Disinfection Byproduct | MCL (ma/l) |
Total Trihalomethanes (TTHM) | 0.080 |
Haloacetic (Acids Five) (HAA5) | 0.060 |
Bromate | 0.010 |
Chlorite | 1.0 |
Total Trihalomethanes are the sum of the concentrations of bromodichloromethane, dibromochloromethane, tribromomethane (bromoform) and trichloromethane (chloroform) expressed in milligrams per liter (mg/l). Haloacetic acids are the sum of the concentrations of monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid and dibromoacetic acid expressed in milligrams per liter (mg/l).
Compliance Dates. Surface Water and Groundwater under the Direct Influence of Surface Water systems serving 10,000 or more persons must comply with 310 CMR 22.07E(1)(b) beginning January 1, 2002. Surface Water systems and Groundwater under the Direct Influence of Surface Water systems serving fewer than 10,000 persons and systems using only groundwater not under the direct influence of surface water must comply with 310 CMR 22.07E(1)(b) beginning January 1, 2004. All systems must comply with these MCLs until the date specified for Disinfection byproduct compliance in 310 CMR 22.07F(7).
Compliance Dates. The MCLs required under 310 CMR 22.07F for TTHM and HAA5 must be complied with as a Locational Running Annual Average at each monitoring location beginning the date specified for compliance in 310 CMR 22.07F(7)(c).
Disinfectant Residual | MRDL (mg/l) |
Chlorine 4.0 (as Cl2). | |
Chloramines 4.0 (as Cl2). | |
Chlorine dioxide | 0.8 (as ClO2). |
Notwithstanding the MRDLs in 310 CMR 22.07E(2), systems may increase residual Disinfectant levels in the Distribution System of chlorine or chloramines (but not chlorine dioxide) to a level and for a time necessary to protect public health, to address specific microbiological contamination problems caused by circumstances including, but not limited to, distribution line breaks, storm run-off events, source water contamination events, or cross connection events.
Disinfection Byproduct | Best Available Technology |
TTHM | Enhanced Coagulation or Enhanced Softening or GAC10, with chlorine as the primary and residual Disinfectant. |
HAA5 | Enhanced Coagulation or Enhanced Softening or GAC10, with chlorine as the primary and residual Disinfectant. |
Bromate | Control of ozone treatment process to reduce production of bromate. |
Chlorite | Control of treatment processes to reduce Disinfectant demand and control of Disinfection treatment processes to reduce Disinfectant levels. |
Disinfection byproduct | Best Available Technology |
Total Trihalomethanes (TTHM) and Haloacetic (Acids Five) (HAA5). | Enhanced Coagulation or Enhanced Softening, plus GAC10; or nanofiltration with a molecular weight cutoff <=1000 Daltons; or GAC20 |
Disinfection Byproduct | Best Available Technology |
Total Trihalomethanes (TTHM) and Haloacetic (Acids Five) (HAA5). | Systems serving >=10,000: Improved Distribution System and storage tank management to reduce residence time, plus the use of chloramines for disinfectant residual maintenance |
Systems serving <10,000: Improved Distribution System and storage tank management to reduce residence time. |
APPROVED METHODS FOR DISNFECTION BYPRODUCT COMPLIANCE MONITORING
Contaminant and methodology1 | EPA method | Standard Method SM online9 ASTM method3 | ||
TTHM P&T/GC/ElCD& PID P&T/GC/MS LLE/GC/ECD | 502.24 524.2, 524.310, 524.415, 551.1 | |||
HAA5 LLE (diazomethane)/GC/ECD SPE (acidic methanol)/GC/ECD LLE (acidic methanol)/GC/ECD Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS) HAA5 LLE(diazomethane)/GC/ECD SPE | -------------- 552.15 552.2, 552.3 | 6251 B2, 5, 11 | 6251 B-94 | |
Bromate Ion chromatography Ion chromatography & post column reaction IC/ICP-MS Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS) Chemically Suppressed Ion Chromatography Electrolytically Suppressed Ion Chromatography | 300.1, 302.06, 13 317.0 Rev. 2.06, 326.0 6 321.86,7 557 6, 12 | ---------------- | ---------------- | D 6581-003 D6581-08A14 D6581-08B14 |
Chlorite Amperometric titration Spectrophotometry Ion chromatography Chemically Suppressed Ion Chromatography Electrolytically Suppressed Ion Chromatography | ------------- 327.0 Rev 1.18 300.0, 300.1, 317.0 Rev 2.0, 326.0 | 4500-ClO2 E2, 8 ----------------- ------------------- | 4500-ClO2 E-008 ---------------- | D 6581-003 D 6581-08 A14 D 6581-08 B14 |
Chlorite - daily monitoring as prescribed in 310 CMR 22.07E(7)(b)2.a.i Amperometric Titration | 4500-ClO2 E11 |
1 P&T = purge and trap; GC = gas chromatography; ElCD = electrolytic conductivity detector; PID= photoionization detector; MS = mass spectrometer; LLE = liquid/liquid extraction; ECD = electron capture detector; SPE = solid phase extraction; IC = ion chromatography, ICP-MS=inductively coupled plasma/mass spectrometer.
2 19th and 20th editions of Standard Methods for the Examination of Water and Wastewater, 1995 and 1998, respectively, American Public Health Association; either of these editions may be used.
3 Annual Book of ASTM Standards, 2001 or any year containing the cited version of the method, Vol 11.01.
4 If TTHMs are the only analytes being measured in the sample, then a PID is not required.
5 The samples must be extracted within 14 days of sample collection.
6 Ion chromatography & post column reaction or IC/ICP-MS must be used for monitoring of bromate for purposes of demonstrating eligibility of reduced monitoring, as prescribed in 310 CMR 22.07E(7)(b)3.b.
7 Samples must be preserved at the time of sampling with 50 mg ethylenediamine (EDA)/L of sample and must be analyzed within 28 days.
8 Amperometric titration may be used for routine daily monitoring of chlorite at the entrance to the Distribution System, as prescribed in 310 CMR 22.07E(7)(b)2.a.i. Ion chromatography shall be used for routine monthly monitoring of chlorite and additional monitoring of chlorite in the Distribution System, as prescribed in 310 CMR 22.07E(7)(b)2.a.ii. and (b)2.b.
9 The Standard Methods Online version that is approved is indicated by the last two digits in the method number which is the year of approval by the Standard Method Committee. Standard Methods Online are available at http://www.standardmethods.org.
10 EPA Method 524.3, Version 1.0 Measurement of Purgeable Organic Compounds in Water by Capillary Column Gas Chromatography/Mass Spectrometry, June 2009. EPA 815-B-09-009. Available at http://epa.gov/safewater/methods/analyticalmethods_ogwdw.html.
11 Standard Methods for the Examination of Water and Wastewater, 21st edition (2005). Available from American Public Health Association, 800 I Street, NW., Washington, DC 20001-3710.
12 EPA Method 557. Determination of Haloacetic Acids, Bromate, and Dalapon in Drinking Water by Ion Chromatography Electrospray Ionization Tandem Mass Spectrometry (IC-ESI-MS/MS), August 2009. EPA 815-B-09-012. Available at http://epa.gov/safewater/methods/analyticalmethods_ogwdw.html.
13 EPA Method 302.0. Determination of Bromate in Drinking Waters using Two-dimensional Ion Chromatography with Suppressed Conductivity Detection, September 2009. EPA 815-B-09-014. Available at http://epa.gov/safewater/methods/analyticalmethods_ogwdw.html.
14 Available from ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 or http://astm.org. The methods listed are the only alternative versions that may be used.
15 EPA Method 524.4, Version 1.0. Measurement of Purgeable Organic Compounds in Water by Gas Chromatography/Mass Spectrometry using Nitrogen Purge Gas, May 2013. EPA 815-R-13-002. Available at http://water.epa.gov/drink.
APPROVED METHODS FOR DISINFECTANT RESIDUAL COMPLIANCE MONITORING
Methodology | Standard Method (19th, 20th or 21st editions) | SM Online2 | EPA method | ASTM Method | Residual Measured 1 | |||
Free C12 | Combined C12 | Total C12 | C12 O2 | |||||
Amperometric Titration | 4500-Cl D | 4500-Cl D-00 | D 1253-86 (96), 03, D 1253-084 | X | X | X | ||
Low Level Amperometric | 4500-Cl E | 4500-Cl | X | |||||
Titration | E-00 | |||||||
DPD Ferrous Titrimetric | 4500-Cl F | 4500-Cl F-00 | X | X | X | |||
DPD Colorimetric | 4500-Cl G | 4500-Cl G-00 | X | X | X | |||
Syringaldazine (FACTS) | 4500-Cl H | 4500-Cl H-00 | X | |||||
Iodometric Electrode | 4500-Cl I | 4500-Cl I-00 | X | |||||
DPD | 4500-ClO2 D | X | ||||||
Amperometric Method II | 4500-ClO2 E | 4500-Cl O2 E-00 | X | |||||
Lissamine Green | 327.0 | X | ||||||
Spectrophotometric | Rev 1.1 | |||||||
Amperometric Sensor - | X | X | ||||||
ChloroSense5 | ||||||||
On-line Chlorine Analyzer | 334.06 | X | X |
1 X indicates method is approved for measuring specified Disinfectant residual. Free chlorine or total chlorine may be measured for demonstrating compliance with the chlorine MRDL and combined chlorine, or total chlorine may be measured for demonstrating compliance with the chloramine MRDL.
2 The Standard Methods Online version that is approved is indicated by the last two digits in the method number which is the year of approval by the Standard Method Committee. Standard Methods Online are available at http://www.standardmethods.org.
3 Cl2 = Chlorine, ClO2 = Chlorine Dioxide.
4 Available from ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959 or http://astm.org. The methods listed are the only alternative versions that may be used.
5 ChloroSense. Measurement of Free and Total Chlorine in Drinking Water by Palintest ChloroSense, September 2009. Available at http://www.nemi.gov or from Palintest Ltd, 21 Kenton Lands Road, P.O. Box 18395, Erlanger, KY 41018.
6 EPA Method 334.0. Determination of Residual Chlorine in Drinking Water Using an On-Line Chlorine Analyzer, August 2009. EP A 815-B-09-013. Available at http://epa.gov/safewater/methods/analyticalmethods_ogwdw.html.
Routine Monitoring Frequency for TTHM and HAA5
Type of system | Minimum monitoring frequency | Sample location in the Distribution System |
Systems using Surface Water or Groundwater Under the Direct Influence of Surface Water serving at least 10,000 persons. | Four water samples per quarter per treatment plant. | At least 25% of all samples collected each quarter at locations representing maximum residence time. Remaining samples taken at locations representative of at least average residence time in the Distribution System and representing the entire Distribution System, taking into account number of persons served, different sources of water, and different treatment methods.1 |
Systems using Surface Water or Groundwater Under the Direct Influence of Surface Water serving from 500 to 9,999 persons. | One water sample per quarter per treatment plant. | Locations representing maximum residence time.1 |
Systems using Surface Water or Groundwater Under the Direct Influence of Surface Water serving fewer than 500 persons. | One sample per year per treatment plant during August. | Locations representing maximum residence time.1 If the sample (or average of annual samples, if more than one sample is taken) exceeds the MCL, the system shall increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the Distribution System, until the system meets reduced monitoring criteria in 310 CMR 22.07E(7)(b)1.d. |
Systems using only groundwater not under direct influence of surface water using chemical Disinfectant and serving at least 10,000 persons. | One water sample per quarter per treatment plant.2 | Locations representing maximum residence time.1 |
Systems using only groundwater not under direct influence of surface water using chemical Disinfectant and serving fewer than 10,000 persons. | One sample per year per treatment plant during August.2 | Locations representing maximum residence time.1 If the sample (or average of annual samples, if more than one sample is taken) exceeds the MCL, the system shall increase monitoring to one sample per treatment plant per quarter, taken at a point reflecting the maximum residence time in the Distribution System, until the system meets reduced monitoring criteria in 310 CMR 22.07E(7)(b)1.d. |
1 If a system elects to sample more frequently than the minimum required, at least 25% of all samples collected each quarter (including those taken in excess of the required frequency) shall be taken at locations that represent the maximum residence time of the water in the Distribution System. The remaining samples shall be taken at locations representative of at least average residence time in the Distribution System.
2 Multiple wells drawing water from a single aquifer may be considered one treatment plant for determining the minimum number of samples required, with prior Department approval in accordance with criteria developed under 310 CMR 22.07E(7)(a)2.
Reduced Monitoring Frequency for TTHM and HAA5
If you are a . . . | You may reduce monitoring if you have monitored at least one year and your . . | To this level |
System using Surface Water or Groundwater Under the Direct Influence of Surface Water serving at least 10,000 persons which has a source water annual average TOC level, before any treatment, <= 4.0 mg/l. | TTHM annual average <= 0.040 mg/l and HAA5 annual average <= 0.030 mg/l. | One sample per treatment plant per quarter at Distribution System location reflecting maximum residence time. |
System using Surface Water or Groundwater under the Direct Influence of Surface Water serving from 500 to 9,999 persons which has a source water annual average TOC level, before any treatment, <= 4.0 mg/l. | TTHM annual average <= 0.040 mg/l and HAA5 annual average <= 0.030 mg/l. | One sample per treatment plant per year at Distribution System location reflecting maximum residence time during August. NOTE: Any system using Surface Water or Groundwater under the Direct Influence of Surface Water serving fewer than 500 persons may not reduce its monitoring to less than one sample per treatment plant per year. |
System using only groundwater not under direct influence of surface water using chemical Disinfectant and serving at least 10,000 persons. | TTHM annual average<= 0.040 mg/l and HAA5 annual average <= 0.030 mg/l. | One sample per treatment plant per year at Distribution System location reflecting maximum residence time during August. |
System using only groundwater not under direct influence of surface water using chemical Disinfectant and serving fewer than 10,000 persons. | TTHM annual average <= 0.040 mg/l and HAA5 annual average <= 0.030 mg/l for two consecutive years OR TTHM annual average <= 0.020 mg/l and HAA5 annual average <= 0.015 mg/l for one year. | One sample per treatment plant per three year monitoring cycle at Distribution System location reflecting maximum residence time during August, with the three-year cycle beginning on January 1st following the quarter in which system qualifies for reduced monitoring. |
If you are a... | You shall report...1 |
1. System monitoring for TTHM and HAA5 under the requirements of 310 CMR 22.07E(7)(b) on a quarterly or more frequent basis. | a. The number of samples taken during the last quarter. b. The location, date, and result of each sample taken during the last quarter. c. The arithmetic average of all samples taken in the last quarter. d. The annual arithmetic average of the quarterly arithmetic averages of 310 CMR 22.07(9)(b)1.c. for the last four quarters. e. Whether, based on 310 CMR 22.07E(8)(b)1., the MCL was violated. |
2. System monitoring for TTHM and HAA5 under the requirements of 310 CMR 22.07E(7)(b) less frequently than quarterly (but at least annually). | a. The number of samples taken during the last year. b. The location, date, and result of each sample taken during the last monitoring period. c. The arithmetic average of all samples taken over the last year. d. Whether, based on 310 CMR 22.07E(8)(b)1., the MCL was violated. |
3. System monitoring for TTHM and HAA5 under the requirements of 310 CMR 22.07E(7)(b) less frequently than annually. | a. The location, date, and result of the last sample taken. b. Whether, based on 310 CMR 22.07E(8)(b)1., the MCL was violated. |
4. System monitoring for chlorite under the requirements of 310 CMR 22.07E(7)(b) | a. The number of entry point samples taken each month for the last three months. b. The location, date, and result of each sample (both entry point and Distribution System) taken during the last quarter. c. For each month in the reporting period, the arithmetic average of all samples taken in each three sample set taken in the Distribution System. d. Whether, based on 310 CMR 22.07E(8)(b)3., the MCL was violated, in which month, and how many times it was violated each month. |
5. System monitoring for bromate under the requirements of 310 CMR 22.07E(7)(b). | a. The number of samples taken during the last quarter. b. The location, date, and result of each sample taken during the last quarter. c. The arithmetic average of the monthly arithmetic averages of all samples taken in the last year. d. Whether, based on 310 CMR 22.07E(8)(b)2., the MCL was violated. |
1 The Department may choose to perform calculations and determine whether the MCL was violated.
If you are a... | You shall report...1 |
1. System monitoring for chlorine or chloramines under the requirements of 310 CMR 22.07E(7)(c). | a. The number of samples taken during each month of the last quarter. b. The monthly arithmetic average of all samples taken in each month for the last 12 months. c. The arithmetic average of the monthly averages for the last 12 months. d. Whether, based on 310 CMR 22.07E(8)(c)1., the MRDL was violated. |
2. System monitoring for chlorine dioxide under the requirements of 310 CMR 22.07E(7)(c). | a. The dates, results, and locations of samples taken during the last quarter. b. Whether, based on 310 CMR 22.07E(8)(c)2., the MRDL was violated. c. Whether the MRDL was exceeded in any two consecutive daily samples and whether the resulting violation was acute or nonacute. |
1 The Department may choose to perform calculations and determine whether the MRDL was exceeded or violated.
If you are a . . . | You shall report . . .1 |
1. System monitoring monthly or quarterly for TOC under the requirements of 310 CMR 22.07E(7)(d) and required to meet the Enhanced Coagulation or Enhanced Softening requirements in 310 CMR 22.07E(10)(b)2. or (b)3. | a. The number of paired (source water and treated water) samples taken during the last quarter. b. The location, date, and result of each paired sample and associated alkalinity taken during the last quarter. c. For each month in the reporting period that paired samples were taken, the arithmetic average of the percent reduction of TOC for each paired sample and the required TOC percent removal. d. Calculations for determining compliance with the TOC percent removal requirements, as provided in 310 CMR 22.07E(10)(c)1. e. Whether the system is in compliance with the Enhanced Coagulation or Enhanced Softening percent removal requirements in 310 CMR 22.07E(10)(b) for the last four quarters. |
1 The Department may choose to perform calculations and determine whether the Treatment Technique was met.
If you are a . . . | You shall report . . .1 |
2. System monitoring monthly or quarterly for TOC under the requirements of Sec. 310 CMR 22.07E(7)(d) and meeting one or more of the alternative compliance criteria in 310 CMR 22.07E(10)(a)2. or (a)3. | a. The alternative compliance criterion that the system is using. b. The number of paired samples taken during the last quarter. c. The location, date, and result of each paired sample and associated alkalinity taken during the last quarter. d. The running annual arithmetic average based on monthly averages (or quarterly samples) of source water TOC for systems meeting a criterion in 310 CMR 22.07E(10)(a)2.a. or (a)2.c. or of treated water TOC for systems meeting the criterion in 310 CMR 22.07E(10)(a)2.b. e. The running annual arithmetic average based on monthly averages (or quarterly samples) of source water SUVA for systems meeting the criterion in 310 CMR 22.07E(10)(a)2.e. or of treated water SUVA for systems meeting the criterion in 310 CMR 22.07E(10)(a)2.f. f. The Running Annual Average of source water alkalinity for systems meeting the criterion in 310 CMR 22.07E(10)(a)2.c. and of treated water alkalinity for systems meeting the criterion in 310 CMR 22.07E(10)(a)3.a. g. The Running Annual Average for both TTHM and HAA5 for systems meeting the criterion in 310 CMR 22.07E(10)(a)2.c. or (a)2.d. h. The Running Annual Average of the amount of magnesium hardness removal (as CaCO3, in mg/l) for systems meeting the criterion in 310 CMR 22.07E(10)(a)3.b. i. Whether the system is in compliance with the particular alternative compliance criterion in 310 CMR 22.07E(10)(a)2. or (a)3. |
1 The Department may choose to perform calculations and determine whether the Treatment Technique was met.
Step 1 Required Removal of TOC by Enhanced Coagulation and Enhanced Softening for Systems Using Surface Water or Groundwater Under the Direct Influence of Surface Water and Using Conventional Treatment1,2 | |||
Source-water TOC, mg/l | Source-water alkalinity, mg/l as CaCO3 | ||
0-60 | > 60-120 | > 1203 | |
>2.0-4.0 | 35.0 % | 25.0 % | 15.0 % |
>4.0-8.0 | 45.0 % | 35.0 % | 25.0 % |
>8.0 | 50.0 % | 40.0 % | 30.0 % |
1 Systems meeting at least one of the conditions in 310 CMR 22.07E(10)(a)2. are not required to operate with Enhanced Coagulation.
2 Softening systems meeting one of the alternative compliance criteria in 310 CMR 22.07E(10)(a)3. are not required to operate with Enhanced Softening.
3 Systems practicing softening shall meet the TOC removal requirements in this column.
Enhanced Coagulation Step 2 Target pH | |
Alkalinity (mg/l as CaCO3) | Target pH |
0-60 | 5.5 |
>60-120 | 6.3 |
>120-240 | 7.0 |
>240 | 7.5 |
310 CMR 22.07E