310 CMR, § 22.05

Current through Register 1536, December 6, 2024

Section 22.05 - Maximum Microbiological Contaminant Levels, Monitoring Requirements and Analytical Methods

(1)Routine Coliform Monitoring.

(a)General Requirements. Each Supplier of Water shall collect total coliform samples at sites which are representative of water throughout the Distribution System, at the entry point to the Distribution System, and at storage facilities. All such samples shall be collected at the frequency applicable to total coliform sampling set forth in the coliform sampling plan for that Supplier of Water's Public Water System. Samples required to be collected at the entry point to the Distribution System, in accordance with an approved coliform sampling plan required by 310 CMR 22.05(1)(a)3., shall be collected in addition to the minimum number of samples required pursuant to 310 CMR 22.05(1)(b), as set forth in 310 CMR 22.05: Table 1. Samples required to be collected at storage facilities, in accordance with an approved coliform sampling plan required by 310 CMR 22.05(1)(a)3., shall be collected in addition to the minimum number of samples required pursuant to 310 CMR 22.05(1)(b), as set forth in 310 CMR 22.05: Table 1, unless otherwise provided in the coliform sampling plan. The Department may require additional routine monitoring samples to ensure adequate Distribution System representation.

1. Each Supplier of Water is required to maintain a Raw Water source sample tap at a location prior to any alteration or treatment of the source water unless otherwise specified by the Department in an approved coliform sampling plan.

a. A Supplier of Water shall collect a Raw Water source sample if the water at the entry point to the Distribution System is not representative of the source, or as otherwise specified in an approved coliform sampling plan required by 310 CMR 22.05(1)(a)3.

b. If a Supplier of Water is required to collect a Raw Water sample under 310 CMR 22.05(1)(a)1.a., then it shall collect the sample monthly on the same day as any one of its required Distribution Samples.

c. A total coliform-positive Raw Water sample shall not trigger the requirements of 310 CMR 22.05(2).

d. In the event of a total coliform-positive Raw Water sample, the Supplier of Water shall comply with the applicable provisions of 310 CMR 22.26(3)(b) and other provisions of 310 CMR 22.26.

2. Community Water Systems and Non-community Non-transient Water Systems are required to install a chemical injection port for Emergency Disinfection. The injection port shall be located prior to the first customer and at a location which maximizes Disinfection contact time.

3.Coliform Sampling Plan. A Supplier of Water shall develop and implement a written coliform sampling plan that identifies sampling sites and a sample collection schedule that are representative of water throughout the Distribution System. These plans, including any revisions to these plans, are subject to Department review, revision and approval. The Supplier of Water shall ensure that an approved sampling plan continues to be representative of water throughout the Distribution System, including seeking Department approval for a sampling plan revision as necessary. Monitoring required by 310 CMR 22.05(1) and (2) may take place at a customer's premises, a Department approved dedicated sampling station, or other designated compliance sampling location. Routine and repeat sample sites and any Sampling Points necessary to meet the requirements of 310 CMR 22.05(1) and (2), and 22.26 must be reflected in the sampling plan.

a. A Supplier of Water shall collect samples at regular time intervals throughout the month, except that a Supplier of Water, whose Public Water System uses only groundwater and serves 4,900 persons or fewer, may collect all required samples on a single day if they are taken from different sampling locations.

b. A Supplier of Water shall take at least the minimum number of required samples even if the Public Water System has had an E. coli MCL violation or has exceeded the coliform Treatment Technique triggers in 310 CMR 22.05(4)(a).

c. A Supplier of Water, subject to Department approval, may conduct more compliance monitoring than is required by 310 CMR 22.05(1) to investigate potential problems in the Distribution System and use monitoring as a tool to assist in uncovering problems. If a Supplier of Water takes more than the minimum number of required routine samples at the locations specified in the existing coliform sampling plan, then the Supplier of Water shall include those sampling results in calculating whether the coliform Treatment Technique trigger in 310 CMR 22.05(4)(a)1.a. or b. has been exceeded. If a Supplier of Water takes samples at locations not previously specified in the existing coliform sampling plan, and the Department determines that these locations are representative of water throughout the Distribution System, the Supplier of Water shall include those sampling results in calculating whether the coliform Treatment Technique trigger in 310 CMR 22.05(4)(a)1.a. or b. has been exceeded.

d. A Supplier of Water shall identify repeat monitoring locations in the coliform sampling plan. Unless a Supplier of Water has obtained the Department's approval pursuant to 310 CMR 22.05(1)(a)3.d.i. or ii., that Supplier of Water 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 service connection away from the end of the Distribution System, the Supplier of Water must still take all required repeat samples. The Supplier of Water, subject to Department approval, may propose an alternative sampling location in lieu of the requirement to collect at least one repeat sample upstream or downstream of the original sampling site in accordance with 310 CMR 22.05(1)(a)3.d.i. or ii. Except as provided for in 310 CMR 22.05(1)(a)3.d.ii., a Supplier of Water required to conduct triggered source water monitoring under 310 CMR 22.26 shall take groundwater source sample(s) in addition to repeat samples required under 310 CMR 22.05(1)(a)3.d.

i. A Supplier of Water may propose repeat monitoring locations to the Department that the Supplier of Water believes to be representative of a pathway for contamination of the Distribution System. A Supplier of Water may elect to specify either alternative fixed locations or criteria for selecting repeat sampling sites on a situational basis in a standard operating procedure (SOP) in its coliform sampling plan. The Supplier of Water must design its SOP to focus the repeat samples at locations that best verify and determine the extent of potential contamination of the Distribution System area based on specific situations. The Department may modify the SOP or require alternative monitoring locations as needed in order to meet the requirements of 310 CMR 22.05(1)(a)3.

ii. Groundwater Public Water Systems serving 1,000 or fewer people may propose repeat sampling locations to the Department that differentiate potential source water and Distribution System contamination (e.g., by sampling at entry points to the Distribution System). A groundwater Public Water System with a single well required to conduct triggered source water monitoring may, with written Department approval, take one of its repeat samples at the monitoring location required for triggered source water monitoring under 310 CMR 22.26(3)(a) if the Supplier of Water demonstrates to the Department's satisfaction that the coliform sampling plan remains representative of water quality in the Distribution System. If approved by the Department, the Supplier of Water may use that sample result to meet the monitoring requirements in both 310 CMR 22.05(1)(a)3. and 22.26(3)(a).

A. If a repeat sample taken at the monitoring location required for triggered source water monitoring is E. coli-positive, the Supplier of Water has violated the E. coli MCL and must also comply with 310 CMR 22.26(3)(a)4. If a Supplier of Water takes more than one repeat sample at the monitoring location required for triggered source water monitoring under 310 CMR 22.26, the Supplier of Water may reduce the number of additional source water samples required under 310 CMR 22.26(3)(a) by the number of repeat samples taken at that location that were not E. coli-positive.

B. If a Supplier of Water takes more than one repeat sample at the monitoring location required for triggered source water monitoring under 310 CMR 22.26(3)(a), and more than one repeat sample is E. coli-positive, the system has violated the E. coli MCL and must also comply with 310 CMR 22.26(4)(a)1.

C. If all repeat samples taken at the monitoring location required for triggered source water monitoring are E. coli-negative and a repeat sample taken at a monitoring location other than the one required for triggered source water monitoring is E. coli-positive, the system has violated the E. coli MCL, but is not required to comply with 310 CMR 22.26(3)(a)4.

e. The Department may review, revise, and approve, as appropriate, repeat sampling proposed by a Supplier of Water under 310 CMR 22.05(1)(a)3.d.i. or ii. The Supplier of Water shall demonstrate that the coliform sampling plan remains representative of the water quality in the Distribution System. The Department may determine that monitoring at the entry point to the Distribution System (especially for undisinfected groundwater Public Water Systems) is effective to differentiate between potential source water and Distribution System problems.

f. 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 whether the coliform Treatment Technique trigger has been exceeded. Repeat samples taken pursuant to 310 CMR 22.05(2) are not considered special purpose samples, and must be used to determine whether the coliform Treatment Technique trigger has been exceeded.

(b)Coliform Monitoring Frequency. The minimum number of total coliform samples for Public Water Systems is based on the population served by the Public Water System according to 310 CMR 22.05: Table 1.

310 CMR 22.05: Table 1

TOTAL COLIFORM MONITORING FREQUENCY

FOR PUBLIC WATER SYSTEMS

Population Served	Minimum Number of Samples Per Month
Up 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

¹ Includes Public Water Systems which have at least 15 service connections, but serve fewer than 25 people.

(c) Routine monitoring requirements for Community Water Systems serving 1,000 or fewer people using only groundwater.

1. Following any total coliform-positive sample taken under 310 CMR 22.05(1), Public Water Systems must comply with the repeat monitoring requirements and E. coli analytical requirements in 310 CMR 22.05(2).

2. Once all monitoring required by 310 CMR 22.05(1)(c) and (2) for a calendar month has been completed, Suppliers of Water must determine whether any coliform Treatment Technique triggers specified in 310 CMR 22.05(4)(a) have been exceeded. If any trigger has been exceeded, Suppliers of Water must complete assessments as required by 310 CMR 22.05(4)(b).

3.Monitoring Frequency for Total Coliforms. All Suppliers of Water described in 310 CMR 22.05(1)(c). shall monitor for total coliforms monthly. No such Supplier of Water shall be eligible for quarterly monitoring.

4. Each Public Water System shall be subject to a special monitoring evaluation by the Department during each Sanitary Survey to review the status of the Public Water System, including the Distribution System, and to determine whether the Public Water System is on an appropriate monitoring schedule. After the Department has performed the special monitoring evaluation during each Sanitary Survey, the Supplier of Water may be required by the Department to modify the Public Water System's monitoring schedule, as necessary, or it may allow the Public Water System to stay on its existing monitoring schedule, consistent with 310 CMR 22.05(1)(c).

(d) Routine monitoring requirements for Non-community Water Systems serving 1,000 or fewer people using only groundwater.

1.General.

a. 310 CMR 22.05(1)(d) shall apply to Non-community Water Systems using only groundwater (except Groundwater Under the Direct Influence of Surface Water, as defined in 310 CMR 22.02(1)) and serving 1,000 people or fewer.

b. Any Supplier of Water who takes a sample pursuant to 310 CMR 22.05(1)(d) that is total coliform-positive shall comply with the repeat monitoring requirements and E. coli analytical requirements set forth in 310 CMR 22.05(2).

c. Once a Supplier of Water completes all monitoring required by 310 CMR 22.05(1)(d) and (2) for a calendar month, the Supplier of Water shall determine whether any coliform Treatment Technique triggers specified in 310 CMR 22.05(4) have been exceeded. If any such trigger has been exceeded, the Supplier of Water shall complete assessments as required by 310 CMR 22.05(4).

d. A Supplier of Water for the purpose of determining eligibility for remaining on or qualifying for quarterly monitoring under 310 CMR 22.05(1)(d)4.a. and 5.d., respectively, for Transient Non-community Water Systems, may request, subject to approval from the Department, not to count monitoring violations under 310 CMR 22.05(11)(c)1. if the missed sample is collected no later than the end of the monitoring period following the monitoring period in which the sample was missed. The Supplier of Water shall collect the make-up sample in a different week than the routine sample for that monitoring period and as soon as possible during the monitoring period. Provided, however, that no such Department approval not to count a monitoring violation shall affect a determination made under 310 CMR 22.05(11)(c)1. nor an obligation to report under 310 CMR 22.05(12)(a)4.

2.Monitoring Frequency for Total Coliforms. All Suppliers of Water described in 310 CMR 22.05(1)(d)1.a. shall monitor for total coliforms each calendar month that its Public Water System provides water to the public or as provided under 310 CMR 22.05(1)(d)3. through 5., or 7. Provided, however, a Seasonal System shall meet the monitoring requirements set forth in 310 CMR 22.05(1)(d)6.

3.Special Monitoring Evaluation for Public Water Systems During Sanitary Survey. Each Public Water System shall be subject to a special monitoring evaluation by the Department during each Sanitary Survey to review the status of its compliance with 310 CMR 22.05(1)(a) and (b) and to determine whether it is on an appropriate monitoring schedule. After the Department has performed the special monitoring evaluation during each Sanitary Survey, the Supplier of Water may be required by the Department to modify its monitoring schedule, as necessary, or may be allowed to stay on its existing monitoring schedule, consistent with the requirements of 310 CMR 22.05. Provided, however, that no Supplier of Water shall be allowed to begin less frequent monitoring under the special monitoring evaluation unless its Public Water System has already met the applicable criteria for less frequent monitoring in 310 CMR 22.05(1)(d)4. For Seasonal Systems on quarterly monitoring, the special monitoring evaluation shall include review of the approved coliform sampling plan, which must designate the time period(s) for monitoring based on site-specific considerations (e.g., during periods of highest demand or highest vulnerability to contamination). Seasonal Systems shall collect compliance samples during these time periods.

4.Criteria for Quarterly Monitoring. Notwithstanding 310 CMR 22.05(1)(d)2., any Supplier of Water approved in writing by the Department for quarterly monitoring prior to April 1, 2016 may remain on quarterly monitoring unless the Department determines otherwise pursuant to 310 CMR 22.05(1)(d)3. and except as provided in 310 CMR 22.05(1)(d)5. A Supplier of Water may submit a written request to reduce the monitoring frequency for its Public Water System from monthly monitoring to quarterly monitoring, subject to the following requirements. The Supplier of Water must demonstrate, subject to the Department's written approval, that its Public Water System meets the criteria set forth in 310 CMR 22.05(1)(d)4.a. through f.

a. The Public Water System must have a Clean Compliance History for the preceding 12 months;

b. The Public Water System must be found to be free of Sanitary Defects based upon one or more of the following, which must have occurred during the preceding 12 months:

i. a Sanitary Survey;

ii. a site visit completed by the Department;

iii. a voluntary Level 2 Assessment by a Person approved by the Department.

c. The Public Water System is in compliance with 310 CMR 22.21(1)(b)3. through 5., (3)(b) and (4);

d. The Public Water System must be in compliance with the certified operator provisions under 310 CMR 22.11B;

e. The Public Water System is not required to disinfect for microbiological contaminants by the Department pursuant to 310 CMR 22.05; and

f. The Public Water System must be constructed in compliance with 310 CMR 22.04.

5. Increased monitoring requirements for Public Water Systems on quarterly monitoring. A Supplier of Water who operates a Public Water System on quarterly monitoring that experiences any of the events identified in 310 CMR 22.05(1)(d)5.a., through d. shall begin monthly monitoring the month following the event. The Supplier of Water shall continue monthly monitoring until approved to return to quarterly monitoring in accordance with 310 CMR 22.05(1)(d)4. A Public Water System on monthly monitoring for reasons other than those identified in 310 CMR 22.05(1)(d)5.a. through d. is not considered to be on increased monitoring for the purposes of 310 CMR 22.05(1)(d)4.

a. The Public Water System triggers a Level 2 assessment or two Level 1 assessments under 310 CMR 22.05(4) in a rolling 12-month period.

b. The Public Water System has an E. coli MCL violation.

c. The Public Water System has a coliform treatment technique violation.

d. The Public Water System has two monitoring violations under 310 CMR 22.05(11)(c) or one monitoring violation under 310 CMR 22.05(11)(c) and one Level 1 assessment under 310 CMR 22.05(4) in a rolling 12-month period.

6.Seasonal Systems.

a. A Supplier of Water who owns or operates a Seasonal System shall demonstrate completion of a Department approved start-up procedure prior to serving water to the public each season, including start-up sampling, in accordance with the following requirements. A written start-up procedure signed by the Supplier of Water shall be submitted no less than seven days prior to serving water to the public each season, and shall be deemed approved unless the Department otherwise notifies the Supplier of Water prior to the date the Supplier of Water will begin serving water to the public, provided that the written start-up procedure includes all of the following elements:

i. notification to the Department and the Primary Operator of the date the Supplier of Water will begin serving water to the public;

ii. inspection of all Seasonal System components including source(s), treatment components, distribution lines and storage tanks;

iii. activation of source(s);

iv. flushing of the entire Distribution System;

v. collection of coliform samples in accordance with the Department-approved coliform sampling plan, including any additional samples representing the re-activated portions of the system;

vi. if the Seasonal System uses chlorination, a requirement that all chlorination equipment be installed and operational and chlorinated water be left in the Distribution System for at least 24 hours and then flushed prior to any coliform sample collection;

vii. a requirement that the Seasonal System disinfect and flush atmospheric storage tank(s) if applicable; and

viii. a requirement to re-install water meters, and re-install and test backflow preventers throughout the Distribution System, if applicable.

Completion of a start-up procedure shall be demonstrated by submitting a description of all start-up activities completed on a Department-approved form, signed by the Supplier of Water, to the Department no less than seven days prior to serving water to the public each season, which shall constitute the Supplier of Water's certification of the completion of the start-up procedure.

b.Monitoring Frequency for Total Coliforms. All Suppliers of Water who operate a Seasonal System described in 310 CMR 22.05(1)(d)1.a. shall monitor for total coliforms each calendar month that it is in operation unless it meets the criteria in 310 CMR 22.05(1)(d)6.b.i. through iii. to be eligible for monitoring less frequently than monthly, except as provided in 310 CMR 22.05(1)(d)3.

i. Seasonal Systems monitoring less frequently than monthly shall have an approved coliform sampling plan that designates the time period for monitoring based on site-specific considerations (e.g., during periods of highest demand or highest vulnerability to contamination). Seasonal Systems shall collect compliance samples during this time period.

ii. To be eligible for quarterly monitoring, the Seasonal System shall meet the criteria in 310 CMR 22.05(1)(d)4.

c. The Supplier of Water may request, subject to approval from the Department, an exemption from some or all of the requirements for Seasonal Systems if the entire Distribution System remains pressurized during the entire period that the Seasonal System is not operating, except that a Seasonal System that monitors less frequently than monthly shall still monitor during the vulnerable period designated by the Department pursuant to the site-specific considerations identified in 310 CMR 22.05(1)(d)6.b.i.

7.Additional Routine Monitoring the Month Following a Total Coliform-positive Sample. A Public Water System collecting samples on a quarterly frequency shall conduct additional routine monitoring the month following one or more total coliform-positive samples (with or without a Level 1 treatment technique trigger). A Public Water System shall collect at least three routine samples during the next month, except that the Supplier of Water may request, subject to approval from the Department a waiver of this requirement if the conditions of 310 CMR 22.05(1)(d)7.a., b., or c. are met. A Public Water System shall either collect samples at regular time intervals throughout the month or shall collect all required routine samples on a single day if samples are taken from different sites. A Public Water System shall use the results of additional routine samples in coliform Treatment Technique trigger calculations under 310 CMR 22.05(4)(a).

a. A Supplier of Water may request, subject to approval from the Department, a waiver of the requirement to collect three routine samples the next month in which the Public Water System provides water to the public if the Department, or an agent approved by the Department, performs a site visit before the end of the next month in which the Public Water System provides water to the public. Although a Sanitary Survey need not be performed, the site visit must be sufficiently detailed to allow the Department to determine whether additional routine monitoring and/or any corrective action is needed. An employee of the Public Water System cannot perform this site visit, even if the employee is an agent approved by the Department to perform Sanitary Surveys.

b. A Supplier of Water may request, subject to approval from the Department, a waiver of the requirement to collect three routine samples the next month in which its Public Water System provides water to the public, if, based upon appropriate submittals:

i. the Department has determined why the sample was total coliform-positive; and

ii. the Department has established that the Public Water System has corrected the problem or will correct the problem before the end of the next month in which the Public Water System serves water to the public.

The waiver shall be effective once the Supplier of Water has received written documentation from the Department of its decision describing the specific cause of the total coliform-positive sample and what action the Public Water System has taken and/or will take to correct this problem, a copy of which shall be made available to EPA and the public.

c. A Supplier of Water shall not receive a waiver of the requirement to collect three additional routine samples the next month in which the system provides water to the public solely on the grounds that all repeat samples are total coliform-negative. A Suppler of Water may request, subject to approval from the Department, a waiver of the requirement for additional routine monitoring the next month if it demonstrates that the contamination problem was corrected before the Supplier of Water is scheduled to take the set of repeat samples required in 310 CMR 22.05(2), and all repeat samples were total coliform-negative.

(e)Routine Monitoring Requirements for Public Water Systems Serving More than 1,000 People.

1. 310 CMR 22.05(1)(e) shall apply to all Public Water Systems serving more than 1,000 people.

2. Following any total coliform-positive sample taken under the provisions of 310 CMR 22.05(1)(e), the Supplier of Water must comply with the repeat monitoring requirements and E. coli analytical requirements in 310 CMR 22.05(2).

3. Once all monitoring required by 310 CMR 22.05(1)(e) and (2) for a calendar month has been completed, the Supplier of Water must determine whether any coliform Treatment Technique triggers specified in 310 CMR 22.05(4) have been exceeded. If any trigger has been exceeded, the Supplier of Water must complete assessments as required by 310 CMR 22.05(4).

4.Monitoring Frequency for Total Coliforms. All Suppliers of Water described in 310 CMR 22.05(1)(e)1. shall monitor for total coliforms monthly, except as provided in 310 CMR 22.05(1)(e)7.

5.Seasonal Systems.

i. notification to the Department and the Primary Operator of the date the Supplier of Water will begin serving water to the public;

ii. inspection of all Seasonal System components including source(s), treatment components, distribution lines and storage tanks;

iii. activation of source(s);

iv. flushing of the entire Distribution System;

v. collection of coliform samples in accordance with the Department-approved coliform sampling plan, including any additional samples representing the re-activated portions of the system;

vii. a requirement that the Seasonal System disinfect and flush atmospheric storage tank(s) if applicable; and

viii. a requirement to re-install water meters, and re-install and test backflow preventers throughout the Distribution System, if applicable.

b. A Supplier of Water who owns or operates a Seasonal System may request, subject to Department approval, an exemption from some or all of the requirements for Seasonal Systems if the entire Distribution System remains pressurized during the entire period that the system is not operating.

6.Unfiltered Surface Water or Groundwater under the Direct Influence of Surface Water. A Public Water System serving more than 1,000 people using Surface Water or Groundwater Under the Direct Influence of Surface Water which does not practice Filtration (in compliance with 310 CMR 22.20A, 22.20D, 22.20F, and 22.20G) must collect at least one total coliform sample Near the First Service Connection each day the Turbidity level of the source water, measured as specified in 310 CMR 22.20A(5)(b)2., exceeds one NTU. When one or more Turbidity measurements in any day exceed one NTU, the Supplier of Water shall collect a coliform sample within 24 hours of the first exceedance, unless the Supplier of Water demonstrates to the Department's satisfaction that, for logistical reasons outside the Supplier of Water's control, it cannot have the sample analyzed within 30 hours of collection and that it has developed an alternative sample collection schedule. Sample results from this coliform monitoring must be included in determining whether the coliform Treatment Technique trigger in 310 CMR 22.05(4)(a) has been exceeded.

7.Reduced Monitoring. No Public Water Systems described in 310 CMR 22.05(1)(e) shall reduce monthly monitoring, except for Non-community Water System using only groundwater (and not Groundwater Under the Direct Influence of Surface Water) serving 1,000 or fewer people in some months and more than 1,000 people in other months. In months when more than 1,000 people are served, the Supplier of Water shall monitor at the frequency specified in 310 CMR 22.05(1)(e). In months when 1,000 or fewer people are served, the Supplier of Water may request, subject to approval from the Department, reducing the monitoring frequency to a frequency allowed under 310 CMR 22.05(1)(d) for a similarly situated Public Water System that always serves 1,000 or fewer people, taking into account the provisions in 310 CMR 22.05(1)(d)4. and 5.

(f) Routine monitoring requirements for Surface Water or Groundwater under the Direct Influence of Surface Water Public Water Systems serving 1,000 or fewer people.

1. 310 CMR 22.05(1)(f) applies to Surface Water or Groundwater under the Direct Influence of Surface Water Public Water Systems serving 1,000 or fewer people.

2. Following any total coliform-positive sample taken under 310 CMR 22.05(1)(f)1., a Supplier of Water shall comply with the repeat monitoring requirements and E. coli analytical requirements in 310 CMR 22.05(2).

3. Once all monitoring required by 310 CMR 22.05(1)(f) and (2) for a calendar month has been completed, a Supplier of Water shall determine whether any coliform Treatment Technique triggers specified in 310 CMR 22.05(4) have been exceeded. If any trigger has been exceeded, a Supplier of Water shall complete assessments as required by 310 CMR 22.05(4).

4.Seasonal Systems.

a. All Seasonal Systems must demonstrate completion of a Department-approved start-up procedure, in accordance with 310 CMR 22.05(1)(d)6.a. and (e)3.a. which includes a requirement for start-up sampling prior to serving water to the public.

b. The Department may exempt any Seasonal System from some or all of the requirements for Seasonal Systems if the entire Distribution System remains pressurized during the entire period that the system is not operating.

5.Monitoring Frequency for Total Coliforms. All Suppliers of Water described in 310 CMR 22.05(1)(f)1. (including consecutive systems) shall monitor for total coliforms monthly. No such Supplier of Water shall be eligible for quarterly monitoring.

6. A Public Water System that uses Surface Water or Groundwater Under the Direct Influence of Surface Water, as defined in 310 CMR 22.02, that does not practice Filtration (in compliance with 310 CMR 22.20A, 22.20D, 22.20F, and 22.20G) must collect at least one total coliform sample Near the First Service Connection each day the Turbidity level of the source water, measured as specified in 310 CMR 22.20A(5)(b)2., exceeds one NTU. This sample must be analyzed for the presence of total coliform. When one or more Turbidity measurements in any day exceeds one NTU, the Supplier of Water must collect this coliform sample within 24 hours of the first exceedance, unless the Department determines that the Supplier of Water, for logistical reasons outside the Supplier of Water 's control, cannot have the sample analyzed within 30 hours of collection and identifies an alternative sample collection schedule. Sample results from this coliform monitoring must be included in determining whether the coliform Treatment Technique trigger in 310 CMR 22.05(4)(a) has been exceeded.

(2)Repeat Monitoring and E. coli Requirements.

(a)Repeat Monitoring. If a sample taken under 310 CMR 22.05(1) is total coliform-positive, the Supplier of Water must collect a set of repeat samples within 24 hours of being notified of the positive result. A Supplier of Water must collect no fewer than three repeat samples for each total coliform-positive sample found. The Supplier of Water may request an extension of the 24-hour limit on a case-by-case basis, subject to Department approval. In order to obtain such approval, the Supplier of Water shall demonstrate a logistical problem in collecting the repeat samples within 24 hours that is beyond its control. In the case of an extension, the Supplier of Water must collect the repeat samples within the amount of time specified by the Department. There shall be no waiver granted from the requirement for a Supplier of Water to collect repeat samples in 310 CMR 22.05(2)(a), (c) and (d).

(b) Unless the provisions of 310 CMR 22.05(1)(a)3.d.i. or ii. are met, the Supplier of Water 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 service connection away from the end of the Distribution System, the Supplier of Water must still take all required repeat samples, using an alternative sampling location approved by the Department in lieu of the requirement to collect at least one repeat sample upstream or downstream of the original sampling site. Except as provided for in 310 CMR 22.05(1)(a)3.d.ii., a Supplier of Water required to conduct triggered source water monitoring under 310 CMR 22.26(3)(a) must take groundwater source sample(s) in addition to repeat samples required under 310 CMR 22.05(2).

(c) A Supplier of Water must collect all repeat samples on the same day, except that a Public Water System with a Single Service Connection, in accordance with a coliform sampling plan approved pursuant to 310 CMR 22.05(1)(a)3., may collect:

1. the required set of repeat samples over a three-day period; or

2. 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 300 ml.

(d) If one or more repeat samples in the current set of repeat samples is total coliform-positive, the Supplier of Water must collect an additional set of repeat samples in the manner specified in 310 CMR 22.05(2)(a), (c) and (d). The additional samples must be collected within 24 hours of being notified of the positive result, unless the Department extends the limit as provided in 310 CMR 22.05(2)(a). A Supplier of Water must continue to collect additional sets of repeat samples until either total coliforms are not detected in one complete set of repeat samples or the Supplier of Water determines that a coliform Treatment Technique trigger in 310 CMR 22.05(4)(a) has been exceeded as a result of a repeat sample being total coliform-positive and notifies the Department in accordance with 310 CMR 22.05(4)(a). If a trigger identified in 310 CMR 22.05(4)(a) is exceeded as a result of a routine samples being total coliform-positive, a Supplier of Water is required to conduct only one round of repeat monitoring for each total coliform-positive routine sample.

(e) After a Supplier of Water 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 Supplier of Water may count the subsequent sample(s) as a repeat sample instead of as a routine sample.

(f) Results of all routine and repeat samples taken under 310 CMR 22.05(1) and 310 CMR 22.05(2) not invalidated by the Department must be used to determine whether a coliform Treatment Technique trigger specified in 310 CMR 22.05(4)(a) has been exceeded.

(g)Escherichia coli (E. coli) Testing.

1. If any routine or repeat sample is total coliform-positive, the Supplier of Water shall analyze that total coliform-positive culture medium to determine if E. coli are present. If E. coli are present the Supplier of Water must notify and consult with the Department as soon as possible but no later than the end of the day when the Supplier of Water learns of an E. coli MCL violation. If the Public Water System receives such notification outside of the Department's regular business hours, then it shall provide notification to the Department by calling the Department's Emergency notification telephone number and using any other electronic reporting tool designated by the Department, or other Department designated numbers.

2. A Supplier of Water may forgo E. coli testing on a total coliform-positive sample provided that the Supplier of Water assumes the total coliform-positive sample is E. coli-positive, in which case the provisions of 310 CMR 22.05(8)(a) shall apply for purposes of determining whether the Public Water System is in compliance with the MCL for E. coli. The Supplier of Water making such assumption shall notify the Department as specified in 310 CMR 22.05(2)(g)1.

(3)Invalidation of Total Coliform Samples. A total coliform-positive sample invalidated under 310 CMR 22.05(3) does not count towards meeting the minimum monitoring requirements of 310 CMR 22.05(1).

(a) A Supplier of Water may request that a total coliform-positive sample be invalidated, subject to Department approval. Any such request shall satisfy the conditions of 310 CMR 22.05(3)(a)1. through 3.

1. The laboratory establishes that improper sample analysis caused the total coliform-positive result.

2. The Supplier of Water demonstrates, on the basis of the results of repeat samples collected as required by 310 CMR 22.05(2)(a) through (d), that the total coliform-positive sample resulted from a domestic or other non-Distribution System plumbing problem. No sample shall be invalidated 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 at a location other than the original tap are total coliform-negative (e.g., no total coliform-positive sample shall be invalidated 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).

3. The Department 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 Supplier of Water must still collect all repeat samples required under 310 CMR 22.05(2)(a) through (d), and use them to determine if a coliform Treatment Technique trigger in 310 CMR 22.05(4) has been exceeded. To invalidate a total coliform-positive sample under 310 CMR 22.05(3)(a)3., the decision and supporting rationale must be documented in writing, and approved and signed by the supervisor of the Department official who recommended the decision. The Department 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 Supplier of Water has taken, or will take to correct this problem. The Department may not invalidate a total coliform-positive sample solely on the grounds that all repeat samples are total coliform-negative.

(b) A laboratory must invalidate a total coliform sample (unless total coliform 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 Supplier of Water 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 Supplier of Water must continue to re-sample within 24 hours and have the samples analyzed until it obtains a valid result. The Department may waive the 24-hour time limit on a case-by-case basis.

(4)Coliform Treatment Technique Triggers and Assessment Requirements for Protection against Potential Fecal Contamination.

(a)Treatment Technique Triggers. A Supplier of Water shall conduct assessments in accordance with 310 CMR 22.05(4)(b) after exceeding any Treatment Technique trigger in 310 CMR 22.05(4)(a)1. or 2.; and shall notify the Department as soon as possible but no later than five calendar days after the collection date of the sample that triggered the assessment.

1.Level 1 Treatment Technique Triggers. Any of the following occurrences is a Level 1 Treatment Technique trigger:

a. for a Supplier of Water taking 40 or more samples per month, the Public Water System exceeds 5.0% total coliform-positive samples for the month;

b. for a Supplier of Water taking fewer than 40 samples per month, the Public Water System has two or more total coliform-positive samples in the same month; or

c. for each Supplier of Water, failure to take every required repeat sample after any single total coliform-positive sample.

2.Level 2 Treatment Technique Triggers. Any of the following occurrences is a Level 2 Treatment Technique trigger:

a. An E. coli MCL violation, as specified in 310 CMR 22.05(11); or

b. A second occurrence of a Level 1 trigger, as defined in 310 CMR 22.05(4)(a)1., within a rolling 12-month period, unless the Department has determined a likely reason that the samples that caused the first Level 1 Treatment Technique trigger were total coliform-positive and has established that the Supplier of Water has corrected the problem.

(b)Requirements for Assessments.

1. Parties responsible for performing assessments.

a.Level 1 Assessments. A Supplier of Water shall ensure that Level 1 Assessments are conducted in order to identify the possible presence of Sanitary Defects and defects in Distribution System coliform monitoring practices. Level 1 Assessments shall be conducted by the Supplier of Water unless notified in writing by the Department, within ten days of the Supplier of Water's Treatment Technique trigger notification to the Department pursuant to 310 CMR 22.05(4)(a) that the Department will conduct the assessment.

b.Level 2 Assessments. A Supplier of Water shall ensure that Level 2 Assessments are conducted, by Department-approved parties, in order to identify the possible presence of Sanitary Defects and defects in Distribution System coliform monitoring practices; unless notified in writing, within ten days of the Supplier of Water's Treatment Technique trigger notification to the Department pursuant to 310 CMR 22.05(4)(a), that the Level 2 Assessment will be conducted by the Department.

c. All assessments shall be submitted in a Department-approved format.

2. When conducting assessments, Suppliers of Water must ensure that the assessor's evaluation includes review and identification of the following elements, at a minimum:

a. inadequacies in sample sites;

b. sampling protocol;

c. sample processing;

d. atypical events that could affect distributed water quality or indicate that distributed water quality was impaired;

e. changes in Distribution System maintenance and operation that could affect distributed water quality (including water storage);

f. source and treatment considerations that bear on distributed water quality, where appropriate (e.g., small groundwater Public Water Systems); and

g. existing water quality monitoring data.

When conducting an assessment under 310 CMR 22.05(4) a Public Water System may integrate any other required assessment (e.g. an assessment under the Groundwater Rule) provided that the integrated assessment shall meet all applicable requirements of all such rules.

3.Level 1 Assessments. A Supplier of Water must conduct a Level 1 Assessment consistent with Department requirements if the Public Water System exceeds one of the Treatment Technique triggers in 310 CMR 22.05(4)(a)1.

a. The Supplier of Water must complete and submit to the Department a Level 1 Assessment as soon as practical after collecting the sample that triggered the assessment in 310 CMR 22.05(4)(a)1., but no later than 30 days after the collection date. In the completed assessment form, (which may include any relevant portions of a corrective action plan submitted under 310 CMR 22.26(4)), the Supplier of Water shall either:

i. describe any Sanitary Defects detected;

ii. describe all corrective actions completed;

iii. propose a timetable for any corrective actions not yet completed;

iv. describe any interim measures it plans to implement for the protection of human health prior to the completion of any corrective actions, including a timetable for doing so; or

v. state that no Sanitary Defects were identified.

b. The Supplier of Water, upon notification from the Department that the Level 1 Assessment is not sufficient (including any proposed timetable for any corrective actions not yet completed) shall consult with the Department regarding the assessment. Following such consultation, the Supplier of Water shall submit a revised assessment on a schedule approved by the Department not to exceed 30 days from the date of the consultation.

c. All Level 1 Assessments, including any revised Level 1 Assessments pursuant to 310 CMR 22.05(4)(b)3.b. shall be subject to the Department's review to determine whether the Supplier of Water has identified a likely cause for the Level 1 trigger and whether the Supplier of Water has corrected the problem, or has included a schedule acceptable to the Department including any Department-specified interim measures, for correcting the problem.

i. The Supplier of Water shall comply with any interim measures, including any specified schedule, specified by the Department for the protection of public health, pending Department approval of the corrective action plan, or the Supplier of Water's completion of the corrective action plan, or both.

ii. No Department-approved corrective action plan may be modified unless such modification is approved by the Department.

4.Level 2 Assessments. A Supplier of Water must ensure that a Level 2 Assessment consistent with Department requirements is conducted if the Public Water System exceeds one of the Treatment Technique triggers in 310 CMR 22.05(4)(a)2. The Supplier of Water shall comply with any expedited actions or additional actions required by the Department in the case of an E. coli MCL violation.

a. Unless the Department notifies the Supplier of Water that the Department intends to conduct the Level 2 Assessment, the Supplier of Water must ensure that a Level 2 Assessment is completed by a party approved by the Department as soon as practical after any trigger in 310 CMR 22.05(4)(a)2. The Supplier of Water must submit a completed Level 2 Assessment form to the Department no later than 30 days after the collection date of the sample that triggered the assessment. The completed assessment form (which may include any relevant portions of a corrective action plan submitted under 310 CMR 22.26(4)) must either:

i. describe any Sanitary Defects detected;

ii. describe all corrective actions completed;

iii. propose a timetable for any corrective actions not yet completed;

iv. describe any interim measures planned for the protection of human health prior to the completion of any corrective actions, including a timetable for performing those interim measures; or

v. state that no Sanitary Defects were identified.

b. The Supplier of Water may conduct Level 2 Assessments if the Public Water System has staff or management with the certification or qualifications specified by the Department unless otherwise directed by the Department.

c. The Supplier of Water, upon notification from the Department that a Level 2 Assessment, the performance of which is ensured by the Supplier of Water, is not sufficient (including any proposed timetable for any corrective actions not yet completed) shall consult with the Department regarding the assessment. Following such consultation, the Supplier of Water shall submit a revised assessment on a schedule approved by the Department not to exceed 30 days from the date of the consultation.

d. Upon the Supplier of Water completing and submitting the assessment form, the Department will determine if the Supplier of Water has identified a likely cause for the Level 2 trigger and if so the Department will determine whether the Supplier of Water has corrected the problem, or has included a schedule acceptable to the Department for correcting the problem.

i. If the Department has specified interim measures for protection of the public health pending Department approval of the corrective action plan and schedule or pending completion of the corrective action plan, or both, the Supplier of Water shall comply with these interim measures, including any specified schedule.

ii. Any subsequent modifications to a Department-approved corrective action plan must also be approved by the Department.

(c)Corrective Action. Supplier of Water shall correct Sanitary Defects found through either Level 1 or Level 2 Assessments conducted under 310 CMR 22.05(4)(b). For corrections not completed by the time of submission of the assessment form, the Supplier of Water shall complete the corrective action(s) in compliance with a timetable approved by the Department in consultation with the Supplier of Water. The Supplier of Water shall notify the Department in writing when each scheduled corrective action is completed.

(d)Consultation. At any time during the assessment or corrective action phase, the Supplier of Water may request a consultation with the Department to determine the appropriate actions to be taken. In addition, the Supplier of Water shall consult with the Department upon written notification from the Department to do so. The Supplier of Water may consult with the Department on all relevant information that may impact its ability to comply with a requirements of 310 CMR 22.05(4), including the method of accomplishment, an appropriate timeframe, and other relevant information.

(5)Maximum Microbiological Contaminant Levels, Monitoring Requirements and Analytical Methods. (Reserved)

(6)Analytical Methodology.

(a) The Standard Sample volume required for analysis, regardless of analytical method used, is 100 ml.

(b) Public Water Systems need only determine the presence or absence of total coliform and E. coli; a determination of density is not required.

(c) The time from sample collection to initiation of test medium incubation shall not exceed 30 hours. Suppliers of Water are encouraged but not required to hold samples below 10°C during transit.

(d) If water having residual chlorine (measured as free, combined, or total chlorine) is to be analyzed, sufficient sodium thiosulfate (Na₂S₂O₃) must be added to the sample bottle before sterilization to neutralize any residual chlorine in the water sample. Dechlorination procedures are addressed in Section 9060A.2 of Standard Methods for the Examination of Water and Wastewater, 20^th edition (1998) and 21^st edition (2005), American Public Health Association, 800 I Street, NW., Washington, DC 20001.

(e) Public Water Systems must conduct total coliform and E. coli analyses in accordance with one of the analytical methods in the following table or one of the alternative methods described in 310 CMR 22.10.

Organism	Methodology Category	Method¹	Citation¹
Total Coliforms	Membrane Filtration Methods .....	Standard Total Coliform Membrane Filter Procedure .......... Membrane Filtration using MI Medium ................ m-ColiBlue24® Test^2,4 ..... Chromocult^2,4 ............	Standard Methods 9222 B, C (20^th ed.; 21^st ed.)^2,4 Standard Methods Online 9222 B-97^2,⁴, 9222 C -97^2,4EPA Method 1604²
Enzyme Substrate Methods .......	Colilert® ............... Colisure® ............... E*Colite®Test² .......... Readycult® Test^2,⁹ modified Colitag® Test² ...........	Standard Methods 9223 B (20^th ed.; 21^st ed.)^2,⁵ Standard Methods 9223 B (20^th ed.; 21^st ed.)^2,^5,⁶ Standard Methods Online 9223 B-97^2,⁵
Escherichia coli	Escherichia coli Partition Method .. Membrane Filtration Methods ..... Enzyme Substrate Methods .......	EC broth with MUG (EC-MUG) .............. NA-MUG medium ........ Membrane Filtration using MI medium m-ColiBlue24® Test^2,⁴ .... Chromocult^2,⁴ ............ Colilert® ............... Colisure® ............... E*Colite® Test²Readycult® Test²modified Colitag® Test²	Standard Methods 9222 G.1 c(2) (20^th ed.; 21^st ed.)^2,⁸ Standard Methods 9222 G.1c(1) (20^th ed.; 21^st ed.)² EPA Method 1604² Standard Methods 9223 B (20^th ed.; 21^st ed.)^2,⁵ Standard Methods Online 9223 B-97^2,^5,⁶ Standard Methods 9223 B (20^th ed.; 21^st ed.)^2,^5,⁶ Standard Methods Online 9223 B-97^2,^5,⁶

¹ The procedures must be done in accordance with the documents listed in 310 CMR 22.05(6)(g). For Standard Methods, either editions, 20^th (1998) or 21^st (2005), may be used. For the Standard Methods Online, the year in which each method was approved by the Standard Methods Committee is designated by the last two digits following the hyphen in the method number. The methods listed are the only online versions that may be used. For vendor methods, the date of the method listed in 310 CMR 22.05(6)(g) is the date/version of the approved method. The methods listed are the only versions that may be used for compliance with this rule. Laboratories should be careful to use only the approved versions of the methods, as product package inserts may not be the same as the approved versions of the methods.

² Incorporated by reference. See 310 CMR 22.05(6)(g).

³ Lactose broth, as commercially available, may be used in lieu of lauryl tryptose broth, if the Public Water System conducts at least 25 parallel tests between lactose broth and lauryl tryptose broth using the water normally tested, and if the findings from this comparison demonstrate that the false-positive rate and false-negative rate for total coliforms, using lactose broth, is less than 10%.

⁴ All Filtration series must begin with Membrane Filtration equipment that has been sterilized by autoclaving. Exposure of Filtration equipment to UV light is not adequate to ensure sterilization. Subsequent to the initial autoclaving, exposure of the Filtration equipment to UV light may be used to sanitize the funnels between filtrations within a Filtration series. Alternatively, Membrane Filtration equipment that is pre-sterilized by the manufacturer (i.e., disposable funnel units) may be used.

⁵ Multiple-tube and multi-well enumerative formats for this method are approved for use in presence-absence determination under 310 CMR 22.00.

⁶ Colisure® results may be read after an incubation time of 24 hours.

⁷ A multiple tube enumerative format, as described in Standard Methods for the Examination of Water and Wastewater 9221, is approved for this method for use in presence-absence determination under this regulation.

⁸ The following changes must be made to the EC broth with MUG (EC-MUG) formulation: Potassium dihydrogen phosphate, KH2PO4, must be 1.5g, and 4-methylumbelliferyl-Beta-D-glucuronide must be 0.05 g.

(f)Laboratory Certification. Public Water Systems must have all compliance samples required under 310 CMR 22.05(1) and 310 CMR 22.05(2) analyzed by a laboratory certified by the Department or EPA to analyze drinking water samples. The laboratory used by the Public Water System must be certified for each method (and associated contaminant(s)) used for compliance monitoring analyses under 310 CMR 22.05(1) and 310 CMR 22.05(2).

(g)Incorporation by Reference. The following standards are incorporated by reference into 310 CMR 22.05.

1. American Public Health Association, 800 I Street, NW., Washington, DC 20001.

a.Standard Methods for the Examination of Water and Wastewater, 20^th edition (1998):

i. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, B, Standard Total Coliform Membrane Filter Procedure.

ii. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, C, Delayed-Incubation Total Coliform Procedure.

iii. Standard Methods 9223, Enzyme Substrate Coliform Test, B, EnzymeSubstrate Test, Colilert and Colisure.

iv. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, G.1.c(2), Escherichia coli Partition Method: EC broth withMUG (EC- MUG).

v. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, G.1.c(1), Escherichia coli Partition Method: NA-MUG medium.

b.Standard Methods for the Examination of Water and Wastewater, 21^st edition (2005):

i. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, B, Standard Total Coliform Membrane Filter Procedure.

ii. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, C, Delayed-Incubation Total Coliform Procedure.

iii. Standard Methods 9223, Enzyme Substrate Coliform Test, B, EnzymeSubstrate Test, Colilert and Colisure.

iv. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, G.1.c(2), Escherichia coli Partition Method: EC broth withMUG (EC- MUG).

v. Standard Methods 9222, Membrane Filter Technique for Members of theColiform Group, G.1.c(1), Escherichia coli Partition Method: NA-MUG medium.

c. Standard Methods Online available at http://www.standardmethods.org.

i. Standard Methods Online 9222, Membrane Filter Technique for Members of the Coliform Group (1997), B-97, Standard Total Coliform Membrane Filter Procedure.

ii. Standard Methods Online 9222, Membrane Filter Technique for Members of the Coliform Group (1997), C-97, Delayed-incubation Total Coliform Procedure.

iii. Standard Methods Online 9223, Enzyme Substrate Coliform Test (1997), B-97, Enzyme Substrate Test, Colilert and Colisure.

2. Charm Sciences, Inc., 659 Andover Street, Lawrence, MA 01843-1032, telephone 1-800-343-2170: E*Colite - Charm E*ColiteTM Presence/Absence Test for Detection and Identification of Coliform Bacteria and Escherichia coli in Drinking Water, January 9, 1998.

3. CPI International, Inc., 5580 Skylane Blvd., Santa Rosa, CA, 95403, telephone 1-800-878-7654: modified Colitag, ATP D05- 0035-Modified ColitagTM Test Method for the Simultaneous Detection of E. coli and other Total Coliforms in Water, August 28, 2009.

4. EMD Millipore (a division of Merck KGaA, Darmstadt Germany), 290 Concord Road, Billerica, MA 01821, telephone 1-800-645-5476:

a. Chromocult - Chromocult Coliform Agar Presence/Absence Membrane Filter Test Method for Detection and Identification of Coliform Bacteria and Escherichia coli for Finished Waters, November 2000, Version 1.0.

b. Readycult - Readycult Coliforms 100 Presence/Absence Test for Detection and Identification of Coliform Bacteria and Escherichia coli in Finished Waters, January 2007, Version 1.1.

5. EPA's Water Resource Center (MC-4100T), 1200 Pennsylvania Avenue NW., Washington, DC 20460, telephone 1-202-566-1729: EPA Method 1604, EPA 821-R-02-024- EPA Method 1604: Total Coliforms and Escherichia coli in Water by Membrane Filtration Using a Simultaneous Detection Technique (MI Medium), September 2002.

6. Hach Company, P.O. Box 389, Loveland, CO 80539, telephone 1-800- 604-3493: m-ColiBlue24 - Membrane Filtration Method m-ColiBlue24 Broth, Revision 2, August 17, 1999.

(7)Maximum Microbiological Contaminant Levels, Monitoring Requirements and Analytical Methods. (Reserved)

(8)Maximum Contaminant Levels (MCLs) for Microbiological Contaminants.

(a) A Public Water System shall be considered to be in compliance with the MCL for E. coli for samples taken under 310 CMR 22.05, unless any of the conditions identified in 310 CMR 22.05(8)(a)1. through 4. occurs. For purposes of the public notification requirements in 310 CMR 22.16, the occurrence of any of the following conditions is a violation that may pose an acute risk to health:

1. the Public Water System has an E. coli-positive repeat sample following an associated total coliform-positive routine sample;

2. the Public Water System has a total coliform-positive repeat sample following an E. coli-positive routine sample;

3. the Supplier of Water fails to take all required repeat samples following an E. coli-positive routine sample; or

4. the Supplier of Water fails to test for E. coli when any repeat sample tests positive for total coliform.

(b) A Supplier of Water shall determine compliance with the MCL for E. coli in 310 CMR 22.05(8)(a) for each month in which it is required to monitor for total coliforms.

(c) As provided in 310 CMR 22.26(3)(a), a Supplier of Water who is in violation of 310 CMR 22.05(8)(a)1. due to an E. coli-positive repeat sample taken at the monitoring location required for triggered source water monitoring under 310 CMR 22.26(3)(a), is also subject to 310 CMR 22.26(3)(a)4.

(9)Best Available Technology, Treatment Techniques.

(a) The following have been determined to provide best available technology, treatment techniques or other means available for achieving compliance with the Maximum Contaminant Level for E. coli in 310 CMR 22.05(8)(a):

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 310 CMR 22.20A, 310 CMR 22.20D, 22.20F, and 22.20G or disinfection of ground water using strong oxidants such as chlorine, chlorine dioxide, or ozone; and

5. For Public Water Systems using groundwater, compliance with the Department's wellhead protection requirements under 310 CMR 22.21(1).

(b) The Department hereby identifies the technology, Treatment Techniques, or other means available identified in 310 CMR 22.05(9)(a)1. through 5. as affordable technology, Treatment Techniques, or other means available to Public Water Systems serving 10,000 or fewer people for achieving compliance with the Maximum Contaminant Level for E. coliin 310 CMR 22.05(8)(a).

(10)Maximum Microbiological Contaminant Levels, Monitoring Requirements and Analytical Methods. (Reserved)

(11)Violations.

(a)E. coli MCL Violation. A Supplier of Water at whose Public Water System any of the conditions identified in 310 CMR 22.05(8)(a)1. through 4. occurs is in violation of the MCL for E. coli.

(b)Treatment Technique Violation. Each of the following occurrences is a Treatment Technique violation:

1. when a Public Water System exceeds a Treatment Technique trigger specified in 310 CMR 22.05(4)(a)1.a. through c. or in 2.a. through b. and the Supplier of Water then fails to conduct the required assessment or corrective actions within the timeframe specified in 310 CMR 22.05(4)(b) and (c). A Supplier of Water that has failed to submit the required assessment form within the timeline specified in 310 CMR 22.05(4)(b)3.a. or 4.a. shall be deemed to have failed to conduct the assessment; or

2. when a Seasonal System fails to complete a Department-approved start-up procedure prior to serving water to the public. A Public Water System that has failed to submit a required start-up certification within the timeframe specified in 310 CMR 22.05(12)(a)5. shall be deemed to have failed to complete the start-up procedure.

(c)Monitoring Violations. Each of the following occurrences is monitoring violation:

1. failure to take every required routine or additional routine sample in a Compliance Period; or

2. failure to analyze for E. coli following a total coliform-positive routine sample is a monitoring violation.

(d)Reporting Violations. Each of the following occurrences is a reporting violation:

1. failure to submit a monitoring report or completed assessment form after a Public Water System properly conducts monitoring or assessment by the deadlines established in 310 CMR 22.15(2)(a) and (b), and 22.05(4)(b)3.a. and 4.a. respectively;

2. failure to notify the Department following an E. coli-positive sample as required by 310 CMR 22.05(12)(a)1.b. and by the deadline established in 310 CMR 22.05(2)(g);

3. failure to submit certification of completion of Department-approved start-up procedure by a Seasonal System by the deadline established in 310 CMR 22.05(1)(d)6.a. or (e)5.a.;

4. failure to notify the Department of a Treatment Technique trigger by the deadline established in 310 CMR 22.05(4)(a); or

5. failure to notify the Department of an E. coli MCL violation in accordance with 310 CMR 22.05(12)(a)1.a.

(12)Reporting and Recordkeeping.

(a)Reporting.

1.E. coli.

a. A Supplier of Water shall notify and consult with the Department as soon as possible but no later than the end of the day when the Supplier of Water learns of an E. coli MCL violation and shall notify the public in accordance with 310 CMR 22.16. If the Supplier of Water receives such notification outside of the Department's regular business hours, then it shall provide notification to the Department by calling the Department's Emergency notification telephone number and using any other electronic reporting tool designated by the Department, or other Department designated numbers.

b. If E. coli are present in a routine sample, the Supplier of Water shall notify and consult with the Department on the same day as the Supplier of Water receives notification from the laboratory. If the Supplier of Water receives such notification outside of the Department's regular business hours, then the Supplier of Water shall on the same day call the Department's Emergency notification telephone number and use any other electronic reporting tool designated by the Department, or other Department designated numbers.

2. A Supplier of Water whose Public Water System has violated the Treatment Technique for coliforms in 310 CMR 22.05(4)(a) shall report the violation to the Department no later than the end of the next business day after it learns of the violation, and notify the public in accordance with 310 CMR 22.16.

3. A Supplier of Water required to conduct an assessment under 310 CMR 22.05(4) shall submit the assessment report as soon as possible but not later than 30 days after the collection date of the sample that triggered the assessment, pursuant to 310 CMR 22.05(4)(b)3.a or 4.a.

The Supplier of Water shall notify the Department in accordance with 310 CMR 22.05(4)(c) when each scheduled corrective action is completed for corrections not completed by the time of submission of the assessment form.

4. A Supplier of Water who has failed to comply with a coliform monitoring requirement shall report the monitoring violation to the Department within ten days after the Supplier of Water discovers the violation and notify the public in accordance with 310 CMR 22.16.

5. At the beginning of each operating period, a Supplier of Water of a Seasonal System shall certify, prior to serving water to the public, that it has complied with the Department-approved start-up procedure in accordance with 310 CMR 22.05(1)(d)6.a. or (e)3.a.

6. A Supplier of Water shall notify the Department as soon as possible but no later than five days after the collection date of the sample that, in accordance with 310 CMR 22.05(4)(a)1. or 2., triggered an assessment.

(b)Recordkeeping.

1. The Supplier of Water shall maintain any assessment form, regardless of who conducts the assessment, and documentation of corrective actions completed as a result of those assessments, or other available summary documentation of the Sanitary Defects and corrective actions taken under 310 CMR 22.05(4), for Department review. This record shall be maintained by the Supplier of Water for a period not less than five years after completion of the assessment or corrective action.

2. The Supplier of Water shall maintain a record of any repeat sample taken that meets Department criteria for an extension of the 24-hour period for collecting repeat samples as provided for under 310 CMR 22.05(2)(a).

310 CMR, § 22.05

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