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 Code of Federal Regulations (Last Updated: July 5, 2024)
 Title 40 - Protection of Environment
 Chapter I - Environmental Protection Agency
 SubChapter D - Water Programs
 Part 141 - National Primary Drinking Water Regulations
 Subpart M - Information Collection Requriements (ICR) for Public Water Systems

  § 141.142 - Disinfection byproduct and related monitoring.  

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  • (a) Monitoring requirements. Samples taken under the provisions of this section shall be taken according to the procedures described in the “ICR Sampling Manual,” EPA 814-B-96-001, April 1996. If a treatment plant configuration results in two required sampling points from any table in this section when in fact it is a single location, duplicate analyses are not required for the same location and time. A PWS that uses purchased finished water shall determine whether any monitoring of treatment plant influent is required under paragraphs (a) (2) through (5) of this section because of certain treatment (e.g., use of hypochlorite or chlorine dioxide) of the water provided by the selling PWS.

    (1) A PWS shall obtain a complete set of samples at the frequency and location noted in tables 1a and 1b of this section for treatment plants required to test under § 141.141(b) of this subpart. Samples shall be taken according to the sampling plan approved under the provisions of paragraph (c)(2)(ii) of this section.

    (i) Samples of finished water shall be collected at a point after which all treatment processes for a particular treatment plant are complete (including the clearwell and final point of chlorination) and before the distribution system begins. A PWS that purchases finished water shall collect a sample before additional disinfectant is added to the purchased finished water. A PWS shall collect a sample of purchased finished water only if the PWS redisinfects the purchased finished water. A sample of finished water is a sample representing the final product water from a particular treatment plant.

    (ii) A sample of treatment plant influent for a PWS that treats untreated water shall be taken at a location at the upstream end of a treatment plant where waters from all intakes are blended prior to any treatment or chemical addition. For treatment plants that have multiple intakes and add chemicals at the intake, the sample of treatment plant influent shall be a flow proportional composite of intake samples collected before chemical addition and before pretreatment. If the intakes are expected to have the same source water quality, one representative intake sample may be taken. If a disinfectant is added at or before the intake (e.g., for zebra mussel control), the sample shall be taken in the vicinity of the intake so that the sample is not contaminated by the disinfectant. A sample of treatment plant influent for a PWS that treats purchased finished water is taken at a location just before the purchased finished water is treated. An intake sample is collected after the intake but before blending with waters from other intakes and before addition of chemicals or any treatment.

    Table 1a.—Monthly Monitoring Requirements for Treatment PlantsSampling pointMonthly analyses 1Treatment plant influent for non-finished water pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, TOC, UV 254, Bromide, Ammonia.Treatment plant influent for purchased finished water 2pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, TOC, UV 254, Disinfectant residual 3.Before first point of oxidant addition Chlorine demand test.Washwater return between washwater treatment plant and point of addition to process train 4pH, Alkalinity, Turbidity, Temperature, Calcium and Total hardness, TOC, UV 254, Bromide, Ammonia, Disinfectant residual 3 if disinfectant is used.Additional water sources added to process train after treatment plant influent. The sample point is before additional water is blended with the process train pH, Alkalinity, Turbidity, Temperature, Calcium and Total hardness, TOC, UV 254, Bromide, Ammonia, Disinfectant residual 3 if disinfectant is used.Before Filtration pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, TOC, and UV 254.After Filtration pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, TOC, and UV 254.Before each Point of Disinfection 5pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, TOC, and UV 254.After every unit process that is downstream from the addition of chlorine or chloramines Disinfectant Residual 3.Finished water sample point (Plant effluent) pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, TOC, UV 254, Disinfectant Residual 3.Entry point to distribution system 6pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, TOC, UV 254, Disinfectant Residual 3.1 TOC: total organic carbon. UV 254: absorbance of ultraviolet light at 254 nanometers.2 Samples of purchased finished water shall be taken prior to addition of any more disinfectant.3 Free chlorine residual and total chlorine residual shall be measured in treatment systems using free chlorine. Total chlorine residual, but not free chlorine residual, shall be measured in treatment systems using chloramines as the residual disinfectant.4 Washwater return shall be sampled prior to blending with the process train.5 For utilities using ozone or chlorine dioxide, Tables 4 and 5, respectively, of this section, show additional monitoring requirements at this sampling point. Addition of ammonia for the purpose of converting free chlorine to chloramines is considered a point of disinfectant addition. PWSs that disinfect just before filtration may use the “before filtration” sampling point analytical results to meet the monitoring requirement for this point.6 Entry point to distribution system only required for treatment plants that blend finished water with finished water from other treatment plant(s) prior to entry point of distribution system. For most treatment plants, the finished water sample point and the entry point to the distribution system are the same. Table 1b.—Quarterly Monitoring Requirements for Treatment PlantsSampling pointQuarterly analyses1Treatment plant influent for non-finished waterTOX.Treatment plant influent for purchased finished waterTHM4, HAA67, HAN, CP, HK, CH, TOX.Washwater Return between washwater treatment plant and point of addition to process trainTOX.After filtration if disinfectant is applied at any point in the treatment plant prior to filtrationTHM4, HAA67, HAN, CP, HK, CH, TOX.Finished water sample point (Plant Effluent)THM4, HAA67, HAN, CP, HK, CH, TOX.Entry point to distribution system2THM4, HAA67, HAN, CP, HK, CH, TOX.SDS3THM4, HAA67, HAN, CP, HK, CH, TOX, pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, Disinfectant Residual5.Four monitoring points in distribution system4,6THM4, HAA67, HAN, CP, HK, CH, TOX, pH, Alkalinity, Turbidity, Temperature, Calcium and Total Hardness, Disinfectant Residual5.1 TOC: total organic carbon. THM4: trihalomethane (four). HAA6: haloacetic acids (six). HAN: Haloacetonitriles. CP: chloropicrin. HK: haloketones. CH: chloral hydrate. TOX: total organic halide. For THM4, HAA6, HAN, and HK, analytical results for individual analytes shall be reported.2 Entry point to distribution system only required for treatment plants that blend finished water with finished water from other treatment plant(s) prior to entry point of distribution system. For most treatment plants, the finished water sample point and the entry point to the distribution system are the same.3 Simulated Distribution System (SDS) sample shall be collected at the finished water sampling point (or entry point to distribution system if finished water from two or more plants are blended prior to entering the distribution system) and analyzed using the method specified in § 141.142. PWSs using purchased finished water are not required to take an SDS sample at treatment plants that use only purchased finished water.4 For each treatment plant, one distribution system equivalent sample location (known as DSE) shall be chosen to correspond to the SDS sample, one sample location shall be chosen to be representative of maximum residence time for the treatment plant, and the remaining two sample locations shall be representative of the average residence time in the distribution system for the treatment plant. PWSs using purchased finished water shall take three samples representing the average residence time in the distribution system for the treatment plant and one representing the maximum residence time for the treatment plant (no DSE sample required).5 Free chlorine residual and total chlorine residual shall be measured in treatment systems using free chlorine. Total chlorine residual, but not free chlorine residual, shall be measured in treatment systems using chloramines as the residual disinfectant.6 A PWS may use TTHM compliance monitoring locations and analytical results under § 141.30 of this part to the extent that such locations and analytical results are consistent with the requirements of this section.7 PWSs are encouraged to also analyze for the additional haloacetic acids bromodichloro-, chlorodibromo-, and tribromo-acetic acid, and report the results as part of the reports specified in paragraph (c)(1) of this section.

    (2) Additional requirements for PWSs using chloramines. For each treatment plant that uses chloramines for treatment or disinfection residual maintenance, a PWS shall also conduct the additional sampling identified in table 2 of this section. A PWS shall send samples of cyanogen chloride taken under the provisions of this paragraph for analysis to EPA, following the procedures contained in the “ICR Sampling Manual,” EPA 814-B-96-001, April 1996.

    Table 2.—Additional Quarterly Monitoring for Treatment Plants Using ChloraminesSampling pointQuarterly analysesTreatment plant influent for purchased finished water 1Cyanogen Chloride2.Finished water sample point (plant effluent) Cyanogen Chloride2.Distribution system sample point representing a maximum residence time in distribution system relative to the treatment plant Cyanogen Chloride2.1 Applicable only when wholesale water provider is using chloramines.2 EPA shall provide all analytical results to the PWS. The PWS shall report all results in its monthly report.

    (3) Additional requirements for PWSs using hypochlorite solutions. For each treatment plant that uses hypochlorite solutions for treatment or disinfection residual maintenance, a PWS shall also conduct the additional sampling identified in table 3 of this section.

    Table 3.—Additional Quarterly Monitoring for Treatment Plants Using Hypochlorite SolutionsSampling pointQuarterly analysesTreatment plant influent for non-finished water Chlorate.Treatment plant influent for purchased finished water 1Chlorate.Hypochlorite Stock Solution pH, Temperature, Free Residual Chlorine, Chlorate.Finished Water Sample Point (Plant Effluent) Chlorate.1 Applicable only when wholesale water provider is using hypochlorite solutions.

    (4) Additional requirements for PWSs using ozone. For each treatment plant that uses ozone for treatment, a PWS shall also conduct the additional sampling identified in tables 4a and 4b of this section. A PWS shall collect samples for bromate taken under the provisions of this paragraph in duplicate, with the PWS analyzing one aliquot and submitting the other aliquot for analysis to EPA, following the procedures contained in the “ICR Sampling Manual,” EPA 814-B-96-001, April 1996. A PWS shall submit samples for aldehydes taken under the provisions of this paragraph for analysis to EPA, following the procedures contained in the “ICR Sampling Manual,” EPA 814-B-96-001, April 1996.

    Table 4a.—Additional Monthly Monitoring for Treatment Plants Using OzoneSampling pointMonthly analysesOzone Contactor Influent Bromide, bromate 2,3, and ammonia.Each Ozone Contact Chamber Effluent 1Ozone residual.Ozone Contactor Effluent Bromate2.Finished Water Sample Point (Plant Effluent) Bromate2.1 Each ozone contactor can be subdivided into its contact chambers. Measure ozone residual in effluent of all contact chambers until <0.05 mg/l is measured in two consecutive chambers.2 EPA shall provide all analytical results to the PWS. The PWS shall report all results in its monthly report.3PWSs are not required to analyze a bromate sample at this location. However, PWSs are still required to submit a sample to EPA for analysis. Table 4b.—Additional Quarterly Monitoring for Treatment Plants Using OzoneSampling pointQuarterly analysesOzone Contactor Influent Aldehydes 1 and AOC/BDOC 2.Ozone Contactor Effluent Aldehydes 1 and AOC/BDOC 2.Finished Water Sample Point (Plant Effluent) Aldehydes 1 and AOC/BDOC 2.1 EPA shall measure the following aldehydes: formaldehyde, acetaldehyde, propanal, butanal, pentanal, glyoxal, and methyl glyoxal. EPA may analyze for other aldehydes. EPA shall provide all analytical results to the PWS. The PWS shall report all results in its monthly report.2 Analysis and submission of data for both assimilable organic carbon (AOC) and biodegradable organic carbon (BDOC) are optional. Analytical methods for AOC and BDOC are listed in “DBP/ICR Analytical Methods Manual,” EPA 814-B-96-002, April 1996.

    (5) Additional sampling requirements for PWSs using chlorine dioxide. For each treatment plant that uses chlorine dioxide for treatment or disinfection residual maintenance, a PWS shall also conduct the additional sampling identified in tables 5a and 5b of this section. A PWS shall collect samples for bromate taken under the provisions of this paragraph in duplicate, with the PWS analyzing one aliquot and submitting the other aliquot for analysis to EPA, following the procedures contained in the “ICR Sampling Manual,” EPA 814-B-96-001, April 1996. A PWS shall submit samples for aldehydes taken under the provisions of this paragraph for analysis to EPA, following the procedures contained in the “ICR Sampling Manual,” EPA 814-B-96-001, April 1996.

    Table 5a.—Additional Monthly Monitoring for Treatment Plants Using Chlorine DioxideSampling pointMonthly analysesTreatment plant influent for purchased finished water 1Chlorine Dioxide Residual, Chlorite, Chlorate.Before first chlorine dioxide application Chlorate, bromate 2,3.Before application of ferrous salts, sulfur reducing agents, or GAC Chlorine Dioxide Residual, Chlorite, Chlorate, pH.Finished water sample point (plant effluent) Chlorine Dioxide Residual, Chlorite, Chlorate, Bromate 2.Three distribution system sampling points (1 near first customer, 1 in middle of distribution system, and 1 representative of maximum residence time in the distribution system) Chlorine Dioxide Residual, Chlorite, Chlorate, pH, and Temperature.1 Applicable only when wholesale water provider is using chlorine dioxide.2 EPA shall provide all analytical results to the PWS. The PWS shall report all results in its monthly report.3 PWSs are not required to analyze a bromate sample at this location. However, PWSs are still required to submit a sample to EPA for analysis. Table 5b.—Additional Quarterly Monitoring for Treatment Plants Using Chlorine DioxideSampling pointQuarterly analysesBefore First Chlorine Dioxide Application Aldehydes 1 and AOC/BDOC 2.Before First Point of Downstream Chlorine/Chloramine Application After Chlorine Dioxide Addition Aldehydes 1 and AOC/BDOC 2.Finished Water Sample Point (Plant Effluent) Aldehydes 1 and AOC/BDOC 2.1EPA shall measure the following aldehydes: formaldehyde, acetaldehyde, propanal, butanal, pentanal, glyoxal, and methyl glyoxal. EPA may analyze for other aldehydes. EPA shall provide all analytical results to the PWS. The PWS shall report all results in its monthly report.2 Analysis and submission of data for both assimilable organic carbon (AOC) and biodegradable organic carbon (BDOC) are optional. Analytical methods for AOC and BDOC are listed in “DBP/ICR Analytical Methods Manual,” EPA 814-B-96-002, April 1996.

    (6) Additional requirements. A PWS shall also report the applicable information in tables 6a through 6e of this section. A PWS is required to provide the information in paragraphs (a)(6) (i) through (iii) of this section for each unit process listed in table 6c. The PWS may provide the information in paragraphs (a)(6) (iv) and (v) of this section for each unit process listed in table 6c. T10 and T50 tracer studies shall be conducted as specified in “Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources”, appendix C.

    (i) Unit process flow (MGD) at time of sampling.

    (ii) T10 (minutes). A PWS shall determine T10 based on a one-time tracer study in the clearwell of all treatment plants required to conduct microbiological monitoring under the provisions of § 141.141(d) of this subpart. The PWS may use results of a tracer study conducted to meet the requirements of subpart H (Filtration and Disinfection) of this part to meet this requirement. For subsequent T10 determinations, the PWS shall use a flow-proportional interpolation of the clearwell tracer study. For unit processes other than a clearwell, a PWS shall either estimate T10 or use an interpolation of tracer study T10 using multiple flows for each unit process in which a disinfectant residual exists.

    (iii) Chemicals in use at time of sampling. Report chemical name, chemical dose at time of sampling, and measurement formula. Measurement formulas (e.g., mg/l as Aluminum) shall be provided to determine the correct amount of the chemical compound being added.

    (iv) Short circuiting factor (optional). The short circuiting factor is an assumed value for the ratio of T10 to nominal contact time (volume divided by flow).

    (v) T50 (minutes) (optional). T50 should be reported only if based on a tracer study.

    Table 6a.—Public Water System InformationPermanent dataDesign dataMonthly dataPublic Water System:Utility Name
  • Public Water Supply Identification Number (PWSID)
  • Water Industry Data Base (WIDB) Number [Optional]
  • Official Contact Person:
  • Name
  • Mailing Address
  • Phone Number [optional]
  • FAX Number [optional]
  • ICR Contact Person:
  • Name
  • Mailing Address
  • Phone Number [optional]
  • FAX Number [optional]
  • E-Mail Address [optional]
    • Sampling Dates: From (date) To (date).
  • Retail population on day of sampling.
  • Wholesale population on day of sampling.
  • Monthly average Retail flow (MGD).
  • Monthly average Wholesale flow (MGD).
    • Treatment Plant: 1Plant name
  • ICR plant number assigned by EPA 2
  • PWSID number of treatment plant 3
  • State approved (permitted) plant capacity (MGD)
  • Historical minimum water temperature (°C)
  • Installed sludge handling capacity (lb/day)
    • Plant type (e.g., Conventional Filtration, Direct Filtration, In-Line Filtration, Two Stage Softening, Disinfection Only/Groundwater, Other Groundwater treatment) Hours of operation (hours per day)
  • Sludge solids production (lb/day)
  • Percent solids in sludge (%)
    • Process Train:Name Process Train Type (e.g., Conventional Filtration, Direct Filtration, In-Line Filtration, Two Stage Softening, Disinfection Only/Groundwater, Other Groundwater treatment)1 A PWS that operates more than one treatment plant shall report treatment plant information in this table for each treatment plant.2 EPA shall assign ICR plant number after the PWS submits sampling plan.3 PWSID of treatment plant if different from the PWSID reported in “Public Water System”. Table 6b.—Plant Influent InformationPermanent dataMonthly dataWater Resource 1Name of resource: If Reservoir/Lake: Mean Residence Time (days).Type of resource (One of the following):1Flowing stream2Reservoir/Lake3Ground water classified as under the direct influence of surface water (GWUDI)4Ground water5Purchased finished water6Non-Fresh (such as salt water)Intake-Surface Water 2Location of intake: 3Flow on day of sampling (MGD).Latitude (deg/min/sec)Longitude (deg/min/sec)Hydrologic unit code (8 digit), if known 4Stream Reach Code (3 digit) (if known)River mile number (mile) (if known)Is watershed control practiced? (yes/no)Intake-Ground Water 5 6Location of intake: Flow on day of sampling (MGD).Latitude (deg/min/sec)Longitude (deg/min/sec)Hydrological unit code (8 digit), if known 4Is wellhead protection practiced? (yes/no)Intake-Purchased Finished Water 7Name of supplying utility Flow on day of sampling (MGD).PWSID of supplying utilityPlant Influent 8Monthly average flow (MGD).Flow at time of sampling (MGD).1 Each treatment plant shall have at least one water resource. Each water resource shall have at least one intake. A treatment plant that uses more than one water resource shall report water resource information in this table for each water resource.2 Intake-Surface Water describes the physical location of an intake structure located in a river, lake, or other surface water resource or, for ground water under the direct influence of surface water, the physical location of a well.3 The location of the intake will allow cross referencing into other data bases containing information on possible contamination threats to the intake.4 The hydrologic unit code will allow cross referencing into other data bases containing information on possible contamination threats to the intake.5 An Intake-Ground Water describes the physical location of a well or well field (if multiple wells draw from a common aquifer.6 A PWS is not required to report information for ground water that is not treated.7 A PWS is required to report information for purchased finished water only if that water is further treated.8 Multiple “Intakes” combine into one “Plant Influent.” Each treatment plant has only one treatment plant influent. The treatment plant influent shall mark the point in the treatment plant where the “Plant Influent” sample shall be collected as described in Tables 1, 2, 3 and 5 of this section. Table 6c.—Unit Process InformationDesign dataMonthly dataPresedimentation Basin 1Tube Settler Brand NameLiquid volume (gallons).Plate Settler Brand NameSurface area (ft2).Baffling type2Projected Tube Settler Surface Area (ft2).Projected Plate Settler Surface Area (ft2).Ozone Contact BasinInformation for the complete ozone contact basin:
  • Type of Ozone Contactor (One of the following)
  • 1Bubble Diffusion
  • 2Turbine
  • Number of Chambers
  • Information for each ozone contact chamber:
  • Chamber sequence number
  • Liquid volume (ft3)
  • Surface area (ft2)
  • Water/Ozone flow regime (one of the following)
  • 1Counter-current
  • 2Co-current
    • Information for the complete ozone contact basin:
  • Ozone CT (mg min/l).10
  • Ozone Giardia Inactivation (logs).
  • Ozone Virus Inactivation (logs).
  • Ozone concentration in feed gas (% by weight).
  • Total Ozone Gas Flow Rate to Contactor (SCFM).3
  • Type of feed gas used to generate ozone (one of the following).
  • 1Air.
  • 2Oxygen.
  • Total Ozone Applied Dose (mg/l).
  • Information for each ozone contact chamber:
  • Percent ozone gas flow split to this chamber (%).
  • Hydrogen peroxide dose (mg/l).
    • Washwater Return Point 8Indicate which washwater treatment processes are being used on day of samplingFlow of returned washwater at time of sampling (MGD).
  • 24 hr average flow prior to sampling (MGD).
    • Is there treatment (yes/no):If yes:Plain sedimentation (yes/no)Coagulation/sedimentation (yes/no)Filtration (yes/no)Disinfection (yes/no)Other Treatment (Text)Rapid MixType of mixer (one of the following):Mean velocity gradient “G” (sec‐1).4
  • Liquid volume (gallons).
    • 1Mechanical2Hydraulic3Static4OtherBaffling type 2Flocculation BasinType of mixer (one of the following):Mean velocity gradient “G” (sec‐1) in each stage.4
  • Liquid volume of each stage (gallons).
    • 1Mechanical2HydraulicNumber of stagesBaffling type 2Sedimentation BasinTube settler brand nameLiquid volume (gallons).Plate settler brand nameSurface area (ft2).Baffling type 2Projected tube settler surface area (ft2).Projected plate settler surface area (ft2).Solids Contact ClarifierBrand name:Liquid volume (gallons).
  • Surface area of settling zone (ft2).
  • Projected tube settler surface area (ft2).
  • Projected plate settler surface area (ft2).
    • Type (check all that apply):Rectangular basinUpflowReactor-clarifierSludge blanketTube settler brand namePlate settler brand nameBaffling type 2Adsorption ClarifierBrand NameLiquid volume (gallons).Baffling type 2Surface area (ft2).Dissolved Air FlotationBaffling type 2Liquid volume (gallons).Surface area (ft2).Percent recycle rate (%).Recycle stream pressure (psi).Recarbonation BasinBaffling type 2Liquid volume (gallons).Surface area (ft2).FiltrationMedia Type (one of the following):Liquid volume (gallons).
  • Surface area (ft2).
  • Average filter run time (hr).
    • 1Dual media (Anthracite/Sand)2GAC over sand3Tri media (Anthracite/Sand/Garnet)4Sand5Deep bed monomedia anthracite6Deep bed monomedia GAC7Greensand8OtherDesign depth of GAC (inch)Type and manufacturer of activated carbonDesign media depth (inch)Minimum water depth to top of media (ft)Depth from top of media to top of backwash trough (ft)Slow Sand FiltrationMedia typeSurface area (ft2).Media depthAverage filter run length.Media sizeCleaning method.Diatomaceous Earth FilterEffective DE filter surface (ft2).Precoat (lb/ft2).Bodyfeed (mg/l).Run length (hours).Granular Activated Carbon—Post-Filter AdsorberManufacturer of activated carbonLiquid volume (gallons).Type of activated carbonSurface area (ft2).Carbon volume (ft3).Empty bed contact time (minutes).Operating reactivation frequency (days).MembranesModel name:
  • Type (one of the following):
  • 1 Reverse osmosis
  • 2 Nanofiltration
  • 3 Ultrafiltration
  • 4 Microfiltration
  • 5 Electrodialysis
  • Number of stages
  • Molecular weight cutoff (daltons)
  • Design flux (gpd/ft2)
  • Design pressure (psi)
    • Surface area (ft2).
  • Percent recovery (%).
  • Operating pressure (psi).
  • Operating flux (gpd/ft2).
  • Cleaning method (one of the following)
  • Hydraulic.
  • Chemical.
  • Cleaning frequency (days).
    • Air StrippingPacking height (ft)Horizontal cross-section area (ft2).Design air to water ratio (volume/volume)Air flow (SCFM).3Type of packing (Name)Nominal size of packing (inch)Ion ExchangeResin (Name)Liquid volume (gallons).Resin manufacturerSurface area (ft2).Design exchange capacity (equ/ft3) 3Bed depth (ft)Disinfection Contact Basin 5 6Baffling type 2Liquid volume (gallons).Surface area (ft2).Clearwell 7Baffling type 2Liquid volume (gallons).Minimum liquid volume (gallons)Surface area (ft2).Covered or OpenAdditional Water Sources 9Type of water source:Flow of additional source (MGD).6Purchased Finished waterUntreated ground waterTreated ground waterUntreated surface waterTreated surface waterOtherOther TreatmentPurposeSurface area (ft2) [optional].Liquid Volume (gallons) [optional].1 A reservoir to which oxidants, disinfectants, or coagulants are added is considered a presedimentation basin.2 Baffling type classified as one of the following: 1 (Unbaffled (mixed tank)), 2 (Poor (inlet/outlet only)), 3 (Average (Inlet/Outlet and intermediate)), 4 (Superior (Serpentine)), or 5 (Perfect (Plug flow)). Information on classifying baffling types can be found in “Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources”, Appendix C.3 “SCFM” is standard cubic feet per minute. “Equ/ft3” is equivalents per cubic foot.4 The mean velocity gradient is typically computed as G=square root of (P/uV) where P=power expended, u=viscosity, and V=liquid volume.5 The disinfection contact basin shall have a stable liquid level.6 Disinfection Contact Basin can be used to represent a pipe with a long contact time.7 A clear well may have a variable liquid level.8 The “Washwater Return” shall mark the point in the process train where washwater joins the main flow.9 Additional water sources includes water that is added to the process train after the influent.10 Ozone CT calculated using the procedure contained in “Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources”, Appendix O, 1991.     Table 6d.—Additional Process Train InformationDesign dataMonthly dataDisinfectant AdditionDisinfectants in use at time of sampling.Dose (mg/l).Chemical formula (e.g., mg/l as chlorine).Finished Water Sample Point (Plant Effluent) 1,2Monthly average flow (MGD).Flow at time of sampling (MGD).1 This shall mark the end of a treatment plant.2 Unless the finished water of this treatment plant is blended with finished water from another treatment plant, this point is also the entry point to the distribution system. Table 6e.—Finished Water Distribution InformationDesign dataMonthly dataEntry Point to Distribution System 1Monthly average flow (MGD).Flow at time of sampling (MGD).Wholesale Information 2Name of purchaser Flow at time of sampling (MGD).PWSID of purchaserDistribution SystemTypical maximum residence time (days) Maximum residence time (days).Average residence time (days) Average residence time (days).Design volume of distribution system storage (million gallon) Number of disinfection booster stations in operation at time of sampling:Total surface area of open reservoirs in distribution system storage (ft2) Chlorine.
  • Chloramine.
  • Chlorine dioxide.
  • Range of distribution system disinfectant dosages.
  • Chlorine: High (mg/l) Low (mg/l).
  • Chloramine: High (mg/l) Low (mg/l).
  • Chlorine dioxide: High (mg/l) Low (mg/l).
    • 1 Multiple treatment plants can feed into one entry point to the distribution system. If there is only one treatment plant then “Finished Water Sample Point (Plant Effluent)” and “Entry Point to Distribution System” are the same.2 The supplying public water system shall report “Wholesale Information” for each public water system which purchases finished water.

    (b) Analytical methods. (1) A PWS shall use the methods identified in table 7 of this section for conducting analyses required by this subpart.

    Table 7.—Analytical Methods Approved for Subpart MAnalyteMethodology 140 CFR reference 2EPA methodStandard method 3pH, alkalinity, calcium hardness, temperature § 141.23(k)(1)Turbidity § 141.74(a)(1)Disinfectant residuals: free chlorine, total chlorine, chlorine dioxide, ozone § 141.74(a)(2) 4500-Cl B 9Trihalomethanes: chloroform, bro
  • modichloromethane, dibro
  • mochloromethane, bromoform
    • § 141.24(e) 551.1 4    Haloacetic acids: mono-, di-, and trichloroacetic acids; mono- and dibromoacetic acid; bromochloroacetic acid 552.1, 5 552.2 46251 BChloral hydrate 551.1 4Haloacetonitriles: di- and trichloroacetonitrile; bromochloroacetonitrile; dibromoacetonitrile 551.1 4Haloketones: 1,1-Dichloropropanone; 1,1,1-trichloropropanone 551.1 4Chloropicrin 551.1 4Chlorite 300.0 6Chlorate 300.0 6Bromide 300.0 6Bromate 300.0 6Total Organic Halide (TOX) 5320 BTotal Organic Carbon 5310 B, 5310 C, 5310 DUV absorbance at 254 nm 5910Simulated Distribution System Test (SDS) 5710 CTotal Hardness 2340 B,7 2340 CAmmonia § 136.3, Table 1b 8350.1 64500-NH3 D, 4500-NH3 GChlorine Demand Test 2350 B1 Analyses shall be conducted by using mandatory analytical and quality control procedures contained in “DBP/ICR Analytical Methods Manual”, EPA 814-B-96-002.2 Currently approved methodology for drinking water compliance monitoring is listed in Title 40 of the Code of Federal Regulations in the sections referenced in this column. The 18th and 19th editions of Standard Methods for the Examination of Water and Wastewater, American Public Health Association, 1015 Fifteenth Street NW, Washington, D.C. 20005, are equivalent for the methods cited in these sections. Therefore, either edition may be used.3 Except where noted, all methods refer to the 19th edition of Standard Methods for the Examination of Water and Wastewater, American Public Health Association, 1015 Fifteenth Street NW, Washington, D.C. 20005.4 Analytical method reprinted in “Reprints of EPA Methods for Chemical Analyses Under the Information Collection Rule”, EPA 814-B-96-006. Originally published in “Methods for the Determination of Organic Compounds in Drinking Water—Supplement III,” EPA/600/R-95/131, August 1995, PB95-261616.5 Analytical method reprinted in “Reprints of EPA Methods for Chemical Analyses Under the Information Collection Rule”, EPA 814-B-96-006. Originally published in “Methods for the Determination of Organic Compounds in Drinking Water—Supplement II,” EPA/600/R-92/129, August 1992, PB92-207703.6 Analytical method reprinted in “Reprints of EPA Methods for Chemical Analyses Under the Information Collection Rule”, EPA 814-B-96-006. Originally published in “Methods for the Determination of Inorganic Substances in Environmental Samples,” EPA/600/R-93/100, August 1993, PB94-121811.7 The following methods, cited at § 141.23(k)(1) of this part, can be used to determine calcium and magnesium concentrations for use in conjunction with Standard Method 2340 B: EPA Method 200.7, Standard Method 3111 B, Standard Method 3120 B, or ASTM Method D511-93 B.8 PWSs may use only the automated electrode method from § 136.3, Table 1b.9 Standard Method 4500-Cl B is approved only for determining free chlorine residual concentrations in hypochlorite stock solutions. This method may not be used for any other disinfectant residual analyses.

    (2) Analyses under this section shall be conducted by laboratories that have received approval from EPA to perform sample analysis for compliance with this rule. Laboratories that wish to become approved shall contact EPA in writing at USEPA, Technical Support Division, ICR Laboratory Coordinator, 26 W. Martin Luther King Drive, Cincinnati, OH 45268 not later than November 14, 1996. Requirements for approval are included in “DBP/ICR Analytical Methods Manual”, EPA 814-B-96-002.

    (c) Reporting. (1) A PWS shall report required data and information collected under the provisions of paragraph (a) of this section to EPA, using an EPA-specified computer readable format. A PWS shall submit a monthly report that indicates the analytical results of all samples collected, including quarterly samples taken in that same month, and all process train data. These reports shall be submitted on a diskette no later than the fourth month following sampling. In addition to the information in tables 1 through 6 in paragraph (a) of this section, reports shall include PWSID, ICR plant identification, sample date, analysis date, laboratory identification numbers, analytical methods used, sample identification numbers, quality assurance code, internal standards, surrogate standards, and preserved sample pH, if appropriate.

    (2) Additional Requirements. A PWS shall submit a DBP and related monitoring sampling plan for EPA approval, using software provided by EPA, for each treatment plant specified in § 141.141(b)(2) of this subpart that indicates sampling point locations and monitoring to be conducted at each point, and process treatment train information. This sampling plan shall be submitted to EPA at the same time and on the same diskette as the microbiological sampling plan required by § 141.143(c)(3) and no later than eight weeks after the PWS receives the Notice of ICR Final Applicability Determination from EPA, using the procedure specified in “ICR Sampling Manual”, EPA 814-B-96-001, April 1996.

    (3) All reports required by this section shall be submitted to USEPA (ICR4600), ICR Data Center, Room 1111 East Tower, 401 M Street SW., Washington, DC 20460.

    (4) The PWS shall keep all data for at least three years following data submission to EPA.

    (d) Incorporation by reference. The documents and methods listed in paragraphs (d) (1) and (2) of this section are incorporated by reference for purposes specified in this section. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be inspected at USEPA, Drinking Water Docket (4101), 401 M Street SW., Washington, DC 20460, or at Office of the Federal Register, 800 North Capitol Street, NW., Suite 700, Washington, DC.

    (1) “Standard Methods for the Examination of Water and Wastewater,” 19th edition, 1995. Available from the American Public Health Association, 1015 Fifteenth Street, NW., Washington, DC 20005.

    (2) “Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems using Surface Water Sources”, Appendices C and O, 1991. Available from American Water Works Association, 6666 West Quincy Avenue, Denver, CO 80235.