1. (1) General Requirements.

   1. (a) 310 CMR 22.20A establishes criteria under which Filtration is required as a Treatment Technique for Public Water Systems supplied by Surface Water Sources and groundwater sources under the direct influence of surface water. In addition, 310 CMR 22.20A establishes Treatment Technique requirements in lieu of Maximum Contaminant Levels for the following contaminants:

      1. 1. Giardia lamblia;
      2. 2. Viruses;
      3. 3. Heterotrophic plate count bacteria;
      4. 4. Legionella; and
      5. 5. Turbidity.

   2. (b) Each Supplier of Water with a Surface Water Source, or groundwater source under the direct influence of surface water, must provide treatment of that source water that complies with the Treatment Technique requirements set forth in 310 CMR 22.20A. The Treatment Technique requirements consist of installing and properly operating water treatment processes which reliably achieve:

      1. 1. At least 99.9% (3 log) removal and/or inactivation of Giardia lamblia cysts between a point where the Raw Water is not subject to recontamination by Surface Water runoff and a point downstream before or at the first customer; and
      2. 2. At least 99.99% (4 log) removal and/or inactivation of Viruses between a point where the Raw Water is not subject to recontamination by Surface Water runoff and a point downstream before or at the first customer.

   3. (c) A Supplier of Water using a Surface Water Source or groundwater source under the direct influence of surface water shall be deemed in compliance with the requirements of 310 CMR 22.20A(1)(a) and (b) if:

      1. 1. It meets the requirements for avoiding Filtration in 310 CMR 22.20A(2) and the Disinfection requirements in 310 CMR 22.20A(3)(a); or
      2. 2. It meets the Filtration requirements in 310 CMR 22.20A(4) and the Disinfection requirements in 310 CMR 22.20A(3)(b).
   4. (d) Each Supplier of Water using a Surface Water Source or a groundwater source under the direct influence of surface water must be operated by a Certified Operator in compliance with 310 CMR 22.11B.
   5. (e) In addition to complying with requirements of 310 CMR 22.20A, systems serving at least 10,000 people shall also comply with the requirements of 310 CMR 22.20D.
   6. (f) In addition to complying with the requirements of 310 CMR 22.20A, each Supplier of Water that serves fewer than 10,000 people must also comply with the requirements in 310 CMR 22.20F.

2. (2) Criteria for Avoiding Filtration. A Supplier of Water that uses a Surface Water Source must meet all of the conditions in 310 CMR 22.20A(2)(a) and (b) and is subject to 310 CMR 22.20A(2)(c) beginning June 29, 1991, unless the Department has notified it in writing that Filtration is required. A Supplier of Water that uses a groundwater source under the direct influence of surface water must meet all of the conditions in 310 CMR 22.20A(2)(a) and (b) and is subject to 310 CMR 22.20A(2)(c) beginning 18 months after the Department determines that it is under the direct influence of surface water, or June 29, 1991, whichever is later, unless the Department has notified it in writing that Filtration is required. If the Department determines in writing, before June 29, 1991 that Filtration is required, the Supplier of Water must have installed Filtration and meet the criteria for filtered systems specified in 310 CMR 22.20A(3)(b) and (4) by June 29, 1993. Within 18 months of the failure of a system using a Surface Water Source or a groundwater source under the direct influence of surface water to meet any one of the requirements in 310 CMR 22.20A(2)(a) and (b) or after June 29, 1993, whichever is later, the Supplier of Water must have installed Filtration and meet the criteria for filtered systems specified in 310 CMR 22.20A(3)(b) and (4).

   1. (a) Source Water Quality Conditions.

      1. 1. The fecal coliform concentration must be equal to or less than 20/100 ml, or the total coliform concentration must be equal to or less than 100/100 ml (measured as specified in 310 CMR 22.20A(5)(a)1. and (b)1. in representative samples of the source water immediately prior to the first or only Point of Disinfectant Application in at least 90% of the measurements made for the six previous months that the system served water to the public on an ongoing basis. If a system measures both fecal and total coliform, the fecal coliform criterion, but not the total coliform criterion, in 310 CMR 22.20A(2)(a)1. must be met.

      2. 2. The Turbidity level cannot exceed one NTU (measured as specified in 310 CMR 22.20A(5)(a)1. and (b)2. in representative samples of the source water immediately prior to the first or only Point of Disinfectant Application except that five or fewer Turbidity units may be allowed if the Supplier of Water can demonstrate to the Department that the higher Turbidity does not do any of the following:

         1. a. Interfere with Disinfection.
         2. b. Prevent maintenance of an effective Disinfectant agent throughout the Distribution System; or
         3. c. Interfere with microbiological determinations.

      3. 3. The Turbidity level cannot exceed five NTU (at any time) unless:

         1. a. The Department determines that any such event was caused by circumstances that were unusual and unpredictable; and
         2. b. As a result of any such event, there have not been more than two events in the past 12 months the system served water to the public, or more than five events in the past 120 months the system served water to the public, in which the Turbidity level exceeded five NTU. An "event" is a series of consecutive days during which at least one Turbidity measurement each day exceeds five NTU.

   2. (b) Site Specific Conditions.

      1. 1. A Supplier of Water must meet the requirements of 310 CMR 22.20A(3)(a)1. at least 11 of the 12 previous months that its system served water to the public on an ongoing basis, unless the system fails to meet the requirements during two of the 12 previous months that the system served water to the public, and the Department determines that at least one of the failures was caused by circumstances that were unusual and unpredictable.
      2. 2. A Supplier of Water must meet the requirements of 310 CMR 22.20A(3)(a)2. at all times its system serves water to the public unless otherwise approved by the Department.
      3. 3. A Supplier of Water must meet the requirements of 310 CMR 22.20A(3)(a)3. at all times its system serves water to the public unless the Department determines that any such failure was caused by circumstances that were unusual and unpredictable.
      4. 4. A Supplier of Water must meet the requirements of 310 CMR 22.20A(3)(a)4. on an ongoing basis, unless the Department determines that any such failure was not caused by a deficiency in treatment of the source water.

      5. 5. A Supplier of Water must maintain a Watershed Protection/Control Program that adequately minimizes the potential for contamination by Giardia lamblia cysts, Cryptosporidium oocysts and Viruses. During onsite inspection, the Department will determine whether the Watershed Protection/Control Program is adequate to minimize the potential for contamination by Giardia lamblia cysts, Cryptosporidium oocysts and Viruses in the source water. The adequacy of the Watershed Protection/Control Program to prevent potential contamination of the source water and other contaminants must be based on:

         1. a. The comprehensiveness of the watershed review;
         2. b. The effectiveness of the system's program to monitor and control detrimental activities occurring in the Watershed; and
         3. c. Extent to which the water system has maximized land ownership and/or controlled land use within the Watershed.

         4. d. At a minimum, a Watershed Protection/Control Program shall include the following information:

            1. i. a Watershed description, including maps and accompanying narratives of major physical features, components of the water system, and hydrological characteristics;
            2. ii. the Watershed characteristics and activities which may have an adverse effect on source water quality;
            3. iii. a risk assessment and plan for controlling detrimental activities/events that may have an adverse impact on source water quality;
            4. iv. a plan for monitoring Raw Water quality parameters at locations vulnerable to contamination from detrimental activities;
            5. v. demonstrated control through land ownership and/or land use restrictions on all human activities within the Watershed which may have an adverse impact on the microbiological quality of the source water; and
            6. vi. a management plan for staffing, training and maintaining effective day to day operations (including Emergency response to contamination) and implementing a Department-approved Watershed Control/Protection Program.
            7. vii. a description of activities in the Watershed that affect water quality, projects what adverse activities are expected to occur in the future, describes how the Supplier of Water expects to address them and otherwise complies with 310 CMR 22.20B(9) and 22.21(4), if applicable.
         5. e. The Supplier of Water shall submit an annual report on Department-approved forms to the Department. The annual report shall identify any special concerns about the Watershed and how they are being handled;

      6. 6. The Supplier of Water shall be subject to an annual on site inspection by the Department or a Person designated by the Department to assess the Watershed Protection/Control Program and Disinfection treatment process. A report of the on site inspection which summarizes all findings must be prepared every year. The on site inspection must indicate to the Department's satisfaction that the Watershed Protection/ Control Program and Disinfection treatment process are adequately designed and maintained. The on site inspection must include:

         1. a. A review of the effectiveness of the Watershed Protection/Control Program Plan;
         2. b. A review of the physical condition of the source intake and how well it is protected;
         3. c. A review of the system's equipment maintenance program to ensure there is low probability for failure of the Disinfection process;
         4. d. An inspection of the Disinfection equipment for physical deterioration;
         5. e. A review of operating procedures;
         6. f. A review of data records to ensure that all required tests are being conducted and recorded and Disinfection is effectively practiced; and
         7. g. Identification of any improvements which are needed in the equipment, system maintenance and operation, or data collection.
      7. 7. The Public Water System must not have been identified as a source of a Waterborne Disease Outbreak, or if it has been so identified, the system must have been modified sufficiently to prevent another such occurrence, as determined by the Department.
      8. 8. A Supplier of Water must comply with the Maximum Contaminant Level (MCL) for E. coli in 310 CMR 22.05(8) at least 11 months of the 12 previous months that the system served water to the public, on an ongoing basis, unless the Department determines that failure to meet this requirement was not caused by a deficiency in treatment of the source water.
      9. 9. Each Supplier of Water shall comply with the requirements for Trihalomethanes in 310 CMR 22.07(1) and (2) until December 31, 2001. After January 1, 2002, the Public Water System shall comply with the requirements for Total Trihalomethanes, Haloacetic Acids (Five), bromate, chlorite, chlorine, chloramines and chlorine dioxide as appropriate or applicable depending on Disinfectant used and in accordance with 310 CMR 22.07E.

   3. (c) Treatment Technique Violations.

      1. 1. A Supplier of Water shall be deemed in violation of a Treatment Technique requirement if it:

         1. a. fails to meet any one of the criteria in 310 CMR 22.20A(2)(a) or (b) and/or which the Department has notified in writing that Filtration is required; or
         2. b. fails to install Filtration by the date specified in 310 CMR 22.20A(2).

      2. 2. A Supplier of Water that has not installed Filtration is in violation of a Treatment Technique requirement if:

         1. a. the Turbidity level (measured as specified in 310 CMR 22.20A(5)(a)1. and (b)2.) in a representative sample of the source water immediately prior to the first or only point of Disinfection exceeds one NTU unless five or fewer NTU units have been allowed by the Department; or
         2. b. its system is identified as a source of a Waterborne Disease Outbreak.

3. (3) Disinfection. A Supplier of Water that uses a Surface Water Source and does not provide Filtration treatment must provide the Disinfection treatment specified in 310 CMR 22.20A(3)(a) beginning December 29, 1991, unless the Department notifies it in writing that Filtration is required. A Supplier of Water that uses a groundwater source under the direct influence of surface water and does not provide Filtration treatment must provide Disinfection treatment specified in 310 CMR 22.20A(3)(a) beginning December 29, 1991, or 18 months after the Department determines that the groundwater source is under the influence of surface water, whichever is later, unless the Department has notified it in writing that Filtration is required. If the Department has determined that Filtration is required, the Supplier of Water must comply with any interim Disinfection requirements the Department deems necessary before Filtration is installed. A Supplier of Water that uses a Surface Water Source that provides Filtration treatment must provide the Disinfection treatment specified in 310 CMR 22.20A(3)(b) beginning June 29, 1993, or beginning when Filtration is installed, whichever is later. A Supplier of Water that uses a groundwater source under the direct influence of surface water and provides Filtration treatment must provide Disinfection treatment as specified in 310 CMR 22.20A(3)(b) by June 29, 1993, or beginning when Filtration is installed, whichever is later. Failure to meet any requirement in 310 CMR 22.20A(3) after the applicable date is a Treatment Technique violation.

   1. (a) Disinfection requirements for Public Water Systems that do not provide Filtration. A Supplier of Water that does not provide Filtration treatment must provide Disinfection treatment as follows:

      1. 1. The Disinfection treatment must be sufficient to ensure at least 99.9% (3 log) inactivation of Giardia lamblia cysts and 99.99% (4 log) inactivation of Viruses, every day the system serves water to the public, except any one day each month. Each day a system serves water to the public, the Supplier of Water must calculate the CT value(s) from the system's treatment parameters, using the procedure specified in 310 CMR 22.20A(5)(b)3., and determine whether this value(s) is sufficient to achieve the specified inactivation rates for Giardia lamblia cysts and Viruses. If a system uses a Disinfectant other than chlorine, the Supplier of Water may demonstrate to the Department, through the use of a Department approved protocol for on site Disinfection challenge studies or other information satisfactory to the Department, that CT99.9 values other than those specified in 310 CMR 22.20A(5)(b)3.: Tables 2.1 and Table 3.1 in or other operational parameters are adequate to demonstrate that the system is achieving the minimum inactivation rates required by 310 CMR 22.20A(3)(a).
      2. 2. The Disinfection system must have redundant components, including an auxiliary power supply with automatic start up and alarm to ensure that Disinfectant application is maintained continuously while water is being delivered to the Distribution System unless otherwise approved by the Department.
      3. 3. The Residual Disinfectant Concentration in the water entering the Distribution System, measured as specified in 310 CMR 22.20A(5)(a)2. and (b)5., cannot be less than 0.2 mg/l for more than four hours.
      4. 4. The Residual Disinfectant Concentration in the Distribution System measured as free chlorine, total chlorine, combined chlorine, or chlorine dioxide, as specified in 310 CMR 22.20A(5)(a)2. and (b)6., cannot be undetectable in more than 5% of the samples each month, for any two consecutive months that the system serves water to the public. Water in the Distribution System with a heterotrophic bacteria concentration less than or equal to 500/ml, measured as heterotrophic plate count (HPC) as specified in 310 CMR 22.20A(5)(a)1., is deemed to have a detectable Disinfectant residual for purposes of determining compliance with this requirement. Thus, the value "V" in the following formula cannot exceed 5% in one month, for any two consecutive months.

      Where: a = number of instances where the Residual Disinfectant Concentration is measured; b = number of instances where the Residual Disinfectant Concentration is not measured but heterotrophic bacteria plate count (HPC) is measured; c = number of instances where the Residual Disinfectant Concentration is measured but not detected and no HPC is measured; d = number of instances where the Residual Disinfectant Concentration is measured but not detected and where the HPC is >500/ml; and e = number of instances where the Residual Disinfectant Concentration is not measured and HPC is >500/ml.

   2. (b) Disinfection Requirements for Public Water Systems Which Provide Filtration. A Supplier of Water that provides Filtration treatment must provide Disinfection treatment as follows:

      1. 1. a. The Disinfection treatment must be sufficient to ensure that the total treatment processes of that system achieve at least 99% (2-log) removal of Cryptosporidium, at least 99.9% (3 log) inactivation and/or removal of Giardia lamblia cysts and at least 99.99% (4 log) inactivation and/or removal of Viruses, as determined by the Department.

         1. b. Failure to provide this Disinfection treatment on a daily basis constitutes a treatment technique violation of 310 CMR 22.20A(3)(b)1. The Department must be notified within 24 hours of the failure to provide Disinfection as required.
      2. 2. The Residual Disinfectant Concentration in the water entering the Distribution System, measured as specified in 310 CMR 22.20A(5)(a)2. and (c)2., cannot be less than 0.2 mg/l for more than four hours.
      3. 3. The Residual Disinfectant Concentration in the Distribution System, measured as free chlorine, total chlorine, combined chlorine, or chlorine dioxide, as specified in 310 CMR 22.20A(5)(a)2. and (c)3., cannot be undetectable in more than 5% of the samples each month, for any two consecutive months that the system serves water to the public. Water in the Distribution System with a heterotrophic bacteria concentration less than or equal to 500/ml, measured as heterotrophic plate count (HPC) as specified in 310 CMR 22.20A(5)(a)1., is deemed to have a detectable Disinfectant residual for purposes of determining compliance with this requirement. Thus the value "V" in the following formula cannot exceed 5% in one month, for any two consecutive months.

      Where: a = number of instances where the Residual Disinfectant Concentration is measured; b = number of instances where the Residual Disinfectant Concentration is not measured but heterotrophic bacteria plate count (HPC) is measured; c = number of instances where the Residual Disinfectant Concentration is measured but not detected and no HPC is measured; d = number of instances where no Residual Disinfectant Concentration is measured but not detected and where the HPC is >500/ml; and e = number of instances where the Residual Disinfectant Concentration is not measured and HPC is >500/ml.

4. (4) Filtration. A Supplier of Water that uses a Surface Water Source or a groundwater source under the direct influence of surface water, and does not meet all of the criteria in 310 CMR 22.20A(2)(a) and (b) for avoiding Filtration, must provide treatment consisting of both Disinfection, as specified in 310 CMR 22.20A(3)(b), and Filtration treatment which complies with the requirements of 310 CMR 22.20A(4) by June 29, 1993, or within 18 months of the failure to meet any one of the criteria for avoiding Filtration in 310 CMR 22.20A(2)(a) and (b), whichever is later. Failure to meet any requirement of 310 CMR 22.20A after the date specified in 310 CMR 22.20A(4) is a Treatment Technique violation.

   1. (a) Conventional Filtration Treatment or Direct Filtration.

      1. 1. Beginning January 1, 2002, systems using conventional and Direct Filtration treatment serving at least 10,000 people shall meet the Turbidity requirements in 310 CMR 22.20D(4) and (5).
      2. 2. Beginning January 1, 2005, systems serving less than 10,000 people must meet the Turbidity requirements in 310 CMR 22.20F(6) and (7).

   2. (b) Slow Sand Filtration.

      1. 1. For systems using Slow Sand Filtration, the Turbidity level of representative samples of a system's filtered water must be less than or equal to one NTU in at least 95% of the measurements taken each month, measured as specified in 310 CMR 22.20A(5)(a)1. and (c)1.
      2. 2. The Turbidity level of representative samples of a system's filtered water must at no time exceed five NTU, measured as specified in 310 CMR 22.20A(5)(a)1. and (c)1.

   3. (c) Diatomaceous Earth Filtration.

      1. 1. For systems using Diatomaceous Earth Filtration, the Turbidity level of representative samples of a system's filtered water must be less than or equal to one NTU in at least 95% of the measurements taken each month, measured as specified in 310 CMR 22.20A(5)(a)1. and (c)1.
      2. 2. The Turbidity level of representative samples of a system's filtered water must at no time exceed five NTU, measured as specified in 310 CMR 22.20A(5)(a)1. and (c)1.
   4. (d) Other Filtration Technologies. Each Supplier of Water may use a Filtration technology not listed in 310 CMR 22.20A(4)(a) through (c), if it demonstrates to the Department, using pilot plant studies or other means, that the alternative Filtration technology, in combination with Disinfection treatment that meets the requirements of 310 CMR 22.20A(3)(b), consistently achieves 99.9% removal and/or inactivation of Giardia lamblia cysts and 99.99% removal and/or inactivation of Viruses. For a Supplier of Water that makes this demonstration, the requirements of 310 CMR 22.20A(3)(b) apply. Beginning January 1, 2002, a Supplier of Water serving at least 10,000 people shall meet the requirements for other Filtration technologies as required in 310 CMR 22.20D(4)(b). Beginning January 1, 2005, a Supplier of Water serving fewer than 10,000 people must meet the requirements for other Filtration technologies as required in 310 CMR 22.20F(6)(c).

5. (5) Analytical and Monitoring Requirements.

   1. (a) Analytical Requirements. Only the analytical method(s) specified in 310 CMR 22.20A(5)(a), or otherwise approved by EPA, may be used to demonstrate compliance with the requirements of 310 CMR 22.20A(2), through (4). Measurements for pH, temperature, Turbidity, and Residual Disinfectant Concentrations must be conducted by a certified operator. Measurements for total coliform, fecal coliform, and HPC must be conducted by a laboratory certified by the Department to do such analyses. The following procedures shall be performed in accordance with the publications listed in the 310 CMR 22.20A(6). This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies of the methods published in Standard Methods for the Examination of Water and Wastewater may be obtained from the American Public Health Association, 1015 Fifteenth Street, N.W., Washington, D.C. 20005; copies of the Minimal Medium ONPG MUG Method as set forth in the article National Field Evaluation of a Defined Substrate Method for the Simultaneous Enumeration of Total Coliform and Escherichia coli from Drinking Water: Comparison with the Standard Multiple Tube Fermentation Method (Edberg et al.), Applied and Environmental Microbiology, Volume 54, pp.1594 1601, June 1988 (as amended under Erratum, Applied and Environmental Microbiology, Volume 54, p. 3197, December 1988), may be obtained from the American Water Works Association Research Foundation, 6666 West Quincy Avenue, Denver, Colorado, 80235; and copies of the Indigo Method as set forth in the article Determination of Ozone in Water by the Indigo Method (Bader and Hoigne), may be obtained from Ozone Science & Engineering, Pergamon Press Ltd., Fairview Park, Elmsford, New York 10523. Copies may be inspected at the U.S. Environmental Protection Agency, Room EB15, 401 M Street, S.W., Washington, D.C. 20460 or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700 Washington, D.C.

      1. 1. Public Water Systems must conduct analysis of pH and temperature in accordance with one of the methods listed in 310 CMR 22.06B(10). Public Water Systems must conduct analysis of total coliforms, fecal coliforms, Heterotrophic bacteria, and Turbidity in accordance with one of the following analytical methods and by using analytical test procedures contained in Technical Notes on Drinking Water Methods, EPA-600/R-94-173, October 1994, which is available at NTIS PB95-104766.

   Organism Methodology Citiation1 Total Coliform2 Total Coliform Fermentation Technique3, 4, 5 9221 A, B, C

   Total Coliform Membrane Filter Technique6 9222 A, B, C ONPG-MUG Test7 9223

   Fecal Coliforms2 Fecal Coliform Procedure8 9221 E

   Fecal Coliform Filter Procedure 9222 D

   Heterotrophic bacteria2 Pour Plate Method 9215 B

   SimPlate11 2130 B

   Turbidity13 180.19

   Nephelometric Method Method 210 Nephelometric Method 1013312 Great Lakes Instruments Hach Filter Trak

The procedures shall be done in accordance with the documents listed below. The incorporation by reference of the following documents listed in footnotes 1, 6, 7, 9 and 10 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 800-426-4791. Documents may be inspected at EPA's Drinking Water Docket, 1200 Pennsylvania Ave., NW., Washington, DC 20460 (Telephone: 202-260-3027); or at the Office of the Federal Register, 800 North Capitol Street, NW, Suite 700, Washington, D.C. 20408.

1 Except where noted, all methods refer to Standard Methods for the Examination of Water and

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Wastewater, 18 edition (1992), 19 edition (1995), or 20 edition (1998), American Public Health Association, 1015 Fifteenth Street NW, Washington, D.C. 20005. The cited methods published in any of these three editions may be used. In addition, the following online versions may also be used: 2130 B-01, 9215 B-00, 9221 A, B, C, E-99, 9222 A, B, C, D-97, and 9223 B-97. 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.

2 The time from sample collection to initiation of analysis may not exceed eight hours. Systems must hold samples below 10°C during transit. 3 Lactose broth, as commercially available, may be used in lieu of lauryl tryptose broth, if the system conducts at least 25 parallel tests between this medium and lauryl tryptose broth using the water normally tested, and this comparison demonstrates that the false-positive rate and false-negative rate for total coliform, using lactose broth, is less than 10%. 4 Media should cover inverted tubes at least ½ to b after the sample is added. 5 No requirement exists to run the completed phase on 10% of all total coliform-positive confirmed tubes. 6 MI agar also may be used. Preparation and use of MI agar is set forth in the article, New Medium for the Simultaneous Detection of Total Coliform and Escherichia Coli in Water by Brenner, K.P., et al., 1993, Appl. Environ. Microbiol. 59:3534-3544. Also available from the Office of Water Resource Center (RC-4100), 1200 Pennsylvania Ave., NW, Washington, DC 20460, EPA 600/J-99/225. 7 The ONPG-MUG Test is also known as the Autoanalysis Colilert System. 8 A-1 Broth may be held up to seven days in a tightly closed screw cap tube at 4°C. 9 Methods for the Determination of Inorganic Substances in Environmental Samples, EPA/600/R-93/100, August 1993. Available at NTIS, PB94-121811. 10 th GLI Method 2, Turbidity, November 2, 1992, Great Lakes Instruments, Inc., 8855 North 55 Street, Milwaukee, Wisconsin 53223. 11 A description of the SimPlate method, IDEXX SimPlate TM HPC Test Method for Heterotrophs in Water, November 2000, can be obtained from IDEXX Laboratories, Inc., 1 IDEXX Drive, Westbrook, ME 04092, telephone 800-321-0207. 12 A description of the Hach Filter Trak Method 10133, Determination of Turbidity by Laser Nephelometry, January 2000, Revision 2.0, can be obtained from; Hach Co., P.O. Box 389, Loveland, CO 80539-0389, telephone: 800-227-4224. 13 Styrene divinyl benzene beads (e.g., AMCO-AEPA-1 or equivalent) and stabilized formazin (e.g., Hach StablCal or equivalent) are acceptable substitutes for formazin.

1. 2. Public Water Systems must measure Residual Disinfectant Concentrations with one of the following methods in the following table. Residual Disinfectant Concentrations for free chlorine and combined chlorine also may be measured by using digital meter versions of DPD colorimetric test kits. Suppliers serving less than or equal to 3,300 persons may use non-digital meter DPD colorimetric test kits. Free chlorine and total chlorine may be measured continuously by adapting a specified chlorine residual method for use with a continuous monitoring instrument provided the chemistry, accuracy, and precision remain the same. Instruments used for continuous monitoring must be calibrated with a grab sample measurement at least every five days, or with a protocol approved by the Department. In addition, Public Water Systems may use the ITS free chlorine test strip for the determination of free chlorine. Use of the test strips is described in Method D99-003, Free Chlorine Species (HOCL- and OCL-) by Test Strip, Revision 3.0, November 21, 2003, available from Industrial Test Systems, Inc., 1875 Langston St., Rock Hill, SC 29730.

   1 2

Residual Methodology Methods SM SM Online Other

Free Chlorine Amperometric Titration 4500-Cl D 4500-C1 D-00 D 1253-033

DPD Ferrous Titrimetric 4500-Cl F 4500-C1 F-00 DPD Colorimetric 4500-Cl G 4500-C1 G-00

Total Chlorine Syringaldazine (FACTS) 4500-Cl H 4500 C1 H-00

Amperometric Titration 4500-Cl D 4500 C1 D-00 D 1253-033 Amperometric Titration 4500-Cl E 4500 C1 E-00 (low level measurement) DPD Ferrous Titrimetric 4500-Cl F 4500 C1 F-00

Chlorine Dioxide DPD Colorimetric 4500-Cl G 4500 C1 G-00

Iodometric Electrode 4500-Cl I 4500 C1 I-00 Amperometric Titration 4500-ClO C 2 4500-ClO2 C-00

4500-ClO D 2

DPD Method 4500-ClO E 2

4500 C1O2

Amperometric Titration E-00

Ozone Spectrophotometric 4500-O B 3 327.0, Revision 1.14

4500-O3 B-97

Indigo Method

1

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All the listed Disinfectant residual methods are contained in the 18 , 19 , and 20 editions of Standard Methods for the Examination of Water and Wastewater, 1992, 1995, and 1998; the cited methods published in any of these three editions may be used.

2 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. 3 Annual Book of ASTM Standards, Vol. 11.01, 2004; ASTM International; any year containing the cited version of the method may be used. Copies of this method may be obtained from ASTM International, 100 Barr Harbor Drive, P.O. Box C700 West Conshohocken, PA 19428-2959. 4 EPA Method 327.0, Revision 1.1, Determination of chlorine Dioxide and Chlorite Ion in Drinking Water Using Lissamine Green B and Horseradish Peroxidase with Detection by Visible Spectrophotometry, USEPA, May 2005, EPA 815-R-05-008. Available online at http://www.epa.gov/safewater/methods/sourcalt.html.

1. (b) Monitoring Requirements for Systems that Do Not Provide Filtration. A Supplier of Water that uses a Surface Water Source and does not provide Filtration treatment must begin monitoring, as specified in 310 CMR 22.20A(5)(b) beginning May 1, 1990, unless the Department has notified it in writing that Filtration is required, in which case the Department may specify alternative monitoring requirements, as appropriate, until Filtration is in place. A Supplier of Water that uses a groundwater source under the direct influence of surface water and does not provide Filtration treatment must begin monitoring as specified in 310 CMR 22.20A(5)(b) beginning December 31, 1990 or six months after the Department determines that the groundwater source is under the direct influence of surface water, whichever is later, unless the Department has notified it in writing that Filtration is required, in which case the Department may specify alternative monitoring requirements, as appropriate, until Filtration is in place.

   1. 1. Fecal coliform or total coliform density measurements as required by 310 CMR 22.20A(2)(a)1. must be performed on representative source water samples immediately prior to the first or only Point of Disinfectant Application. The Supplier of Water must sample for fecal or total coliform at the following minimum frequency each week the system serves water to the public:

      System Size (Persons Served) Samples/Week1

      < 500 1 501- 3,300 2

      3,301-10,000 3 10,001-25,000 4 > 25,000 5

      1 Must be taken on separate days.

   In addition, one fecal or total coliform density measurement must be made every day the system serves water to the public and the Turbidity of the source water exceeds one NTU (these samples count towards the weekly coliform sampling requirement) unless the Department determines that the Supplier of Water for logistical reasons outside of the supplier's control, cannot have the sample analyzed within 30 hours of collection. 2. Turbidity measurements as required by 310 CMR 22.20A(2)(a)2. must be performed on representative grab samples of source water immediately prior to the first or only Point of Disinfectant Application every four hours (or more frequently) that the system serves water to the public. A Supplier of Water may substitute continuous Turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the Department. 3. The total inactivation ratio for each day that the system is in operation must be determined based on the CT99.9 values in 310 CMR 22.20A(5)(b)3.: Tables 1.1 through 1.6, Table 2.1 and Table 3.1. The parameters necessary to determine the total inactivation ratio must be monitored as follows:

   1. a. The temperature of the disinfected water must be measured at least once per day at each Residual Disinfectant Concentration Sampling Point.
   2. b. If the system uses chlorine, the pH of the disinfected water must be measured at least once per day at each chlorine Residual Disinfectant Concentration Sampling Point.
   3. c. The Disinfectant Contact Time(s) ("T") must be determined for each day during peak hourly flow.
   4. d. The Residual Disinfectant Concentration(s) ("C") of the water before or at the first customer must be measured each day during peak hourly flow.

   5. e. If a system uses a Disinfectant other than chlorine, the system may demonstrate to the Department, through the use of a Department approved protocol for on site Disinfection challenge studies or other information satisfactory to the Department, that CT99.9 values other than those specified in 310 CMR 22.20A(5)(b)3.: Table 2.1 and Table 3.1 in are adequate to demonstrate that the system is achieving the minimum inactivation rates required by 310 CMR 22.20A(3)(a)1.

      TABLE 1.1 - 310 CMR 22.20A

      CT VALUES (CT ) FOR 99.9% INACTIVATION OF 99.9

GIARDIA LAMBLIA CYSTS BY FREE CHLORINE AT 0.5°C OR LOWER*

Free pH Residual (mg/l) < 6.0 6.5 7.0 7.5 8.0 8.5 < 9.0

< 0.4 137 163 195 237 277 329 390

0.6 141 168 200 239 286 342 407 0.8 145 172 205 246 295 354 422 1.0 148 176 210 253 304 365 437 1.2 152 180 215 259 313 376 451 1.4 155 184 221 266 321 387 464 1.6 157 189 226 273 329 397 477 1.8 162 193 231 279 338 407 489 2.0 165 197 236 286 346 417 500 2.2 169 201 242 297 353 426 511 2.4 172 205 247 298 361 435 522 2.6 175 209 252 304 368 444 533 2.8 178 213 257 310 375 452 543 3.0 181 217 261 316 382 460 552

* These CT values achieve greater than a 99.99% inactivation of Viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT value 99.9 at the lower temperature and at the higher pH.

TABLE 1.2 - 310 CMR 22.20A

CT VALUES (CT ) FOR 99.9% INACTIVATION OF GIARDIA 99.9

LAMBLIA CYSTS BY FREE CHLORINE AT 5.0°C*

pH

Free Residual

(mg/l) < 6.0 6.5 7.0 7.5 8.0 8.5 < 9.0

< 0.4 97 117 139 166 198 236 279

0.6 100 120 143 171 204 244 291 0.8 103 122 146 175 210 252 301 1.0 105 125 149 179 216 260 312 1.2 107 127 152 183 221 267 320 1.4 109 130 155 187 227 274 329 1.6 111 132 158 192 232 281 337 1.8 114 135 162 196 238 287 345 2.0 116 138 165 200 243 294 353 2.2 118 140 169 204 248 300 361 2.4 120 143 172 209 253 306 368 2.6 122 146 175 213 258 312 375 2.8 124 148 178 217 263 318 382 3.0 126 151 182 221 268 324 389

* These CT values achieve greater than a 99.99% inactivation of Viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT value 99.9 at the lower temperature, and at the higher pH. If no interpolation is used, use the CT99.9 value at the lower temperature, and at the higher pH.

TABLE 1.3 - 310 CMR 22.20A

CT VALUES (CT ) FOR 99.9% INACTIVATION OF GIARDIA 99.9

LAMBLIA CYSTS BY FREE CHLORINE AT 10°C*

pH

Free Residual

(mg/l) < 6.0 6.5 7.0 7.5 8.0 8.5 < 9.0

< 0.4 73 88 104 125 149 177 209

0.6 75 90 107 128 153 183 218 0.8 78 92 110 131 158 189 226 1.0 79 94 112 134 162 195 234 1.2 80 95 114 137 166 200 240 1.4 82 98 116 140 170 206 247 1.6 83 99 119 144 174 211 253 1.8 86 101 122 147 179 215 259 2.0 87 104 124 150 182 221 265 2.2 89 105 127 153 186 225 271 2.4 90 107 129 157 190 230 276 2.6 92 110 131 160 194 234 281 2.8 93 111 134 163 197 239 287 3.0 95 113 137 166 201 243 292

* These CT values achieve greater than a 99.99% inactivation of Viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT value 99.9 at the lower temperature, and at the higher pH.

TABLE 1.4 - 310 CMR 22.20A

CT VALUES (CT ) FOR 99.9% INACTIVATION OF GIARDIA 99.9

LAMBLIA CYSTS BY FREE CHLORINE AT 15°C*

pH

Free Residual

(mg/l) < 6.0 6.5 7.0 7.5 8.0 8.5 < 9.0

< 0.4 49 59 70 83 99 118 140

0.6 50 60 72 86 102 122 146 0.8 52 61 73 88 105 126 151 1.0 53 63 75 90 108 130 156 1.2 54 64 76 92 111 134 160 1.4 55 65 78 94 114 137 165 1.6 56 66 79 96 116 141 169 1.8 57 68 81 98 119 144 173 2.0 58 69 83 100 122 147 177 2.2 59 70 85 102 124 150 181 2.4 60 72 86 105 127 153 184 2.6 61 73 88 107 129 156 188 2.8 62 74 89 109 132 159 191 3.0 63 76 91 111 134 162 195

* These CT values achieve greater than a 99.99% inactivation of Viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT value 99.9 at the lower temperature, and at the higher pH.

TABLE 1.5 - 310 CMR 22.20A

CT VALUES (CT ) FOR 99.9% INACTIVATION OF GIARDIA 99.9

LAMBLIA CYSTS BY FREE CHLORINE AT 20°C*

pH

Free Residual

(mg/l) < 6.0 6.5 7.0 7.5 8.0 8.5 < 9.0

< 0.4 36 44 52 62 74 89 105

0.6 38 45 54 64 77 92 109 0.8 39 46 55 66 79 95 113 1.0 39 47 56 67 81 98 117 1.2 40 48 57 69 83 100 120 1.4 41 49 58 70 85 103 123 1.6 42 50 59 72 87 105 126 1.8 43 51 61 74 89 108 129 2.0 44 52 62 75 91 110 132 2.2 44 53 63 77 93 113 135 2.4 45 54 65 78 95 115 138 2.6 46 55 66 80 97 117 141 2.8 47 56 67 81 99 119 143 3.0 47 57 68 83 101 122 146

* These CT values achieve greater than a 99.99% inactivation of Viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT value 99.9 at the lower temperature, and at the higher pH.

TABLE 1.6 - 310 CMR 22.20A

CT VALUES (CT ) FOR 99.9% INACTIVATION OF GIARDIA 99.9

*

LAMBLIA CYSTS BY FREE CHLORINE AT 25°C AND HIGHER

pH

Free Residual

(mg/l) < 6.0 6.5 7.0 7.5 8.0 8.5 < 9.0

< 0.4 24 29 35 42 50 59 70

0.6 25 30 36 43 51 61 73 0.8 26 31 37 44 53 63 75 1.0 26 31 37 45 54 65 78 1.2 27 32 38 46 55 67 80 1.4 27 33 39 47 57 69 82 1.6 28 33 40 48 58 70 84 1.8 29 34 41 49 60 72 86 2.0 29 35 41 50 61 74 88 2.2 30 35 42 51 62 75 90 2.4 30 36 43 52 63 77 92 2.6 31 37 44 53 65 78 94 2.8 31 37 45 54 66 80 96 3.0 32 38 46 55 67 81 97

* These CT values achieve greater than a 99.99% inactivation of Viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT value 99.9 at the lower temperature, and at the higher pH.

TABLE 2.1 - 310 CMR 22.20A

CT VALUES (CT ) FOR 99.9% INACTIVATION OF 99.9

GIARDIA LAMBLIA CYSTS BY CHLORINE DIOXIDE AND OZONE*

Temperature

< 1°C 5°C 10°C 15°C 20°C > 25°C

Chlorine dioxide 63 26 23 19 15 11

Ozone 2.9 1.9 1.4 0.95 0.72 0.48

* These CT values achieve greater than 99.99% inactivation of Viruses. CT values between the indicated temperatures may be determined by linear interpolation. If no interpolation is used, use the CT value 99.9 at the lower temperature for determining CT values between indicated temperatures. 99.9

TABLE 3.1 - 310 CMR 22.20A

CT VALUES (CT ) FOR 99.9% INACTIVATION 99.9 OF GIARDIA LAMBLIA CYSTS BY CHLORAMINE*

Temperature

< 1°C 5°C 10°C 15°C 20°C > 25°C

3,800 2,200 1,850 1,500 1,100 750

* These values are for pH values of 6 through 9. These CT values may be assumed to achieve greater than 99.99% inactivation of Viruses only if chlorine is added and mixed in the water prior to the addition of ammonia. If this condition is not met, the system must demonstrate, based on on-site studies or other information, as approved by the State, that the system is achieving at least 99.99% inactivation of Viruses. CT values between the indicated temperatures may be determined by linear interpolation. If no interpolation is used, use the CT value at the lower temperature for determining CT values between 99.9 99.9 indicated temperatures.

1. 4. The total inactivation ratio must be calculated as follows:

   1. a. If the system uses only one Point of Disinfectant Application, the Supplier of Water may determine the total inactivation ratio based on either of the following two methods:

      1. i. One inactivation ratio (CTcalc/CT ) is determined before or at the first 99.9 customer during peak hourly flow and if the CTcalc/CT > 1.0, the 99.9% 99.9 Giardia lamblia inactivation requirement has been achieved; or

      2. ii. Successive CTcalc/CT values, representing sequential inactivation ratios, 99.9 are determined between the Point of Disinfectant Application and a point before or at the first customer during peak hourly flow. Under this alternative, the following method must be used to calculate the total inactivation ratio:

         1. A. Determine for each sequence.
         2. B. A dd the values together
         3. C. If , then the 99.9% Giardia lamblia inactivation

         requirement has been achieved.

   2. b. If the system uses more than one Point of Disinfectant Application before or at the first customer, the Supplier of Water must determine the CT value of each Disinfection sequence immediately prior to the next Point of Disinfectant Application during peak hourly flow. The CTcalc/CT value of each sequence and 99.9

   must be calculated using the method in 310 CMR 22.20A(5)(b)4.a.ii. to determine if the Supplier of Water is in compliance with 310 CMR 22.20A(3)(a). c. Although not required, the total percent inactivation for a system with one or more points of Residual Disinfectant Concentration following equation:

2. 5. The Residual Disinfectant Concentration of the water entering the Distribution System must be monitored continuously, and the lowest value must be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every four hours may be conducted in lieu of continuous monitoring, but for no more than five working days following the failure of the equipment. Systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies prescribed below:

   System size by population Samples/day*

   < 500 1

   501-1,000 2 1,001-2,500 3 2,501-3,300 4

* The day's samples cannot be taken at the same time. The sampling intervals are subject to Department review and approval.

If at any time the Residual Disinfectant Concentration falls below 0.2 mg/l in a system using grab sampling in lieu of continuous monitoring, the Supplier of Water must take a grab sample every four hours until the Residual Disinfectant Concentration is equal to or greater than 0.2 mg/l. 6. The Residual Disinfectant Concentration must be measured at least at the same points in the Distribution System and at the same time as total coliform are sampled, as specified in 310 CMR 22.05, except that the Department may allow a Supplier of Water which uses both a Surface Water Source or a groundwater source under direct influence of surface water, and a groundwater source, to take Disinfectant residual samples at points other than the total coliform Sampling Points if the Department determines that such points are more representative of treated (disinfected) water quality within the Distribution System. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in 310 CMR 22.20A(5)(a)1., may be measured in lieu of Residual Disinfectant Concentration.

1. (c) Monitoring Requirements for Systems Using Filtration Treatment. A Supplier of Water that uses a Surface Water Source or a groundwater source under the influence of surface water and provides Filtration treatment must monitor in accordance with 310 CMR 22.20A(5)(c) beginning June 29, 1993, or when Filtration is installed, whichever is later.

   1. 1. Turbidity measurements as required by 310 CMR 22.20A(4) must be performed on representative samples of the system's filtered water every four hours (or more frequently) that the system serves water to the public. A Supplier of Water may substitute continuous Turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis using a protocol approved by the Department. For any systems using Slow Sand Filtration, the Department may reduce the sampling frequency to no less than once per day if it determines that less frequent monitoring is sufficient to indicate effective Filtration performance.

   2. 2. The Residual Disinfectant Concentration of the water entering the Distribution System must be monitored continuously, and the lowest value must be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every four hours may be conducted in lieu of continuous monitoring, but for no more than five working days following the failure of the equipment. Systems serving 3,300 or fewer persons may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies each day prescribed below:

      System size by population Samples/day*

      <500 1

      501-1,000 2 1,001-2,500 3 2,501-3,300 4

* The day's samples cannot be taken at the same time. The sampling intervals are subject to Department review and approval.

1. 3. The Residual Disinfectant Concentration must be measured at least at the same points in the Distribution System and at the same time as total coliform are sampled, as specified in 310 CMR 22.05, except that the Department may allow a Supplier of Water which uses both a Surface Water Source or a groundwater source under direct influence of surface water, and a groundwater source to take Disinfectant residual samples at points other than the total coliform Sampling Points if the Department determines that such points are more representative of treated (disinfected) water quality within the Distribution System. Heterotrophic bacteria, measured as heterotrophic plate count
2. (HPC) as specified in 310 CMR 22.20A(5)(a)1., may be measured in lieu of Residual Disinfectant Concentration.

3. (6) Reporting and Recordkeeping Requirements.

   1. (a) A Supplier of Water that uses a Surface Water Source and does not provide Filtration treatment must report monthly to the Department the information specified in 310 CMR 22.20A(6)(a) beginning May 1, 1990, unless the Department has notified the Supplier of Water in writing that Filtration is required in writing, in which case the Department may specify alternative reporting requirements, as appropriate, until Filtration is in place. A Supplier of Water that uses a groundwater source under the direct influence of surface water and does not provide Filtration treatment must report monthly to the Department the information specified in 310 CMR 22.20A(6)(a) beginning December 31, 1990 or six months after the Department determines that the groundwater source is under the direct influence of surface water, whichever is later, unless the Department has notified it in writing that Filtration is required in which case the Department may specify alternative reporting requirements, as appropriate, until Filtration is in place.

      1. 1. Source water quality information must be reported to the Department within ten days after the end of each month the system serves water to the public. Information that must be reported includes:

         1. a. The cumulative number of months for which results are reported.
         2. b. The number of fecal and/or total coliform samples, whichever are analyzed during the month (if a system monitors for both, only fecal coliform must be reported), the dates of sample collection, and the dates when the Turbidity level exceeded one NTU.
         3. c. The number of samples during the month that had equal to or less than 20/100 ml fecal coliform and/or equal to or less than 100/100 ml total coliform, whichever are analyzed.
         4. d. The cumulative number of fecal or total coliform samples, whichever are analyzed, during the previous six months the system served water to the public.
         5. e. The cumulative number of samples that had equal to or less than 20/100 ml fecal coliform or equal to or less than 100/100 ml total coliform, whichever are analyzed, during the previous six months the system served water to the public.
         6. f. The percentage of samples that had equal to or less than 20/100 ml fecal coliform or equal to or less than 100/100 ml total coliform, whichever are analyzed, during the previous six months the system served water to the public.
         7. g. The maximum Turbidity level measured during the month, the date(s) of occurrence for any measurement(s) which exceeded five NTU, and the date(s) the occurrence(s) was reported to the Department.
         8. h. For the first 12 months of recordkeeping, the dates and cumulative number of events during which the Turbidity exceeded five NTU, and after one year of recordkeeping for Turbidity measurements, the dates and cumulative number of events during which the Turbidity exceeded five NTU in the previous 12 months the system served water to the public.
         9. i. For the first 120 months of recordkeeping, the dates and cumulative number of events during which the Turbidity exceeded five NTU, and after ten years of recordkeeping for Turbidity measurements, the dates and cumulative number of events during which the Turbidity exceeded five NTU in the previous 120 months the system served water to the public.

      2. 2. Disinfection information specified in 310 CMR 22.20A(5)(b) must be reported to the Department within ten days after the end of each month the system serves water to the public. Information that must be reported includes:

         1. a. For each day, the lowest measurement of Residual Disinfectant Concentration in mg/l in water entering the Distribution System.
         2. b. The date and duration of each period when the Residual Disinfectant Concentration in water entering the Distribution System fell below 0.2 mg/l and when the Department was notified of the occurrence.
         3. c. The daily Residual Disinfectant Concentration(s) (in mg/l) and Disinfectant Contact Time(s) (in minutes) used for calculating the CT value(s).
         4. d. If chlorine is used, the daily measurement(s) of pH of disinfected water following each point of chlorine Disinfection.
         5. e. The daily measurement(s) of water temperature in C following each point of Disinfection.
         6. f. The daily CTcalc and CTcalc/CT values for each Disinfectant measurement or 99.9 sequence and the sum of all CTcalc/CT values ((CTcalc/CT )) before or at the 99.9 99.9 first customer.
         7. g. The daily determination of whether Disinfection achieves adequate Giardia cyst and Virus inactivation, i.e., whether (CTcalc/CT ) is at least 1.0 or, where 99.9 Disinfectants other than chlorine are used, other indicator conditions that the Department determines are appropriate, are met.

         8. h. The following information on the samples taken in the Distribution System in conjunction with total coliform monitoring pursuant to 310 CMR 22.20A(3):

            1. i. Number of instances where the Residual Disinfectant Concentration is measured;
            2. ii. Number of instances where the Residual Disinfectant Concentration is not measured but heterotrophic bacteria plate count (HPC) is measured; iii Number of instances where the Residual Disinfectant Concentration is measured but not detected and no HPC is measured;
            3. iv. Number of instances where the Residual Disinfectant Concentration is measured but not detected and where HPC is >500/ml;
            4. v. Number of instances where the Residual Disinfectant Concentration is not measured and HPC is >500/ml;
            5. vi. For the current and previous month the system served water to the public, the value of "V" in the following formula:

            Where a = the value in 310 CMR 22.20A(6)(a)2.h.i. b = the value in 310 CMR 22.20A(6)(a)2.h.ii. c = the value in 310 CMR 22.20A(6)(a)2.h.iii. d = the value in 310 CMR 22.20A(6)(a)2.h.iv. e = the value in 310 CMR 22.20A(6)(a)2.h.v.

         9. i. A system need not report the data listed in 310 CMR 22.20A(6)(a)2.a., and c. through f., if all data listed in 310 CMR 22.20A(6)(a)2.a. through f. remains on file at the system, and the Department determines that:

            1. i. The Supplier of Water has submitted to the Department all the information required by 310 CMR 22.20A(6)(a)2.a. through h. for at least 12 months; and

            2. ii. The Department has determined that the system is not required to provide Filtration treatment.

               th

      3. 3. No later than January 10 of each year, each Supplier of Water must provide to the Department a report which summarizes its compliance with all watershed control program requirements specified in 310 CMR 22.20A(2)(b)5.

         th

      4. 4. No later than January 10 of each year each system must provide to the Department a report on the on site inspection conducted during that year pursuant to 310 CMR 22.20A(2)(b)6. unless the on site inspection was conducted by the Department.
      5. 5. Each Supplier of Water, upon discovering that a Waterborne Disease Outbreak potentially attributable to its water system has occurred, must report that occurrence to the Department as soon as possible, but no later than by the end of the next business day.
      6. 6. If at any time the Turbidity exceeds five NTU, the Supplier of Water must consult with the Department as soon as practical, but not later than 24 hours after the exceedance is known, in accordance with the public notification requirements under 310 CMR 22.16(3)(b)3.
      7. 7. If at any time the residual falls below 0.2 mg/l in the water entering the Distribution System, the Supplier of Water must notify the Department as soon as possible, but no later than by the end of the next business day. The Supplier of Water also must notify the Department by the end of the next business day whether or not the residual was restored to at least 0.2 mg/l within four hours.

   2. (b) A Supplier of Water that uses a Surface Water Source or a groundwater source under the direct influence of surface water and provides Filtration treatment must report monthly to the Department the information specified in 310 CMR 22.20A(6)(b) beginning June 29, 1993, or when Filtration is installed, whichever is later.

      1. 1. Turbidity measurements as required by 310 CMR 22.20A(5)(c)1. must be reported within ten days after the end of each month the system serves water to the public. Information that must be reported includes:

         1. a. The total number of filtered water Turbidity measurements taken during the month.
         2. b. The number and percentage of filtered water Turbidity measurements taken during the month which are less than or equal to the Turbidity limits specified in 310 CMR 22.20A(4) for the Filtration technology being used.
         3. c. The date and value of any Turbidity measurements taken during the month which exceed five NTU.

      2. 2. Disinfection information specified in 310 CMR 22.20A(5)(c) must be reported to the Department within ten days after the end of each month the system serves water to the public. Information that must be reported includes:

         1. a. For each day, the lowest measurement of Residual Disinfectant Concentration in mg/l in water entering the Distribution System.
         2. b. The date and duration of each period when the Residual Disinfectant Concentration in water entering the Distribution System fell below 0.2 mg/l and when the Department was notified of the occurrence.

         3. c. The following information on the samples taken in the Distribution System in conjunction with total coliform monitoring pursuant to 310 CMR 22.20A(3):

            1. i. Number of instances where the Residual Disinfectant Concentration is measured;
            2. ii. Number of instances where the Residual Disinfectant Concentration is not measured but heterotrophic bacteria plate count (HPC) is measured;
            3. iii. Number of instances where the Residual Disinfectant Concentration is measured but not detected and no HPC is measured;
            4. iv. Number of instances where Residual Disinfectant Concentration is measured but not detected and where HPC is >500/ml;
            5. v. Number of instances where the Residual Disinfectant Concentration is not measured and HPC is >500/ml;
            6. vi. For the current and previous month the system serves water to the public, the value of "V" in the following formula:

         Where a = the value in 310 CMR 22.20A(6)(b)2.c.i. b = the value in 310 CMR 22.20A(6)(b)2.c.ii. c = the value in 310 CMR 22.20A(6)(b)2.c.iii. d = the value in 310 CMR 22.20A(6)(b)2.c.iv. e = the value in 310 CMR 22.20A(6)(b)2.c.v.

         1. d. A Supplier of Water need not report the data listed in 310 CMR 22.20A(6)(b)2.a. if all data listed in 310 CMR 22.20A(6)(b)2.a. through c. remains on file at the system and the Department determines that the system has submitted all the information required by 310 CMR 22.20A(6)(b)2.a. through c. for at least 12 months.
      3. 3. A Supplier of Water, upon discovering that a Waterborne Disease Outbreak potentially attributable to its water system has occurred, must report that occurrence to the Department as soon as possible, but no later than by the end of the next business day.
      4. 4. If at any time the Turbidity exceeds five NTU, the Supplier of Water must consult with the Department as soon as practical, but not later than 24 hours after the exceedance is known, in accordance with the public notification requirements under 310 CMR 22.16(3)(b)3.
      5. 5. If at any time the residual falls below 0.2 mg/l in the water entering the Distribution System, the Supplier of Water must notify the Department as soon as possible, but no later than by the end of the next business day. The system also must notify the Department by the end of the next business day whether or not the residual was restored to at least 0.2 mg/l within four hours.

4. (7) Review of Filtration Determinations.

   1. (a) The Department's determination whether a Supplier of Water must provide Filtration will be made in writing based on the criteria set forth in 310 CMR 22.20A(2). The Supplier of Water shall publish a copy of the Department's determination in a newspaper of general circulation in the area served by the Supplier of Water within ten days of receipt of the same. The determination will include a statement that the Supplier of Water and Persons served by the system may request a hearing in accordance with 310 CMR 22.20A(7)(b). Within ten days of publication, the Supplier of Water shall submit an affidavit to the Department attesting to the fact that the determination has been published.
   2. (b) The Supplier of Water, and any Person served by the system, may request review of the determination at a public hearing by submitting a written request to the Regional Director at the Department's Regional Office that serves the area where the Public Water System at issue is located within 15 days of the date of publication.
   3. (c) Following receipt of a request for a public hearing, the Department will give notice of the hearing by mail to the Supplier of Water and, if the request was made by a Person other than the Supplier of Water, to the Person who submitted the request. The Supplier of Water shall publish a copy of the notice of hearing in a newspaper of general circulation in the area served by the system within ten days of receipt of the same. Within ten days of publication, the Supplier of Water shall submit an affidavit to the Department attesting to the fact that the notice has been published.
   4. (d) The Department will accept written comments from the public relevant to the determination up to at least 14 days following the hearing. A determination following the hearing that a Supplier of Water must provide Filtration will not be subject to further review; a determination that a Supplier of Water meets all of the criteria for avoiding Filtration will be subject to the Department's on going review. In the event the Department finds that a Supplier of Water no longer meets any one of the criteria for avoiding Filtration, the Department will issue a determination in writing that will be subject to review at a public hearing in accordance with 310 CMR 22.20A(7).