monitor in accordance with 310 CMR 22.06(5)(e) and (f).

(h)Exceeding the Asbestos MCL. A system which exceeds the Maximum Contaminant Levels as defined by 310 CMR 22.06(2) shall report to the Department within seven days and shall monitor quarterly beginning in the following quarter.

(i)Average Exceeding MCL. When the average of four analyses made pursuant to 310 CMR 22.06(5)(h), 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 report to the Department pursuant to 310 CMR 22.15 and give public notice to the public pursuant to 310 CMR 22.16. Monitoring after public notification shall be at a frequency designated by the Department and shall continue until the Maximum Contaminant Level has not been exceeded in two successive samples or until a monitoring schedule as condition to variance, exemption or enforcement action shall become effective.

(j)Asbestos Reliably & Consistently below the MCL. The quarterly monitoring requirement may be decreased to the frequency specified in 310 CMR 22.06(5)(a) provided the Department has determined that the system is reliably and consistently below the Maximum Contaminant Level and a groundwater system has taken a minimum of two quarterly samples and a surface (or combined surface/ground) water system has taken a minimum of four quarterly samples.

(k)Grandfathered Asbestos Data. If monitoring data collected after January 1, 1990 are generally consistent with the requirements of 310 CMR 22.06(5), the data may be used with the Department's approval, to satisfy the monitoring requirement for the Initial Compliance Period beginning January 1, 1993.

(6)Sampling Frequency for IOCs. The frequency of monitoring conducted to determine compliance with the Maximum Contaminant Levels in 310 CMR 22.06(2) for antimony, arsenic, beryllium, barium, cadmium, chromium, cyanide, fluoride, mercury, nickel, selenium and thallium shall be as follows:

(a)IOCs Sampling Frequency. Groundwater systems shall take one sample at each Sampling Point once every three years. Surface Water systems (or combined surface/ground) shall take one sample annually at each Sampling Point.

(b)IOCs Sampling Waiver. The system may apply to the Department for a waiver from the monitoring frequencies specified in 310 CMR 22.06(6)(a).

(c)IOC Sampling During a Waiver. 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).

(d)Basis of an IOC Waiver & Grandfathered Data. A waiver may be granted by the Department provided the Surface Water systems have monitored annually for at least three years and groundwater systems have conducted a minimum of three rounds of monitoring. (Analytical monitoring results must have been representative of all sources at the time of sampling.) 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.

(e)Basis of the IOC Sampling Frequency During a Waiver. The granting of a waiver by the Department will be based on the following:

1. Reported concentrations from all previous monitoring;

2. The degree of variation in reported concentrations; and

3. 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.

(f)Effect of an IOC Waiver. A Supplier of Water must have received a written approval from the Department which shall set forth the basis for the determination. The determination may be initiated by the Department or upon an application by the Public Water System. The Public Water System shall specify the basis for its request. The Department may revise its determination of the appropriate monitoring frequency, if the system submits new monitoring data or when other data relevant to the system's appropriate monitoring frequency become available.

(g)Exceeding an IOC MCL. Systems which exceed a Maximum Contaminant Levels as defined by 310 CMR 22.06(2) shall report to the Department within seven days and shall monitor quarterly beginning in the following quarter.

(h)Average Exceeding MCL. When the average of four analyses made pursuant to 310 CMR 22.06(6)(g), 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 report to the Department pursuant to 310 CMR 22.15 and give public notice to the public pursuant to 310 CMR 22.16. Monitoring after public notification shall be at a frequency designated by the Department and shall continue until the Maximum Contaminant Level has not been exceeded in two successive samples or until a monitoring schedule as condition to variance, exemption or enforcement action shall become effective.

(i)IOCs Reliably & Consistently below the MCL. If the system is reliably and consistently below the Maximum Contaminant Level, the quarterly monitoring requirement may be decreased with the Department's approval to the frequencies specified in 310 CMR 22.06(6)(a). Systems requesting this decrease must have taken at a minimum two quarterly samples for a groundwater system and four quarterly samples for a Surface Water system.

(j) All new Public Water 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 as specified by the Department. The system must also comply with the initial sampling frequencies specified by the Department to ensure a system can demonstrate compliance with the MCL. Routine and increased monitoring frequencies shall be conducted in accordance with the requirements in 310 CMR 22.06(6).

(7)Sampling Frequency for Nitrate. All Public Water Systems (Community, Non-transient Non-community, and Transient Non-community Water Systems) shall monitor to determine compliance with the Maximum Contaminant Level for nitrate specified in 310 CMR 22.06(2).

(a)Initial Nitrate Sampling. Community and Non-transient Non-community Water Systems served by groundwater source shall monitor annually beginning January 1, 1993; systems served by Surface Water shall monitor quarterly beginning January 1, 1993.

(b)Transient Non-community Nitrate Sampling Frequency. Each Transient Non-community Water System shall monitor annually beginning January 1, 1993.

(c)Ground Water Repeat Nitrate Sampling Frequency. For all Public 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% the MCL. A groundwater system may reduce the sampling frequency to annually with the Department's approval, after four consecutive quarterly samples are reliably and consistently less than the MCL.

(d)Surface Water Repeat Nitrate Sampling Frequency. All Public Water Systems with Surface Water Sources may reduce the sampling frequency to annually with the Department's approval, if all analytical results from four consecutive quarters are <50% of the MCL. A Surface Water system shall return to quarterly monitoring if any one sample is $50% of the MCL.

(e)Scheduling Annual Nitrate Repeat Samples. After the initial round of quarterly sampling is completed, all Public Water Systems which are monitoring quarterly because the concentration of any one sample was >50% of the MCL shall take subsequent annual samples during the quarter(s) which previously resulted in the highest analytical result.

(8)Sampling Frequency for Nitrite. All Public Water Systems (Community, Non-transient Non-community, and Transient Non-community Water Systems) shall monitor to determine compliance with the Maximum Contaminant Level for nitrite in 310 CMR 22.06(2).

(a)Initial Nitrite Sampling. 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.

(b)Under the Nitrite Trigger Level. After the initial sample, systems where an analytical result for nitrite is <50% of the MCL shall monitor at the frequency specified by the Department.

(c)Above the Nitrite Trigger Level. 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% of the MCL. With the Department's approval, a system may reduce the sampling frequency to annually if the system is reliably and consistently less than the MCL.

(d)Scheduling of Annual Nitrite Repeat Samples. Systems which are monitoring annually shall take each subsequent sample during the quarter(s) which previously resulted in the highest analytical result.

(9)Sampling Frequency for Perchlorate.

(a)Initial Monitoring. Community and Non-transient Non-community systems shall complete initial monitoring for perchlorate as specified in 310 CMR 22.06(9)(a).

1. Effective January 1, 2007, for systems served by groundwater, perchlorate shall be monitored twice, once during the month of April and once during the month of September.

2. Effective January 1, 2007, for systems served by surface water, perchlorate shall be monitored for four consecutive quarters.

(b)Grandfathered Perchlorate Data. If the perchlorate monitoring data collected by a Public Water System after January 1, 2004 is consistent with the requirements of 310 CMR 22.06(9), such data may be used with the Department's approval to satisfy the initial monitoring requirements specified in 310 CMR 22.06(9)(a).

(c)Exceeding the Perchlorate MCL. A Public Water System that exceeds the Maximum Contaminant Level (MCL) for perchlorate in 310 CMR 22.06(2) shall follow the reporting and confirmation procedures in 310 CMR 22.06(10)(c).

(d)Repeat Perchlorate Sampling Frequency. If, after completing the initial monitoring required in 310 CMR 22.06(9)(a), no perchlorate is detected, a Public Water System may thereafter reduce the sampling frequency to once per year.

(e)Exceeding the Perchlorate Trigger Level. The repeat monitoring frequency for any Public Water System shall be on a quarterly basis for at least one year following any one sample in which the concentration is > 0.0010 mg/L (unqualified). With the Department's approval, a system may reduce the sampling frequency to once per year, provided the monitoring for perchlorate done by the system is Reliably and Consistently below the MCL.

(f)Eligibility for a Waiver. A Public Water System may apply for a waiver from the monitoring requirements for perchlorate specified in 310 CMR 22.06(9) in accordance with the IOC waiver provisions in 310 CMR 22.06(6)(b) through (f).

(g) The Department may, on a case-by-case basis, require a Public Water System to monitor for perchlorate more frequently than otherwise provided in 310 CMR 22.06(9)(b) through (f).

(10)Confirmation Sampling.

(a)Deadline for IOCs Confirmation Samples. 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, one additional sample shall be collected as soon as possible after the initial sample was taken (but not to exceed two weeks) at the same Sampling Point.

(b)Deadline for Nitrate & Nitrite Confirmation Samples. 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 and shall report to the Department within seven days. Systems unable to comply with the 24-hour sampling requirement must immediately notify the consumers served by the area served by the Public Water System in accordance with 310 CMR 22.16. Systems exercising this option must take and analyze a confirmation sample within two weeks of notification of the analytical results of the first sample.

(c)Deadline for Perchlorate Confirmation Samples. Whenever the perchlorate sampling results indicate an exceedance of the Maximum Contaminant Level, the system shall take a confirmation sample using EPA Method 331.0 or EPA Method 332.0 in accordance with 310 CMR 22.06(10)(c)1. and 2. within 24 hours of the system's receipt of written notification of the analytical results. For the purposes of 310 CMR 22.06(10)(c), written notification of the analytical results means notification by email, fax, or letter. The system shall report the initial sample result that exceeded the MCL to the Department within seven days. Systems that are unable to take a confirmation sample within 24 hours of the system's receipt of written notification of the analytical results, shall immediately contact the Department for further direction. When taking a confirmation sample as required by 310 CMR 22.06(10)(c):

1. The system shall obtain an analysis and written notification turnaround time for the confirmation sample of no more than three days.

2. The system shall report the confirmation sample results to the Department within three days of the system's receipt of the written notification of the analytical results.

(d)Compliance Calculations & Confirmation Samples. 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 310 CMR 22.06(13). Obvious sampling errors may be deleted with the approval of the Department.

(11)Increased Sampling Frequency. The Department may require more frequent monitoring than specified in 310 CMR 22.06(5) through (9) or may require confirmation samples for positive and negative results at its discretion.

(12)PWS Request for Increased Sampling Frequency. Systems may apply to the Department to conduct more frequent monitoring than the minimum monitoring frequencies specified in 310 CMR 22.06.

(13)Compliance Calculations. Compliance with the Maximum Contaminant Levels set out in 310 CMR 22.06(2) 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.

(a)Sampling Frequencies Greater than Annual. For systems monitoring more than once per year, compliance with the MCL, with the exception of nitrate, nitrite and perchlorate, is determined by a Running Annual Average at each Sampling Point.

(b)Sampling Frequencies of Annual or Less. Each Supplier of Water monitoring annually or less frequently whose sample result exceeds an MCL, with the exception of nitrate, nitrite and perchlorate, must begin quarterly sampling. The system will not be considered in violation of the MCL until it has completed one year of quarterly sampling.

(c) 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.

(d) If a Supplier of Water fails to collect the required number of samples, compliance (average concentration) will be based on the total number of samples collected.

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

(f)Compliance Calculations for Nitrate & Nitrite. Compliance with the Maximum Contaminant Levels for nitrate and nitrite is determined based on one sample if the levels of these contaminants are below the MCLs. If the level of nitrate or nitrite exceeds the MCL in the initial sample, a confirmation sample is required in accordance with 310 CMR 22.06(10)(b) and (d), and compliance shall be determined based on the average of the initial and confirmation samples.

(g)Compliance Calculations for Perchlorate. Compliance with the Maximum Contaminant Level for perchlorate is determined based on one sample if the level is below the MCL. If the level of perchlorate exceeds the MCL in the initial sample a confirmation sample is required in accordance with 310 CMR 22.06(10)(c) and (d), and compliance shall be determined based on the average of the initial and the confirmation sample. The Department may allow or require additional sampling.

(h)Average Exceeding Nitrate, Nitrite and Perchlorate MCL. When the average of analyses made pursuant to 310 CMR 22.06(7) through (9), (10)(b) and (c), 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 report to the Department pursuant to 310 CMR 22.15 and give public notice pursuant to 310 CMR 22.16. Monitoring after public notification shall be at a frequency designated by the Department.

(i) Arsenic sampling results shall be reported to the nearest 0.001 mg/l.

(14)Sampling Schedules: Each Public Water System shall monitor at the time designated by the Department during each Compliance Period.

(15)Reporting MCL Violation: A system which exceeds the MCL listed in 310 CMR 22.06(2) and is out of compliance shall report the exceedance to the Department within seven days.

(16)Analytical and Sampling Methods for Inorganics:

(a)Analytical Methods for IOCs: Analysis for the listed inorganic contaminants shall be conducted using the following methods:

INORGANIC CONTAMINANTS ANALYTICAL METHODS Reference (Method Number)

Contaminant	Methodology¹¹	EPA	ASTM³	SM⁴	SM Online²³	Other
Antimony	Atomic Absorption:	3113B	3113 B-99
Furnace
Atomic Absorption:	²200.9
platform
ICP-Mass Spectrometry	²200.8
Hydride-Atomic Absorption	D-3697-92, 02
Arsenic¹²	Atomic Absorption: Furnace	D2972-97C, 03C	3113B	3113 B-99
Atomic Absorption; Hydride	D-2972-97, 03B	3114B	3114 B-97
Inductively Coupled Plasma¹³	²200.7	3120B⁵	3120 B-99
ICP-Mass Spectrometry	²200.8
Atomic Absorption; Platform	²200.9
Differential Pulse Anodic
Stripping Voltametry	Method 1001¹⁶
Asbestos	Transmission Electron
Microscopy	⁹100.1
Transmission Electron	¹⁰100.2
Microscopy
Barium	Atomic Absorption; Furnace	3113B	3113B-99
Atomic Absorption; Direct	3111D	3111D-99
Inductively Coupled Plasma	²200.7	3120B	3120B-99
ICP-Mass Spectrometry	²200.8
Beryllium	Atomic Absorption; Furnace	D3645-97, 03B	3113B	3113B-99
Atomic Absorption; Platform	²200.9
Inductively Coupled Plasma	²200.7	3120B	3120B-99
ICP-Mass Spectrometry	²200.8
Cadmium	Atomic absorption; Furnace	3113B	3113B-99
Inductively-coupled Plasma	²200.7
ICP-Mass Spectrometry	²200.8
Atomic Absorption; Platform	²200.9
Chromium	Atomic absorption; Furnace	3113B	3113B-99
Inductively Coupled Plasma	²200.7	3120B	3120B-99
ICP-Mass Spectrometry	²200.8
Atomic Absorption; Platform	²200.9
Cyanide	Manual Distillation	D2036-98A	4500-CN^-C
Manual Distillation followed by: Spectrophotometric,
Amenable	D2036-98B	4500-C^-NG	4500-CN ^-G-99
Manual Distillation followed by Spectrophotometric,
Manual	D2036-98A	4500-CN^-E	4500-CN^-E-99	I-3300-85⁵
Spectrophotometric, Semi-automated	⁶335.4
Selective Electrode UV, Distillation, Spectrophotmetric Micro	4500-CN^-F	4500-CN^-F-99
Distillation, Flow Injection Spectrophotometric	Kelada-01¹⁸ QuikChem10-204-00-1-X¹⁹
Ligand Exchange and
Amperometry²²	D6888-04	OIA-1677-DW²¹
Mercury	Manual cold vapor	²245.1	D3223-97,02	3112B	3112B-99
Automated cold vapor	¹245.2
ICP-Mass Spectrometry	²200.8
Nickel	Atomic Absorption: Furnace	3113B	3113B-99
Atomic Absorption: Platform	²200.9
Atomic Absorption Direct	3111B	3113B-99
Inductively Coupled Plasma	²200.7	3120B	3120-99
ICP-Mass Spectrometry	²200.8
Nitrate	Manual cadmium reduction	D3867-90B	4500-NO₃^-E	4500-NO₃^-E-00
Automated cadmium reduction	⁶353.2	D3867-90A	4500-NO₃^-F	4500-NO₃^-F-00
Ion selective electrode	4500-NO₃^-D	4500-NO₃^-D-0	601⁷
Ion chromatography	⁶300.0	D4327-97,03	4110B	4110B-00	B-1011⁸
²⁰300.1
Capillary Ion Electrophoresis	D6508-00, Rev.2²⁴
Nitrite	Spectrophotometric	4500-NO₂^-B	4500- NO₂^-B-00
Automated cadmium reduction	⁶353.2	D3867-90A	4500-NO₃^-F	4500-NO₃^-F-00
Manual cadmium reduction	D3867-90B	4500-NO₃^-E	4500-NO₃^-E-00
Ion chromatography	⁶300.0	D4327-97,03	4110B	4110B-00	B-1011⁸
²⁰300.1
Capillary Ion Electrophoresis	D6508-00, Rev.2²⁴
Perchlorate	Ion chromatography	¹⁴314.0
¹⁵314.1
LC/MS or LC/MS/MS	¹⁶331
IC/MS or IC/MS/MS	¹⁷332
Selenium	Hydride-Atomic absorption;	D3859-98,03A	3114B	3114B-97
Atomic Absorption: Furnace	D3859-98,03B	3113B	3113B-99
ICP-Mass Spectrometry	²200.8
Atomic Absorption; Platform	²200.9
Thallium	Atomic absorption; Platform	²200.9
ICP-Mass Spectrometry	²200.8

The procedures shall be done in accordance with the documents listed below. The incorporation by reference of the following documents listed in footnotes 1-11 and 15 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 documents may be obtained from the sources listed below. Information regarding obtaining these documents can be obtained from the Safe Drinking Water Hotline at 900-426-4791. Documents may be inspected at EPA's Drinking Water Docket, 401 M Street, SW., Washington, DC 20460 (Telephone 202-260-3027); or at the Office of Federal Register, 800 North Capital Street, NW., Suite 700, Washington, DC.

¹Methods of Chemical Analysis of Water and Wastes, EPA-600/4-79-020, March 1983. Available at NTIS, PB84-128677.

²Methods for the Determination of Metals in Environmental Samples - Supplement I, EPA-600/R-94/111 May 1994. Available at NTIS, PB 95-125472.

³ Annual Book of ASTM Standards, 1994 , 1996, or 1999 Vols. 11.01 and 11.02, American Society for Testing and Materials. The previous versions of D1688-95A, D1688-95C (copper), D3559-95D (lead), D1293-95 (pH), D1125-95A, (conductivity) and D859-94 (silica) are also approved. These previous versions D1688-90A, C; D3559-90D, D1293-84, D1125-91A and D859-88, respectively are located in the Annual Book of ASTM Standards, 1994, Vols. 11.01. Copies may be obtained from the American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428.

⁴ 18^th, 19^th, and 20^th edition of Standard Methods for the Examination of Water and Wastewater, 18^th (1982), 19^th (1995), and 20^th (1998) editions, American Public Health Association; either edition may be used. Copies may be obtained from the American Public Health Association, 1015 Fifteenth Street NW, Washington, DC 20005. The cited methods published in any of these three editions may be used, except that the versions of 3111B, 3111D, 3113B and 3114B in the 20^th edition may not be used.

⁵ Method I-2601-90, Methods for Analysis by the U.S. Geological Survey National Water Quality Laboratory - Determination of Inorganic and Organic Constituents in Water and Fluvial Sediments, Open File Report 93-125, 1993; For Methods I-1030-85; I-1601-85; I-1700-85; I-2598-85, I-2700-85; and I-3300-85 See Techniques of Water Resources Investigation of the U.S. Geological Survey, Book 5, Chapter A-1, 3^rd edition, 1989; Available from Information Services, U.S. Geological Survey, Federal Center, Box 25286, Denver, CO 80225-0425.

⁶Methods for the Determination of Inorganic Substances in Environmental Samples, EPA 600/R-93/100, August 1993. Available at NTIS, PB94-120821.

⁷ The procedure shall be done in accordance with Technical Bulletin 601 Standard Method of Test for Nitrate in Drinking Water, July 1994, PN 221890-001, Analytical Technology, Inc. Copies may be obtained from ATI Orion, 529 Main Street, Boston, MA 02129.

⁸ Method B-1011, Standard Method of Test for Nitrate in Drinking Water, July 1994, PN 221890-001, Analytical Technology, Inc. Copies may be obtained from ATI Orion, 529 Main Street, Boston, MA 02129.

⁹ Method 100.1, Analytical Methods for Determination of Asbestos Fibers in Water, EPA/600/4-83/043, September 1983, Available at NTIS, PB83-206471.

¹⁰ Method 100.2, Determination of Asbestos Structures Over 10 µm in Length in Drinking Water, EPA/600/R-94/134, June 1994. Available at NTIS, PB94-201902.

¹¹ Because MDLs reported in EPA Methods 200.7 and 200.9 were determined using a 2X preconcentration step during sample digestion, MDLs determined when samples are analyzed by direct analysis (i.e., no sample digestion) will be higher. For direct analysis of cadmium and arsenic by Method 200.7, and arsenic by Method 3120B sample preconcentration using pneumatic nebulization may be required to achieve lower detection limits. Preconcentration may also be required for direct analysis of antimony, lead, and thallium by Method 200.9; antimony and lead by Method 3113B; and lead by Method D3559-90D unless multiple infurnace depositions are made.

¹² If ultrasonic nebulization is used in the determination of arsenic by Method 200.8 the arsenic must be in the pentavalent state to provide uniform signal response. For direct analysis of arsenic with the Method 200.8 using ultrasonic nebulization, samples and standards must contain 1 mg/L of sodium hypochlorite.

¹³ [Deleted].

¹⁴ Revision 1.0, November, 1999, Determination of Perchlorate in Drinking Water Using Ion Chromatography as modified to achieve performance requirements in 310 CMR 22.06(4).

¹⁵ EPA Method 314.1: Determination of Perchlorate in Drinking Water Using Inline Column Concentration/Matrix Elimination Ion Chromatography with Suppressed Conductivity Detection.

¹⁶ EPA Method 331.0: Determination of Perchlorate in Drinking Water by Liquid Chromatography Electrospray Ionization Mass Spectrometry.

¹⁷ EPA Method 332.0: Determination of Perchlorate in Drinking Water Using Ion Chromatography with Suppressed Conductivity and Electrospray Ionization Mass Spectrometry.

¹⁸ The description for the Kelada-01 Method, Kelada Automated Test Methods for Total Cyanide, Acid Dissociable Cyanide, and Thiocyanate, Revision 1.2, August 2001, EPA #821-B-01-009 for cyanide is available from the National Technical Information Service (NTIS), PB 2001-108275, 5285 Port Royal Road, Springfield, VA 22161. The toll-free telephone number is 800-553-6847. Note: A 450-W UV lamp may be used in this method instead of the 550-W lamp specified if it provides performance within the quality control (QC) acceptance criteria of the method in a given instrument. Similarity, modified flow cell configurations and flow conditions may be used in the method, provided that the QC acceptance criteria are met.

¹⁹ The description for the QuikChem Method 10-204-00-1-X, Digestion and distillation of total cyanide in drinking and wastewaters using MICRO DIST and determination of cyanide by flow injection analysis, "Revision 2.1, November 30, 2000, for cyanide is available from Lachat Instruments, 6645 W. Mill Rd., Milwaukee, WI 53218. Telephone: 414-358-4200.

²⁰Methods for the Determination of Organic and Inorganic Compounds in Drinking Water, Vol.1, EPA 815-R-00-014, August 2000. Available at NTIS, PB2000-106981.

²¹ Method OIA -1677, DW Available Cyanide by Flow Injection, Ligand Exchange, and Amperometry, January 2004. EPA-821-R-04-001, Available from ALPKEM, A Division of OL Analytical, P.O. Box 9010, College Station, TX 77842-9010.

²² Sulfide levels below those detected using lead acetate paper may produce positive method interferences. Test samples using a more sensitive sulfide method to determine if a sulfide interference is present, and treat samples accordingly.

²³ Standard Methods Online are available at http://www.standardmethods.org . The year in which each method was approved by the Standards Methods Committee is designated by the last two digits in the method number. The methods listed are the only online versions that may be used.

²⁴ Method D6508, Rev.2, Test Method for Determination of Dissolved Inorganic Anions in Aqueous Matrices Using Capillary Ion Electrophoresis and Chromate Electrolyte.

(b)Analytical Methods for Fluoride: Analyses for fluoride shall be conducted using the following methods:

Reference (Method Number)
Methodology	EPA	ASTM¹	SM²	SM Online⁸	Other
Ion Chromatography	300.05	D4327-97	4110B	4110B-00-
Manual Distillation; Colorimetric SPADNS	300.16	4500F-B,D	4500F-B,D-97
Manual Electrode	D1179-93,99B	4500F-C	4500F-C-97
Automated Alizarin fluorine blue -lanthanum with distillation (complexone)	4500F-E	129-71W³
Automated ion selective electrode	380-75WE⁴
Capillary Ion Electrophoresis	D6508, Rev. 2⁷

¹ Annual Book of ASTM Standards, part 31 Water. American Society for Testing and Materials, 1916 Race Street, Philadelphia, Pennsylvania 19103.

²Standard Methods for the Examination of Water and Wastewater, 18^th, 19^th, and 20^th edition, American Public Health Association, American Water Works Association, Water Pollution Control Federation, 1992, 1995, and 1998.

³Fluoride in Water and Wastewater, Industrial Method # 129-71W. Technicon Industrial Systems. December 1972. Copies may be obtained from Bran & Luebbe, 1025 Busch Parkway, Buffalo Grove, IL 60089.

⁴Fluoride in Water and Wastewater, Technicon Industrial Systems. February 1976. Copies may be obtained from Bran & Luebbe, 1025 Busch Parkway, Buffalo Grove, IL 60089.

⁵Methods for the Determination of Inorganic Substances in Environmental Samples, EPA-600/R-93/100, August 1993. Available at NTIS, PB94-120821.

⁶Methods for the Determination of Organic and Inorganic Compounds in Drinking Water, Vol.1, EPA 815-R-00-014, August 2000, Available at NTIS, PB2000-106981.

⁷ Method 6508, Rev.2, Test Method for Determination of Dissolved Inorganic Anions in Aqueous Matrices Using Capillary Ion Electrophoreses and Chromate Electrolyte, available from Waters Corp., 34 Maple St., Milford, MA 01757, Telephone: 508/482-2131, Fax: 508/482-3625.

⁸ Standard Methods Online are available at http://www.standardmethods.org . The year in which each method was approved by the Standard Methods Committee is designated by the last two digits in the method number. The methods listed are the only online versions that may be used.

(c)Sample Collection Methods for IOCs: Sample collection for antimony, arsenic, asbestos, barium, beryllium, cadmium, chromium, cyanide, fluoride, mercury, nickel, nitrate, nitrite, perchlorate, selenium and thallium under 310 CMR 22.06 shall be conducted using the sample preservation, container, and maximum holding time procedures specified in the table below:

Contaminant	Preservative¹	Container²	Time³
Antimony	Con HNO₃ to pH<2	P or G	six months
Arsenic	Con HNO₃ to pH<2	P or G	six months
Asbestos	Cool, 4°C	P or G	48 hours
Barium	Con HNO₃ to pH<2	P or G	six months
Beryllium	Con HNO₃ to pH<2	P or G	six months
Cadmium	Con HNO₃ to pH<2	P or G	six months
Chromium	Con HNO₃ to pH<2	P or G	six months
Cyanide	Cool,4°C, NAOH to pH>12⁴	P or G	14 days
Fluoride	None	P or G	one month
Mercury	Con HNO₃ to pH<2	P or G	28 days
Nickel	Conc HNO₃	P or G	six months
Nitrate
Chlorinated	Cool, 4°C	P or G	14 days
Chlorinated	Con H₂SO₄ to pH<2	P or G	28 days
Non-chlorinated	Cool 4°C	P or G	48 hours
Non-chlorinated	Con H₂SO₄ to pH<2	P or G	28 days
Nitrite	Cool, 4°C	P or G	48 hours
Perchlorate	None	P or G	28 days
Selenium	Con HNO₃ to pH<2	P or G	six months
Thallium	Con HNO₃ to pH<2	P or G	six months

¹ For cyanide determinations samples must be adjusted with sodium hydroxide to pH 12 at the time of collection. When chilling is indicated the sample must be shipped and stored at 4° C or less. Acidification of nitrate or metals samples may be with a concentrated acid or a dilute (50% by volume) solution of the applicable concentrated acid. Acidification of samples for metals analyses is encouraged and allowed at the laboratory rather than at the time of sampling provided the shipping time and other instruction in Section 8.3 of EPA methods 200.78 or 200.8 or 200.9 are followed.

² P = plastic, hard or soft; G = glass, hard or soft.

³ In all cases, samples should be analyzed as soon after collection as possible. Follow additional (if any) information on preservation, containers, or holding times that is specified in the method.

⁴ See method(s) for the information for preservation.

(17)BATs for IOCs: The following are the best technology, Treatment Technique, or other means available for achieving compliance with the Maximum Contaminant Level for inorganic contaminants identified in 310 CMR 22.06(2) except fluoride:

BAT FOR INORGANIC CONTAMINANTS LISTED IN 310 CMR 22.06(2)

CHEMICAL NAME	BAT(s)
Antimony	2,7
Arsenic	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
Perchlorate	5
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

¹ BAT only if influent Hg concentrations <10 µg/l.

² BAT for Chromium III only

³ BAT for Selenium IV only

⁴ BAT for Arsenic V. Pre-oxidation may be required to convert Arsenic III to Arsenic V.

⁵ To obtain high removals; iron to arsenic ratio must be at least 20.1.

(18) The Administrator, pursuant to the Safe Drinking Water Act, Title 14, § 1412, 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.

¹ Section 1412(b)(4)(E)(ii) of SDWA specifies that SSCTs must be affordable and technically feasible for small systems.

² SSCTs for Arsenic V. Pre-oxidation may be required to convert Arsenic III to Arsenic V.

³ The SDWA (ibid.) specifies three categories of small systems:

(i) those serving 25 or more, but fewer than 501,

(ii) those serving more than 500, but fewer than 3,301, and

(iii) those serving more than 3,300, but fewer than 10,001.

⁴ When POU or POE devices are used for compliance, programs to ensure proper long-term operation, maintenance, and monitoring must be provided by the water system to ensure adequate performance.

⁵ Unlikely to be installed solely for arsenic removal. May require pH adjustment to optimal range if high removals are needed.

⁶ Technologies reject a large volume of water-may not be appropriate for areas where water quantity may be an issue.

⁷ To obtain high removals, iron to arsenic ratio must be at least 20:1.

310 CMR, § 22.06

Amended by Mass Register Issue 1309, eff. 3/25/2016.