40 CFR 141.35 – Reporting for unregulated contaminant monitoring results
(a) General applicability. This section applies to any owner or operator of a public water system (PWS) required to monitor for unregulated contaminants under § 141.40(a); such owner or operator is referred to as “you.” This section specifies the information that must be reported to EPA prior to the commencement of monitoring and describes the process for reporting monitoring results to EPA. For the purposes of this section, PWS “population served” is the retail population served directly by the PWS as reported to the Federal Safe Drinking Water Information System (SDWIS/Fed). For purposes of this section, the term “finished” means water that is introduced into the distribution system of a PWS and is intended for distribution and consumption without further treatment, except the treatment necessary to maintain water quality in the distribution system (e.g., booster disinfection, addition of corrosion control chemicals). For purposes of this section, the term “State” refers to the State or Tribal government entity that has jurisdiction over your PWS even if that government does not have primary enforcement responsibility for PWSs under the Safe Drinking Water Act. For purposes of this section, the term “PWS Official” refers to the person at your PWS who is able to function as the official spokesperson for the system’s Unregulated Contaminant Monitoring Regulation (UCMR) activities; and the term “PWS Technical Contact” refers to the person at your PWS who is responsible for the technical aspects of your UCMR activities, such as details concerning sampling and reporting.
(b) Reporting by all systems. You must meet the reporting requirements of this paragraph if you meet the applicability criteria in § 141.40(a)(1) and (2).
(1) Where to submit UCMR reporting requirement information. Some of your reporting requirements are to be fulfilled electronically and others by mail. Information that must be submitted using EPA’s electronic data reporting system must be submitted through: https://www.epa.gov/dwucmr. Documentation that is required to be mailed can be submitted either: To UCMR Sampling Coordinator, USEPA, Technical Support Center, 26 West Martin Luther King Drive (MS 140), Cincinnati, OH 45268; or by email at UCMR_Sampling_Coordinator@epa.gov. In addition, you must notify the public of the availability of unregulated contaminant monitoring data as provided in subpart Q (Public Notification) of this part (40 CFR 141.207). Community Water Systems that detect unregulated contaminants under this monitoring must also address such detections as part of their Consumer Confidence Reports, as provided in subpart O of this part (40 CFR 141.151).
(2) Contacting EPA if your system does not meet applicability criteria or has a status change. If you have received a letter from EPA or your State concerning your required monitoring and your system does not meet the applicability criteria for UCMR established in § 141.40(a)(1) or (2), or if a change occurs at your system that may affect your requirements under UCMR as defined in § 141.40(a)(3) through (5), you must mail or email a letter to EPA, as specified in paragraph (b)(1) of this section. The letter must be from your PWS Official and must include your PWS Identification (PWSID) Code along with an explanation as to why the UCMR requirements are not applicable to your PWS, or have changed for your PWS, along with the appropriate contact information. EPA will make an applicability determination based on your letter and in consultation with the State when necessary. You are subject to UCMR requirements unless and until you receive a letter from EPA agreeing that you do not meet the applicability criteria.
(c) Reporting by large systems. If you serve a population of more than 10,000 people, and meet the applicability criteria in § 141.40(a)(2)(i), you must meet the reporting requirements in paragraphs (c)(1) through (8) of this section.
(1) Contact and zip code information. You must provide contact information by December 31, 2022, and provide updates within 30 days if this information changes. The contact information must be submitted using EPA’s electronic data reporting system, as specified in paragraph (b)(1) of this section, and include the name, affiliation, mailing address, phone number, and email address for your PWS Technical Contact and your PWS Official. In addition, as a one-time reporting requirement, you must report the U.S. Postal Service Zip Code(s) for all areas being served water by your PWS.
(2) Sampling location inventory information. You must provide your inventory information by December 31, 2022, using EPA’s electronic data reporting system, as specified in paragraph (b)(1) of this section. You must submit, verify, or update data elements 1-9 (as defined in Table 1 of paragraph (e) of this section) for each sampling location, or for each approved representative sampling location (as specified in paragraph (c)(3) of this section) regarding representative sampling locations. If this information changes, you must report updates, including new sources, and sampling locations that are put in use before or during the UCMR sampling period, to EPA’s electronic data reporting system within 30 days of the change.
(3) Proposed ground water representative sampling locations. Some systems that use ground water as a source and have multiple entry points to the distribution system (EPTDSs) may propose monitoring at representative entry point(s), rather than monitor at every EPTDS, as follows:
(i) Qualifications. Large PWSs that have EPA- or State-approved representative EPTDS sampling locations from a previous UCMR cycle, or as provided for under 40 CFR 141.23(a)(1), 40 CFR 141.24(f)(1), or 40 CFR 141.24(h)(1), may submit a copy of documentation from your State or EPA that approves your representative sampling plan. PWSs that do not have an approved representative EPTDS sampling plan may submit a proposal to sample at representative EPTDS(s) rather than at each individual EPTDS if: You use ground water as a source; all of your well sources have either the same treatment or no treatment; and you have multiple EPTDSs from the same source (i.e., same aquifer). You must submit a copy of the existing or proposed representative EPTDS sampling plan, as appropriate, at least six months prior to your scheduled sample collection, as specified in paragraph (b)(1) of this section. If changes to your inventory that impact your representative plan occur before or during the UCMR sampling period, you must report updates within 30 days of the change.
(ii) Demonstration. If you are submitting a proposal to sample at representative EPTDS(s) rather than at each individual EPTDS, you must demonstrate that any EPTDS that you propose as representative of multiple wells is associated with a well that draws from the same aquifer as the wells it will represent. The proposed well must be representative of the highest annual volume and most consistently active wells in the representative array. If that representative well is not in use at the scheduled sampling time, you must select and sample an alternative representative well. You must submit the information defined in Table 1, paragraph (e) of this section for each proposed representative sampling location. You must also include documentation to support your proposal that the specified wells are representative of other wells. This documentation can include system-maintained well logs or construction drawings indicating that the representative well(s) is/are at a representative depth, and details of well casings and grouting; data demonstrating relative homogeneity of water quality constituents (e.g., pH, dissolved oxygen, conductivity, iron, manganese) in samples drawn from each well; and data showing that your wells are located in a limited geographic area (e.g., all wells within a 0.5 mile radius) and/or, if available, the hydrogeologic data indicating the ground water travel time between the representative well and each of the individual wells it represents (e.g., all wells within a five-year time of travel delineation). Your proposal must be sent in writing to EPA, as specified in paragraph (b)(1) of this section.
(iii) Approval. EPA or the State (as specified in the Partnership Agreement reached between the State and EPA) will review your proposal and coordinate any necessary changes with you. Your plan will not be final until you receive written approval from EPA, identifying the final list of EPTDSs where you will be required to monitor.
(4) Contacting EPA if your PWS has not been notified of requirements. If you believe you are subject to UCMR requirements, as defined in 40 CFR 141.40(a)(1) and (a)(2)(i), and you have not been contacted by either EPA or your State by April 26, 2022, you must send a letter to EPA, as specified in paragraph (b)(1) of this section. The letter must be from your PWS Official and must include an explanation as to why the UCMR requirements are applicable to your system along with the appropriate contact information. A copy of the letter must also be submitted to the State as directed by the State. EPA will make an applicability determination based on your letter, and in consultation with the State when necessary and will notify you regarding your applicability status and required sampling schedule. However, if your PWS meets the applicability criteria specified in 40 CFR 141.40(a)(2)(i), you are subject to the UCMR monitoring and reporting requirements, regardless of whether you have been contacted by the State or EPA.
(5) Notifying EPA if your PWS cannot sample according to schedule—
(i) General rescheduling notification requirements. Large systems may independently change their monitoring schedules up to December 31, 2022, using EPA’s electronic data reporting system, as specified in paragraph (b)(1) of this section. After this date has passed, if your PWS cannot sample according to your assigned sampling schedule (e.g., because of budget constraints, or if a sampling location will be closed during the scheduled month of monitoring), you must mail or email a letter to EPA, as specified in paragraph (b)(1) of this section, prior to the scheduled sampling date. You must include an explanation of why the samples cannot be taken according to the assigned schedule, and you must provide the alternative schedule you are requesting. You must not reschedule monitoring specifically to avoid sample collection during a suspected vulnerable period. You are subject to your assigned UCMR sampling schedule or the schedule that you revised on or before December 31, 2022, unless and until you receive a letter from EPA specifying a new schedule.
(ii) Exceptions to the rescheduling notification requirements. For ground water sampling, if the second round of sampling will be completed five to seven months after the first sampling event, as specified in Table 2 of § 141.40(a)(4)(i)(B), no notification to EPA is required. If any ground water sampling location will be non-operational for more than one month before and one month after the month in which the second sampling event is scheduled (i.e., it is not possible for you to sample within the five to seven month window), you must notify EPA, as specified in paragraph (b)(1) of this section, explaining why the schedule cannot be met. You must comply with any modified schedule provided by EPA.
(6) Reporting monitoring results. For UCMR samples, you must report all data elements specified in Table 1 of paragraph (e) of this section, using EPA’s electronic data reporting system. You also must report any changes, relative to what is currently posted, made to data elements 1 through 9 to EPA in writing, explaining the nature and purpose of the proposed change, as specified in paragraph (b)(1) of this section.
(i) Electronic reporting system. You are responsible for ensuring that the laboratory conducting the analysis of your unregulated contaminant monitoring samples (your laboratory) posts the analytical results to EPA’s electronic reporting system. You are also responsible for reviewing, approving, and submitting those results to EPA.
(ii) Reporting schedule. You must require your laboratory, on your behalf, to post and approve the data in EPA’s electronic data reporting system, accessible at https://www.epa.gov/dwucmr, for your review within 90 days from the sample collection date (sample collection must occur as specified in 40 CFR 141.40(a)(4)). You then have 30 days from when the laboratory posts and approves your data to review, approve, and submit the data to the State and EPA via the agency’s electronic data reporting system. If you do not electronically approve and submit the laboratory data to EPA within 30 days of the laboratory posting approved data, the data will be considered approved by you and available for State and EPA review.
(7) Only one set of results accepted. If you report more than one set of valid results for the same sampling location and the same sampling event (for example, because you have had more than one laboratory analyze replicate samples collected under § 141.40(a)(5), or because you have collected multiple samples during a single monitoring event at the same sampling location), EPA will use the highest of the reported values as the official result.
(8) No reporting of previously collected data. You cannot report previously collected data to meet the testing and reporting requirements for the contaminants listed in § 141.40(a)(3). All analyses must be performed by laboratories approved by EPA to perform UCMR analyses using the analytical methods specified in Table 1 of § 141.40(a)(3) and using samples collected according to § 141.40(a)(4). Such requirements preclude the possibility of “grandfathering” previously collected data.
(d) Reporting by small systems. If you serve a population of 10,000 or fewer people, and you are notified that you have been selected for UCMR monitoring, your reporting requirements will be specified within the materials that EPA sends you, including a request for contact information, and a request for information associated with the sampling kit.
(1) Contact and zip code information. EPA will send you a notice requesting contact information for key individuals at your system, including name, affiliation, mailing address, phone number and email address. These individuals include your PWS Technical Contact and your PWS Official. You are required to provide this contact information within 90 days of receiving the notice from EPA as specified in paragraph (b)(1) of this section. If this contact information changes, you also must provide updates within 30 days of the change, as specified in paragraph (b)(1) of this section. In addition, as a one-time reporting requirement, you must report the U.S. Postal Service Zip Code(s) for all areas being served water by your PWS.
(2) Sampling location inventory information. You must provide your inventory information by December 31, 2022, using EPA’s electronic data reporting system, as specified in paragraph (b)(1) of this section. If this information changes, you must report updates, including new sources, and sampling locations that are put in use before or during the UCMR sampling period, to EPA’s electronic data reporting system within 30 days of the change, as specified in paragraph (b)(1) of this section. You must record all data elements listed in Table 1 of paragraph (e) of this section on each sample form and sample bottle, as appropriate, provided to you by the UCMR Sampling Coordinator. You must send this information as specified in the instructions of your sampling kit, which will include the due date and return address. You must report any changes made in data elements 1 through 9 by emailing an explanation of the nature and purpose of the proposed change to EPA, as specified in paragraph (b)(1) of this section.
(e) Data elements. Table 1 defines the data elements that must be provided for UCMR monitoring.
Table 1 to Paragraph
| Data element | Definition |
|---|---|
| 1. Public Water System Identification (PWSID) Code | The code used to identify each PWS. The code begins with the standard 2-character postal State abbreviation or Region code; the remaining 7 numbers are unique to each PWS in the State. The same identification code must be used to represent the PWS identification for all current and future UCMR monitoring. |
| 2. Public Water System Name | Unique name, assigned once by the PWS. |
| 3. Public Water System Facility Identification Code | An identification code established by the State or, at the State’s discretion, by the PWS, following the format of a 5-digit number unique within each PWS for each applicable facility (i.e., for each source of water, treatment plant, distribution system, or any other facility associated with water treatment or delivery). The same identification code must be used to represent the facility for all current and future UCMR monitoring. |
| 4. Public Water System Facility Name | Unique name, assigned once by the PWS, for every facility ID ( |
| 5. Public Water System Facility Type | That code that identifies that type of facility as either: CC = Consecutive connection. SS = Sampling station. TP = Treatment plant. OT = Other. |
| 6. Water Source Type | The type of source water that supplies a water system facility. Systems must report one of the following codes for each sampling location: |
| SW = Surface water (to be reported for water facilities that are served entirely by a surface water source during the 12-month period). | |
| GU = Ground water under the direct influence of surface water (to be reported for water facilities that are served all or in part by ground water under the direct influence of surface water at any time during the 12-month sampling period), and are not served at all by surface water during this period. | |
| MX = Mixed water (to be reported for water facilities that are served by a mix of surface water, ground water, and/or ground water under the direct influence of surface water during the 12-month period). | |
| GW = Ground water (to be reported for water facilities that are served entirely by a ground water source during the 12-month period). | |
| 7. Sampling Point Identification Code | An identification code established by the State, or at the State’s discretion, by the PWS, that uniquely identifies each sampling point. Each sampling code must be unique within each applicable facility, for each applicable sampling location (i.e |
| 8. Sampling Point Name | Unique sample point name, assigned once by the PWS, for every sample point ID ( |
| 9. Sampling Point Type Code | A code that identifies the location of the sampling point as: EP = Entry point to the distribution system. |
| 10. Disinfectant Type | All of the disinfectants/oxidants that have been added prior to and at the entry point to the distribution system. Please select all that apply: |
| PEMB = Permanganate. | |
| HPXB = Hydrogen peroxide. | |
| CLGA = Gaseous chlorine. | |
| CLOF = Offsite generated hypochlorite (stored as a liquid form). | |
| CLON = Onsite generated hypochlorite. | |
| CAGC = Chloramine (formed with gaseous chlorine). | |
| CAOF = Chloramine (formed with offsite hypochlorite). | |
| CAON = Chloramine (formed with onsite hypochlorite). | |
| CLDB = Chlorine dioxide. | |
| OZON = Ozone. | |
| ULVL = Ultraviolet light. | |
| OTHD = All other types of disinfectant/oxidant. | |
| NODU = No disinfectant/oxidant used. | |
| 11. Treatment Information | Treatment information associated with the sample point. Please select all that apply. |
| CON = Conventional (non-softening, consisting of at least coagulation/sedimentation basins and filtration). | |
| SFN = Softening. | |
| RBF = River bank filtration. | |
| PSD = Pre-sedimentation. | |
| INF = In-line filtration. | |
| DFL = Direct filtration. | |
| SSF = Slow sand filtration. | |
| BIO = Biological filtration (operated with an intention of maintaining biological activity within filter). | |
| UTR = Unfiltered treatment for surface water source. | |
| GWD = Groundwater system with disinfection only. | |
| PAC = Application of powder activated carbon. | |
| GAC = Granular activated carbon adsorption (not part of filters in CON, SFN, INF, DFL, or SSF). | |
| AIR = Air stripping (packed towers, diffused gas contactors). | |
| POB = Pre-oxidation with chlorine (applied before coagulation for CON or SFN plants or before filtration for other filtration plants). | |
| MFL = Membrane filtration. | |
| IEX = Ionic exchange. | |
| DAF = Dissolved air floatation. | |
| CWL = Clear well/finished water storage without aeration. | |
| CWA = Clear well/finished water storage with aeration. | |
| ADS = Aeration in distribution system (localized treatment). | |
| OTH = All other types of treatment. | |
| NTU = No treatment used. | |
| DKN = Do not know. | |
| 12. Sample Collection Date | The date the sample is collected, reported as 4-digit year, 2-digit month, and 2-digit day (YYYYMMDD). |
| 13. Sample Identification Code | An alphanumeric value up to 30 characters assigned by the laboratory to uniquely identify containers, or groups of containers, containing water samples collected at the same sampling location for the same sampling date. |
| 14. Contaminant | The unregulated contaminant for which the sample is being analyzed. |
| 15. Analytical Method Code | The identification code of the analytical method used. |
| 16. Extraction Batch Identification Code | Laboratory assigned extraction batch ID. Must be unique for each extraction batch within the laboratory for each method. For CCC samples report the Analysis Batch Identification Code as the value for this field. For methods without an extraction batch, leave this field null. |
| 17. Extraction Date | Date for the start of the extraction batch (YYYYMMDD). For methods without an extraction batch, leave this field null. |
| 18. Analysis Batch Identification Code | Laboratory assigned analysis batch ID. Must be unique for each analysis batch within the laboratory for each method. |
| 19. Analysis Date | Date for the start of the analysis batch (YYYYMMDD). |
| 20. Sample Analysis Type | The type of sample collected and/or prepared, as well as the fortification level. Permitted values include: CCCL = MRL level continuing calibration check; a calibration standard containing the contaminant, the internal standard, and surrogate analyzed to verify the existing calibration for those contaminants. |
| CCCM = Medium level continuing calibration check; a calibration standard containing the contaminant, the internal standard, and surrogate analyzed to verify the existing calibration for those contaminants. | |
| CCCH = High level continuing calibration check; a calibration standard containing the contaminant, the internal standard, and surrogate analyzed to verify the existing calibration for those contaminants. | |
| FS = Field sample; sample collected and submitted for analysis under this final rule. | |
| LFB = Laboratory fortified blank; an aliquot of reagent water fortified with known quantities of the contaminants and all preservation compounds. | |
| LRB = Laboratory reagent blank; an aliquot of reagent water treated exactly as a field sample, including the addition of preservatives, internal standards, and surrogates to determine if interferences are present in the laboratory, reagents, or other equipment. | |
| LFSM = Laboratory fortified sample matrix; a UCMR field sample with a known amount of the contaminant of interest and all preservation compounds added. | |
| LFSMD = Laboratory fortified sample matrix duplicate; duplicate of the laboratory fortified sample matrix. | |
| QCS = Quality control sample; a sample prepared with a source external to the one used for initial calibration and CCC. The QCS is used to check calibration standard integrity. | |
| FRB = Field reagent blank; an aliquot of reagent water treated as a sample including exposure to sampling conditions to determine if interferences or contamination are present from sample collection through analysis. | |
| 21. Analytical Result—Sign | A value indicating whether the sample analysis result was: (<) "less than" means the contaminant was not detected, or was detected at a level below the Minimum Reporting Level. (=) “equal to” means the contaminant was detected at the level reported in “Analytical Result— Measured Value.” |
| 22. Analytical Result—Measured Value | The actual numeric value of the analytical results for: Field samples; laboratory fortified matrix samples; laboratory fortified sample matrix duplicates; and concentration fortified. |
| 23. Additional Value | Represents the true value or the fortified concentration for spiked samples for QC Sample Analysis Types (CCCL, CCCM, CCCH, QCS, LFB, LFSM, and LFSMD). |
| 24. Laboratory Identification Code | The code, assigned by EPA, used to identify each laboratory. The code begins with the standard two-character State postal abbreviation; the remaining five numbers are unique to each laboratory in the State. |
| 25. Sample Event Code | A code assigned by the PWS for each sample event. This will associate samples with the PWS monitoring plan to allow EPA to track compliance and completeness. Systems must assign the following codes: |
| SE1, SE2, SE3, and SE4—Represent samples collected to meet UCMR Assessment Monitoring requirements; where “SE1” and “SE2” represent the first and second sampling period for all water types; and “SE3” and “SE4” represent the third and fourth sampling period for SW, GU, and MX sources only. | |
| 26. Historical Information for Contaminant Detections and Treatment | A yes or no answer provided by the PWS for each entry point to the distribution system. Question: Have you tested for the contaminant in your drinking water in the past? YES = If yes, did you modify your treatment and if so, what types of treatment did you implement? Select all that apply. |
| PAC = Application of powder activated carbon. | |
| GAC = Granular activated carbon adsorption (not part of filters in CON, SFN, INF, DFL, or SSF). | |
| IEX = Ionic exchange. | |
| NRO = Nanofiltration and reverse osmosis. | |
| OZN = Ozone. | |
| BAC = Biologically active carbon. | |
| MFL = Membrane filtration. | |
| UVL = Ultraviolet light. | |
| OTH = Other. | |
| NMT = Not modified after testing. | |
| NO = Have never tested for the contaminant. | |
| DK = Do not know. | |
| 27. Potential PFAS Sources | A yes or no answer provided by the PWS for each entry point to the distribution system. Question: Are you aware of any potential current and/or historical sources of PFAS that may have impacted the drinking water sources at your water system? |
| YES = If yes, select all that apply: | |
| MB = Military base. | |
| FT = Firefighting training school. | |
| AO = Airport operations. | |
| CW = Car wash or industrial launderers. | |
| PS = Public safety activities ( | |
| WM = Waste management. | |
| HW = Hazardous waste collection, treatment, and disposal. | |
| UW = Underground injection well. | |
| SC = Solid waste collection, combustors, incinerators. | |
| MF = Manufacturing. | |
| FP = Food packaging. | |
| TA = Textile and apparel ( | |
| PP = Paper. | |
| CC = Chemical. | |
| PR = Plastics and rubber products. | |
| MM = Machinery. | |
| CE = Computer and electronic products. | |
| FM = Fabricated metal products (e.g., nonstick cookware). | |
| PC = Petroleum and coal products. | |
| FF = Furniture. | |
| OG = Oil and gas production. | |
| UT = Utilities (e.g | |
| CT = Construction (e.g | |
| OT = Other. | |
| NO = Not aware of any potential current and/or historical sources. | |
| DK = Do not know. |