141.35 and 141.40 (a)(1)(i)(A)

EPA Draft- Do Not Cite or Quote

Proposed Revisions to CFR 

Parts 141.35 and 141.40

This document was prepared by EPA staff to aid the 

public's understanding of today's proposed revisions to the 

Unregulated Contaminant Monitoring Rule (UCMR 4). This 

document and all supporting documents for the UCMR 4 

proposed rule can be found at: http://www.regulations.gov/

docket ID EPA-HQ-OW-2015-0218. Note however, that the 

official proposed rule subject to public comment is the one 

that appears in the Federal Register (see 

https://www.federalregister.gov/). To the extent there are 

unintended differences between this document and the 

language in the Federal Register, the proposed Federal 

Register language is correct. These proposed revisions are 

revising the current UCMR 3 language. The official UCMR 3 

language can be found on the electronic Code of Federal 

Regulations at: www.ecfr.gov Title 40 Part 141.

Blue Underlined Text = Language Added

Red Strikethrough Text = Language Removed

EPA 815-B-15-006

November 2015
141.35 and 141.40 (a)(1)(i)(A)

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Unregulated Contaminant Monitoring Rule

Title 40: Protection of Environment

Parts 141.35 and 141.40

Revised as of July 1, 2012

§ 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); wholesale or 

consecutive populations are not included. 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: 

http://www2.epa.gov/dwucmrhttp://water.epa.gov/lawsregs/rulesregs/sdwa/ucmr/ucmr3/reporting.cf

m. 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 
141.35 and 141.40 (a)(1)(i)(A)

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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 October 1, 

2012December 31, 2017, 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 and inventory information. You must provide your sampling location(s) and

associate each source water location with its entry point location(s) inventory information by October 1, 

2012December 31, 2017, using EPA’s electronic data reporting system. You must submit, verify or 

update the following information for each sampling location, or for each approved representative 

sampling location (as specified in paragraph (c)(3) of this section regarding representative sampling 

locations): PWS identification (PWSID) Code; PWS Name; PWS Facility Identification Code; PWS Facility 

Nname; PWS Facility Type; Water Source Type; Sampling Point Identification Code; Sampling Point 

Name; and Sampling Point Type Code; (as defined in Table 1 of paragraph (e) 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 PWS’ 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 alternate EPTDS sampling 

locations from a previous UCMR cycle, or as provided for under § 141.23(a)(1), § 141.24(f)(1), or §

141.24(h)(1), may submit a copy of documentation from their State or EPA that approves their 

alternative sampling plan for EPTDSs. PWSs that do not have an approved alternative EPTDS sampling 

plan may submit a proposal to sample at representative EPTDS(s) rather than at each individual EPTDS if: 

tThey use ground water as a source; all of their well sources have either the same treatment or no 
141.35 and 141.40 (a)(1)(i)(A)

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treatment; and they have multiple EPTDSs from the same source, such as an aquifer. You must submit a 

copy of the existing alternate EPTDS sampling plan or your representative well proposal, as appropriate, 

[by August 1, 2012120 DAYS AFTER PUBLICATION OF THE FINAL RULE], as specified in paragraph (b)(1) 

of this section.

(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 select as representative 

of the ground water you supply from 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 producing 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 following information for each proposed representative 

sampling location: PWSID Code; PWS Name; PWS Facility Identification Code; PWS Facility Name; PWS 

Facility Type; and Sampling Point Identification Code and Sampling Point Name (as defined in Table 1, 

paragraph (e) of this section). 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 time of travel 

separating the representative well from 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. You must also provide a copy of this information to the State, unless 

otherwise directed by the State. Information about the actual or potential occurrence or nonoccurrence of contaminants in an individual well, or a well’s vulnerability to contamination, must not be 

used as a basis for selecting a representative well. 

(iii) Approval. EPA or the State (as specified in the Partnership Agreement reached between the 

State and EPA) will review your proposal, coordinate any necessary changes with you, and approve the 

final list of EPTDSs where you will be required to monitor. Your plan will not be final until you receive 

written approval from EPA or the State. 

(4) Contacting EPA if your PWS has not been notified of requirements. If you believe you are 

subject to UCMR requirements, as defined in § 141.40(a)(1) and (2)(i), and you have not been notified by 

either EPA or your State [by WITHIN October 1, 2012120 DAYS FROM PUBLICATION OF THE FINAL 

RULE], 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 
141.35 and 141.40 (a)(1)(i)(A)

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criteria specified in § 141.40(a)(2)(i), you are subject to the UCMR monitoring and reporting 

requirements, regardless of whether you have been notified by the State or EPA.

(5) Notifying EPA if your PWS cannot sample according to schedule—(i) General rescheduling 

notification requirements. Large systems may change their Assessment Mmonitoring (List 1) or PreScreening TestingSurvey (List 32)schedules up to October 1, 2012December 31, 2017, using EPA’s 

electronic data reporting system, as specified in paragraph (b)(1) of this section. After thesethis dates

hasve 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 October 1, 2012December 31, 2017, 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 each 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 6 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 ensure that your laboratory posts the data to EPA’s electronic 

data reporting system within 120 days from the sample collection date (sample collection must occur as 

specified in § 141.40(a)(4)). You have 60 days from when the laboratory posts the data in EPA’s 

electronic data reporting system to review, approve, and submit the data to the State and EPA, at the 

Web address specified in paragraph (b)(1) of this section. If you do not electronically approve and 

submit the laboratory data to EPA within 60 days of the laboratory’s posting data to EPA’s electronic 

reporting system, the data will be considered approved by you and available for State and EPA review. 
141.35 and 141.40 (a)(1)(i)(A)

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(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) Reporting sampling information. You must provide your sampling location(s) and associate

each source water location with its entry point location(s) by December 31, 2017, 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 PWS’ 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 6 9 by mailing or 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.with UCMR sample results. 
141.35 and 141.40 (a)(1)(i)(A)

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TABLE 1—UNREGULATED CONTAMINANT MONITORING REPORTING REQUIREMENTS

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 (e.g., Treatment Plant).

5. Public Water System Facility Type That code that identifies that type of facility as either: 

CC = consecutive connection

DS = distribution system

IN = source water intake

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 all or in part 

by a surface water source at any time during the twelve-month period). 

GW = ground water (to be reported for water facilities that are served entirely by a 

ground water source). 

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 twelve-month sampling period), 

and are not served at all by surface water during this 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., entry point 

to the distribution system, source water intake or distribution system sample at 

maximum residence time). The same identification code must be used to represent 

the sampling location for all current and future UCMR monitoring.

8. Sampling Point Name Unique sample point name, assigned once by the PWS, for every sample point ID (e.g., 

Entry Point).

9. Sampling Point Type Code A code that identifies the location of the sampling point as either: 

SR = source water taken from plant intake; untreated water entering the water 

treatment plant (i.e., a location prior to any treatment).

EP = entry point to the distribution system. 

MR = distribution system sample at maximum residence time.

10. Disinfectant Type All of the primary disinfectants/oxidants that have been added in the treatment plant 

to the water being sampled. To be reported by systems for each sampling point.

PEMB = Permanganate (applied before SR sample location)

PEMA = Permanganate (applied after SR sample location) 

HPXB = Hydrogen peroxide (applied before SR sample location)

HPXA = Hydrogen peroxide (applied after SR sample location)

CLGA = Gaseous chlorine

CLOF = Offsite Generated Hypochlorite (stored as a liquid form)
141.35 and 141.40 (a)(1)(i)(A)

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Data element Definition

CLON = Onsite Generated Hypochlorite

CAGC = Chloramine (formed from gaseous chlorine)

CAOF = Chloramine (formed from offsite hypochlorite)

CAON = Chloramine (formed from onsite hypochlorite)

CLDB = Chlorine dioxide (applied before SR sample location)

CLDA = Chlorine dioxide (applied after SR sample location)

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 water being sampled.

CON = Conventional (non-softening)

SCO = Softening conventional

RBF = River bank filtration

PSD = Pre-sedimentation

INF = In-line filtration

DFL = Direct filtration

PCF = Precoat filtration

SSF = Slow sand filtration

BIO = Biological filtration

REC = Reactor clarification (e.g. solids contact clarification, slurry recirculation 

clarification, Aciflo®) 

SBC = Sludge blanket clarification (e.g. Pulsator®, Super Pulsator®, contact 

adsorption clarifiers, floc-blanket clarifiers)

ADC = Adsorption clarification (contact adsorption clarification)

UTR = Unfiltered treatment

PAC = Application of powder activated carbon 

GAC = Granular activated carbon (not part of filters in CON, SCO, INF, DFL, or SSF)

AIR = Air stripping (packed towers, diffused gas contactors)

POB = Pre-oxidation/disinfection with chlorine (applied before SR sample location)

POA = Pre-oxidation/disinfection with chlorine (applied after SR sample location)

MFL = Membrane filtration

IEX = Ionic exchange

UVT = Ultraviolet light

AOX = Advanced oxidation (ultraviolet light with hydrogen peroxide and/or ozone)

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

12. Disinfectant Residual Type Secondary disinfectant type added in the distribution system for each finished water 

sample.

CL2 = Chlorine (i.e., originating from addition of free chlorine only)

CLM = Chloramines (originating from with addition of chlorine and ammonia or 

pre-formed chloramines) 

CAC = Chlorine and chloramines (if being mixed from chlorinated and 

chloraminated water)

NOD = No disinfectant residual

13. Sample Collection Date The date the sample is collected, reported as 4-digit year, 2-digit month, and 2-digit 

day (YYYY/MM/DD).

14. 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.
141.35 and 141.40 (a)(1)(i)(A)

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Data element Definition

15. Contaminant The unregulated contaminant for which the sample is being analyzed.

16. Analytical Method Code The identification code of the analytical method used.

17. 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.

18. Extraction Date Date for the start of the extraction batch (YYYY/MM/DD). For methods without an 

extraction batch, leave this field null.

19. Analysis Batch Identification Code Laboratory assigned analysis batch ID. Must be unique for each analysis batch within 

the laboratory for each method.

20. Analysis Date Date for the start of the analysis batch (YYYY/MM/DD).

21. Sample Analysis Type The type of sample collected and/or prepared, as well as the fortification level. 

Permitted values include: 

CF = concentration fortified; the concentration of a known contaminant added to a 

field sample reported with sample analysis types LFSM, LFSMD, LFB, CCC and QCS.

CCC = 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 rule. 

IS = internal standard; a standard that measures the relative response of 

contaminants.

LFB = lab fortified blank; an aliquot of reagent water fortified with known 

quantities of the contaminants and all preservation compounds.

LRB = lab 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.

QH = quality HAA; HAA sample collected and submitted for quality control 

purposes. 

SUR = surrogate standard; a standard that assesses method performance for each 

extraction.

22. Analytical Results—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.”

23. 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.

24. Additional Value Represents the true value or the fortified concentration for spiked samples for QC 

Sample Analysis Types (CCC, EQC, LFB, LFSM and LFSMD). For Sample Analysis Type FS 

and LRB and for IS and surrogate QC Contaminants, leave this field null. 

25. Laboratory Identification Code The code, assigned by EPA, used to identify each laboratory. The code begins with the 
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Data element Definition

standard two-character State postal abbreviation; the remaining five numbers are 

unique to each laboratory in the State.

26. 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: 

SEC1, SEC2, SEC3, SEC4, SEC5, SEC6, SEC7 and SEC8 - represent samples collected to 

meet UCMR Assessment Monitoring requirements for cyanotoxins; where “SEC1” 

represents the first sampling period, “SEC2” the second period and so forth, for all 

eight sampling events. 

SEA1, SEA2, SEA3 and SEA4 - represent samples collected to meet UCMR Assessment 

Monitoring requirements for the additional chemicals; where “SEA1” and “SEA2” 

represent the first and second sampling period for all water types; and “SEA3” and 

“SEA4” represent the third and fourth sampling period for SW and GU sources only.

[72 FR 389, Jan. 4, 2007, as amended at 77 FR 26096, May 2, 2012]

Subpart E—Special Regulations, Including Monitoring Regulations and 

Prohibition on Lead Use

§ 141.40 Monitoring requirements for unregulated contaminants. 

(a) General applicability. This section specifies the monitoring and quality control requirements 

that must be followed if you own or operate a public water system (PWS) that is subject to the 

Unregulated Contaminant Monitoring Regulation (UCMR), as specified in paragraphs (a)(1) and (2) of 

this section. In addition, this section specifies the UCMR requirements for State and Tribal participation. 

For the purposes of this section, PWS “population served,” “State,” “ PWS Official,” “PWS Technical 

Contact,” and “finished water” apply as defined in § 141.35(a). The determination of whether a PWS is 

required to monitor under this rule is based on the type of system (e.g., community water system, nontransient non-community water system, etc.), and its retail population, as indicated by SDWIS/Fed on 

December 31, 20150.

(1) Applicability to transient non-community systems. If you own or operate a transient noncommunity water system, you are not subject to monitoring requirements in this section. and you are 

notified by your State or EPA, you must permit the State, EPA or their contractors to collect samples for 

the contaminants specified on List 3 of Table 1, in paragraph (a)(3) of this section.

(2) Applicability to community water systems and non-transient non-community water 

systems—

(i) Large systems. If you own or operate a retail PWS (other than a transient non-community 

system) that serves more than 10,000 people, you must monitor according to the specifications in this 

paragraph (a)(2)(i). If you believe that your applicability status is different than EPA has specified in the 

notification letter that you received, or if you are subject to UCMR requirements and you have not been 

notified by either EPA or your State, you must report to EPA, as specified in § 141.35(b)(2) or (c)(4). 
141.35 and 141.40 (a)(1)(i)(A)

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(A) Assessment Monitoring. You must monitor for the unregulated contaminants on List 1 and 

Total Chromium per Table 1, UCMR Contaminant List, in paragraph (a)(3) of this section. If you serve a 

retail populationpopulation of more than 10,000 people, you are required to perform this monitoring 

regardless of whether you have been notified by the State or EPA. 

(B) Screening Survey. You must monitor for the unregulated contaminants on List 2 (Screening 

Survey) of Table 1, as specified in paragraph (a)(3) of this section, if your system serves 10,001 to 

100,000 people and you are notified by EPA or your State that you are part of the State Monitoring Plan 

for Screening Survey testing. If your system serves more than 100,000 people, you are required to 

conduct this Screening Survey testing regardless of whether you have been notified by the State or EPA. 

(C) Pre-Screen Testing. You must monitor for the unregulated contaminants on List 3 of Table 1, 

in paragraph (a)(3) of this section, if notified by your State or EPA that you are part of the Pre-Screen 

Testing. 

(ii) Small systems. Small PWSs, as defined in this paragraph, will not be selected to monitor for 

any more than one of the three monitoring lists provided in Table 1, UCMR Contaminant List, in 

paragraph (a)(3) of this section. EPA will provide sample containers, provide pre-paid air bills for 

shipping the sampling materials, conduct the laboratory analysis, and report and review monitoring 

results for all small systems selected to conduct monitoring under paragraphs (a)(2)(ii)(A) through (C) of 

this section. If you own or operate a PWS that serves 10,000 or fewer people you must monitor as 

follows: 

(A) Assessment Monitoring. You must monitor for the unregulated contaminants on List 1:

Assessment Monitoring Cyanotoxin Chemical Contaminants, or List 1: Assessment Monitoring Additional 

Chemical Contaminants and Total Chromium per Table 1, in paragraph (a)(3) of this section, if you are 

notified by your State or EPA that you are part of the State Monitoring Plan for Assessment Monitoring. 

(B) Screening Survey. You must monitor for the unregulated contaminants on List 2 of Table 1, in 

paragraph (a)(3) of this section, if notified by your State or EPA that you are part of the State Monitoring 

Plan for the Screening Survey. 

(C) Pre-Screen Testing. You must allow EPA or its representative to collect samples to support 

monitoring for the unregulated contaminants on List 3 of Table 1, in paragraph (a)(3) of this section, if 

you are notified by your State or EPA that you are part of the State Monitoring plan Plan for Pre-Screen 

Testing. In addition, you must permit the collection of samples as necessary for EPA to perform analysis 

for total coliforms, E. coli, bacteriophage, Enterococci and aerobic spores. 

(3) Analytes to be monitored. Lists 1, 2, and 3 of unregulated contaminants and total chromium 

monitoring are provided in the following table:
141.35 and 141.40 (a)(1)(i)(A)

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TABLE 1—UCMR CONTAMINANT LIST

1-Contaminant 2-CAS

Registry 

Number

3-Analytical

Methods a

4-Minimum

Reporting

Level b

5-Sampling

Location c

6-Period During 

Which

Monitoring to 

be Completed

List 1: Assessment Monitoring Cyanotoxin Chemical Contaminants

total microcystin N/A ELISA 0.3 μg/L EPTDS and 

SR

3/1/2018–

11/30/2020

anatoxin-a 64285-06-9 EPA 545 0.03 μg/L EPTDS 3/1/2018–

11/30/2020

cylindrospermopsin 143545-90-8 EPA 545 0.09 μg/L EPTDS 3/1/2018–

11/30/2020

microcystin-LA 96180-79-9 EPA 544 0.008 μg/L EPTDS 3/1/2018–

11/30/2020

microcystin-LF 154037-70-4 EPA 544 0.006 μg/L EPTDS 3/1/2018–

11/30/2020

microcystin-LR 101043-37-2 EPA 544 0.02 μg/L EPTDS 3/1/2018–

11/30/2020

microcystin-LY 123304-10-9 EPA 544 0.009 μg/L EPTDS 3/1/2018–

11/30/2020

microcystin-RR 111755-37-4 EPA 544 0.006 μg/L EPTDS 3/1/2018–

11/30/2020

microcystin-YR 101064-48-6 EPA 544 0.02 μg/L EPTDS 3/1/2018–

11/30/2020

nodularin 118399-22-7 EPA 544 0.005 μg/L EPTDS 3/1/2018–

11/30/2020

List 1: Assessment Monitoring Additional Chemical Contaminants

Metals

germanium 7440-56-4 EPA 200.8, 

ASTM D5673-

10, SM 3125

0.3 μg/L EPTDS 3/1/2018–

11/30/2020

manganese 7439-96-5 EPA 200.8,

ASTM D5673-

10, SM 3125

0.4 μg/L EPTDS 3/1/2018–

11/30/2020

Pesticides and a Pesticide Manufacturing Byproduct

alpha-hexachlorocyclohexane 319-84-6 EPA 525.3 0.01 μg/L EPTDS 3/1/2018–

11/30/2020

chlorpyrifos 2921-88-2 EPA 525.3 0.03 μg/L EPTDS 3/1/2018–

11/30/2020

dimethipin 55290-64-7 EPA 525.3 0.2 μg/L EPTDS 3/1/2018–

11/30/2020

ethoprop 13194-48-4 EPA 525.3 0.03 μg/L EPTDS 3/1/2018–

11/30/2020
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1-Contaminant 2-CAS

Registry 

Number

3-Analytical

Methods a

4-Minimum

Reporting

Level b

5-Sampling

Location c

6-Period During 

Which

Monitoring to 

be Completed

oxyfluorfen 42874-03-3 EPA 525.3 0.05 μg/L EPTDS 3/1/2018–

11/30/2020

profenofos 41198-08-7 EPA 525.3 0.3 μg/L EPTDS 3/1/2018–

11/30/2020

tebuconazole 107534-96-3 EPA 525.3 0.2 μg/L EPTDS 3/1/2018–

11/30/2020

total permethrin (cis- & trans-) 52645-53-1 EPA 525.3 0.04 μg/L EPTDS 3/1/2018–

11/30/2020

tribufos 78-48-8 EPA 525.3 0.07 μg/L EPTDS 3/1/2018–

11/30/2020

Brominated Haloacetic Acid (HAA) Groupsd

HAA5 N/A EPA 552.3 or 

EPA 557

N/A Stage 2 

DBPR and/or 

DSMRT

3/1/2018–

11/30/2020

HAA6Br N/A EPA 552.3 or 

EPA 557

N/A Stage 2 

DBPR and/or 

DSMRT

3/1/2018–

11/30/2020

HAA9 N/A EPA 552.3 or 

EPA 557

N/A Stage 2 

DBPR and/or 

DSMRT

3/1/2018–

11/30/2020

Alcohols

1-butanol 71-36-3 EPA 541 2.0 μg/L EPTDS 3/1/2018–

11/30/2020

2-methoxyethanol 109-86-4 EPA 541 0.4 μg/L EPTDS 3/1/2018–

11/30/2020

2-propen-1-ol 107-18-6 EPA 541 0.5 μg/L EPTDS 3/1/2018–

11/30/2020

Other Semivolatile Chemicals

butylated hydroxanisole 25013-16-5 EPA 530 0.03 μg/L EPTDS 3/1/2018–

11/30/2020

o-toluidine 95-53-4 EPA 530 0.007 μg/L EPTDS 3/1/2018–

11/30/2020

quinoline 91-22-5 EPA 530 0.02 μg/L EPTDS 3/1/2018–

11/30/2020

List 2: Screening Survey

Reserved Reserved Reserved Reserved Reserved Reserved

List 3: Pre-Screen Testing

Reserved Reserved Reserved Reserved Reserved Reserved

Column headings are: 
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1—Contaminant: The name of the contaminant to be analyzed. 

2—CAS (Chemical Abstract Service) Registry Number or Identification Number: A unique number identifying the chemical 

contaminants. 

3—Analytical Methods: Method numbers identifying the methods that must be used to test the contaminants. 

4—Minimum Reporting Level (MRL): The value and unit of measure at or above which the concentration of the 

contaminant must be measured using the approved analytical methods. If EPA determines, after the first six months of 

monitoring that the specified MRLs result in excessive resampling, EPA will establish alternate MRLs and will notify affected 

PWSs and laboratories of the new MRLs. N/A is defined as non-applicable. 

5—Sampling Location: The locations within a PWS at which samples must be collected. 

6—Period During Which Monitoring to be Completed: The time period during which the sampling and testing will occur for 

the indicated contaminant. 

a The analytical procedures shall be performed in accordance with the documents associated with each method, see 

paragraph (c) of this section. 

b The MRL is the minimum concentration of each analyte that must be reported to EPA. 

c Sampling must occur at entry points to the distribution system (EPTDSs) after treatment is applied that represent each 

non-emergency water source in routine use over the 12-month period of monitoring. Systems that purchase water with 

multiple connections from the same wholesaler may select one representative connection from that wholesaler. This EPTDS 

sampling location must be representative of the highest annual volume connections. If the connection selected as the 

representative EPTDS is not available for sampling, an alternate highest volume representative connection must be sampled. 

See 40 CFR 141.35(c)(3) for an explanation of the requirements related to the use of representative ground water EPTDSs. 

Sampling for brominated HAA groups must be conducted at the Stage 2 Disinfectants and Disinfection Byproduct Rule (DBPR) 

sampling locations (40 CFR 141.622). If these locations are not defined, the PWS is required to collect samples at locations 

that best represent the distribution system maximum residence time (DSMRT). DSMRT is defined as an active point (i.e., a 

location that currently provides water to customers) in the distribution system where the water has been in the system the 

longest relative to the EPTDS. Sampling must occur at source water (SR) intake locations defined by EPA under the UCMR as 

untreated water entering the water treatment plant (i.e., a location prior to any treatment). Systems subject to the Long 

Term 2 Enhanced Surface Water Treatment Rule (LT2) would use their source water sampling site(s) from 40 CFR 141.703. 

Systems subject to the Stage 1 DBPR would use their TOC source water sampling site(s) from 40 CFR 141.132. TOC source 

water sampling site(s) were set under Stage 1 DBPR and remain unchanged under Stage 2 DBPR. If a system has two different 

sampling locations for LT2 and Stage 1 DBPR, the system would select the sample point the best represents the definition of 

source water sample location(s) for UCMR. For each EPTDS there should be one source water sample point associated with 

that EPTDS. It is possible that different EPTDSs share the same source water. PWSs that purchase 100 percent of their water; 

“consecutive systems” are not required to collect source water samples. dTOC and bromide must be collected at the same time as HAA samples. These indicator samples must be collected at a 

single source water intake (as defined in footnote c, above) using methods already approved for compliance monitoring. TOC 

methods include: SM 5310 B, SM 5310 C, SM 5310 D (21st edition), or SM 5310 B-00, SM 5310 C-00, SM 5310 D-00 (SM 

Online), EPA Method 415.3 (Rev. 1.1 or 1.2). Bromide methods include: EPA Methods 300.0 (Rev. 2.1), 300.1 (Rev. 1.0), 317.0 

(Rev. 2.0), 326.0 (Rev. 1.0) or ASTM D 6581-12. The MRLs for the individual HAAs are discussed in paragraph (a)(5)(v) of this 

section. e Temperature and pH must be measured at the same time as cyanotoxin samples at the source water intake as described 

in footnote c, above. pH methods include: EPA Method 150.1 and 150.2, ASTM D1293-12, SM 4500-H+ B (21st edition) or SM 

4500-H+ B-00 (SM Online). Temperature methods include: SM 2550 (21st edition), or SM 2550-00 (SM Online). 

(4) Sampling requirements—(i) Large systems. If you serve more than 10,000 people and meet 

the UCMR applicability criteria specified in paragraph (a)(2)(i) of this section, you must comply with the 

requirements specified in paragraphs (a)(4)(i)(A) through (I) of this section. Your samples must be 

collected according to the schedule that you are assigned by EPA or your State, or the schedule that you 

revised using EPA’s electronic data reporting system on or before October December 31, 20172. Your 

schedule must follow both the timing and frequency of monitoring specified in Tables 1 and 2 of this 

section. 
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(A) Monitoring period. You must collect the samples in one continuous 12-month period for List 

1 Assessment Monitoring and, if applicable, for List 2 Screening Survey, or List 3 Pre-Screen Testing, 

during the time frame indicated in column 6 of Table 1, in paragraph (a)(3) of this section. EPA or your 

State will specify the month(s) and year(s) in which your monitoring must occur. As specified in §

141.35(c)(5), you must contact EPA if you believe you cannot conduct monitoring according to your 

schedule. 

(B) Frequency. You must collect the samples within the time frame and according to the 

frequency specified by contaminant type and water source type for each sampling location, as specified 

in Table 2, in this paragraph. For the second or subsequent round of sampling, if a sample location is 

non-operational for more than one month before and one month after the scheduled sampling month 

(i.e., it is not possible for you to sample within the window specified in Table 2, in this paragraph), you 

must notify EPA as specified in § 141.35(c)(5) to reschedule your sampling. 

TABLE 2—MONITORING FREQUENCY BY CONTAMINANT AND WATER SOURCE TYPES

Contaminant 

type

Water source type Time frame1 Frequency2

List 1 

Cyanotoxins 

Chemicals

Surface water or Ground water 

under the direct influence of surface 

water (GWUDI)

March –

November

You must monitor twice a month for 

four consecutive months (total of eight 

sampling events). Sample events must 

occur two weeks apart. 

List 1 

Contaminants –

Additional 

Chemicals 

Surface water or GWUDI March –

November 

You must monitor four times during 

your 12-month monitoring period. 

Sample events must occur two months 

apart. (Example: If your first sampling 

event is in March, the second 

monitoring must occur during May, the 

third during July, and the fourth during 

September). 

Ground water March –

November

You must monitor two times during 

your 12-month monitoring period. 

Sample events must occur six months 

apart. (Example: If your first monitoring 

is in March, the second monitoring 

must occur during September. If your 

first monitoring is in November, the 

second monitoring must occur in May).

1 No sampling will take place during the months of December, January or February, except for resampling purposes. 

2 Systems must assign a sample event code for each contaminant listed in Table 1. Sample event codes must be assigned 

by the PWS for each sample event. For more information on sample event codes see § 141.35(e) Table 1. 

(C) Location. You must collect samples for each List 1 Assessment Monitoring contaminant, and, 

if applicable, for each List 2 Screening Survey, or List 3 Pre-Screen Testing contaminant, as specified in 

Table 1, in paragraph (a)(3) of this section. Samples must be collected at each sample point that is 
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specified in column 5 and footnote c of Table 1, in paragraph (a)(3) of this section. PWSs conducting List 

1 monitoring for the brominated HAA groups must collect TOC and bromide samples as specified in 

footnote d of Table 1, in paragraph (a)(3) of this section. PWSs conducting List 1 monitoring for 

cyanotoxins must measure temperature and pH as specified in footnote e of Table 1, in paragraph (a)(3) 

of this section. If you are a ground water system with multiple EPTDSs, and you request and receive 

approval from EPA or the State for sampling at representative EPTDS(s), as specified in § 141.35(c)(3), 

you must collect your samples from the approved representative sampling location(s). Systems 

conducting Assessment Monitoring must also sample for total chromium, chromium-6, cobalt, 

molybdenum, strontium, vanadium, and chlorate at the location that represents the maximum 

residence time in the distribution system (DSMRT). DSMRT is defined as an active point (i.e, a location 

that currently provides water to customers) in the distribution system where the water has been in the 

system the longest relative to the EPTDS. 

(D) Sampling instructions. For each List 1 Assessment Monitoring contaminant, and, if 

applicable, for each List 2 Screening Survey, or List 3 Pre-Screen Testing contaminant, you must follow 

the sampling procedure for the method specified in column 3 of Table 1, in paragraph (a)(3) of this 

section. In addition, you must not composite (that is, combine, mix, or blend) the samples; you must 

collect and preserve each sample separately. 

(E) Sample collection and shipping time. If you must ship the samples for analysis, you must 

collect the samples early enough in the day to allow adequate time to send the samples for overnight 

delivery to the laboratory. You should not collect samples on Friday, Saturday, or Sunday because 

sampling on these days may not allow samples to be shipped and received at the laboratory at the 

required temperature, unless you have made special arrangements with your laboratory to receive the 

samples. 

(F) Analytical methods. For each contaminant, you must use the respective analytical methods 

for List 1, and, if applicable, for List 2, or List 3 that are specified in column 3 of Table 1, in paragraph 

(a)(3) of this section; report values at or above the minimum reporting levels for List 1, and, if applicable, 

for List 2 Screening Survey, or List 3 Pre-Screen Testing, that are specified in column 4 of Table 1, in 

paragraph (a)(3) of this section; and conduct the quality control procedures specified in paragraph (a)(5) 

of this section. 

(G) Laboratory errors or sampling deviations. If the laboratory data do not meet the required QC 

criteria, as specified in paragraph (a)(5) of this section, or you do not follow the required sampling 

procedures, as specified in paragraphs (a)(4) of this section, you must resample within 30 days of being 

informed or becoming aware of these facts. This resampling is not for the purpose of confirming 

previous results, but to correct the sampling or laboratory error. All systems must report the results 

obtained from the first sampling for each sampling period, except for cases of sampling or laboratory 

errors. For the purposes of this rule, no samples are to be recollected for the purposes of confirming the 

results observed in a previous sampling. 
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(H) Analysis. For the List 1 contaminants, and, if applicable, List 2 Screening Survey, or List 3 PreScreen Testing contaminants, identified in Table 1, paragraph (a)(3) of this section, you must arrange for 

testing by a laboratory that has been approved by EPA according to requirements in paragraph (a)(5)(ii) 

of this section. 

(I) Review and reporting of results. After you have received the laboratory results, you must 

review, approve, and submit the system information, and sample collection data and test results. You 

must report the results as provided in § 141.35(c)(6). 

(ii) Small systems. If you serve 10,000 or fewer people and are notified that you are part of the 

State Monitoring Plan for Assessment Monitoring, Screening Survey or Pre-Screen monitoring, you must 

comply with the requirements specified in paragraphs (a)(4)(ii)(A) through (H) of this section. If EPA or 

the State informs you that they will be collecting your UCMR samples, you must assist them in 

identifying the appropriate sampling locations and in collecting the samples. 

(A) Monitoring period and frequency. You must collect samples at the times specified for you by 

the State or EPA. Your schedule must follow both the timing of monitoring specified in Table 1, List 1, 

and, if applicable, List 2, or List 3, and the frequency of monitoring in Table 2 of this section. 

(B) Location. You must collect samples at the locations specified for you by the State or EPA. 

(C) Sample kits. You must store and maintain the sample collection kits sent to you by the UCMR 

Sampling Coordinator in accordance with the kit’s instructions. The sample kit will include all necessary 

containers, packing materials and cold packs, instructions for collecting the sample and sample 

treatment (such as dechlorination or preservation), report forms for each sample, contact name and 

telephone number for the laboratory, and a prepaid return shipping docket and return address label. If 

any of the materials listed in the kit’s instructions are not included in the kit or arrive damaged, you 

must notify the UCMR Sampling Coordinator who sent you the sample collection kits. 

(D) Sampling instructions. You must comply with the instructions sent to you by the State or EPA 

concerning the use of containers, collection (how to fill the sample bottle), dechlorination and/or 

preservation, and sealing and preparation of sample and shipping containers for shipment. You must not 

composite (that is, combine, mix, or blend) the samples. You also must collect, preserve, and test each 

sample separately. You must also comply with the instructions sent to you by the UCMR Sampling 

Coordinator concerning the handling of sample containers for specific contaminants. 

(E) Sampling deviations. If you do not collect a sample according to the instructions provided to 

you for a listed contaminant, you must report the deviation within 7 days of the scheduled monitoring 

on the sample reporting form, as specified in § 141.35(d)(2). You must resample following instructions 

that you will be sent from the UCMR Sampling Coordinator or State. A copy of the form must be sent to 

the laboratory with the recollected samples, and to the UCMR Sampling Coordinator. 

(F) Reserved. Duplicate samples. EPA will select a subset of systems in the State Monitoring Plan 

that must collect duplicate samples for quality control. If your system is selected, you will receive two 
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sample kits for an individual sampling location that you must use. You must use the same sampling 

protocols for both sets of samples, following the instructions in the duplicate sample kit. 

(G) Sampling forms. You must completely fill out each of the sampling forms and bottles sent to 

you by the UCMR Sampling Coordinator, including data elements listed in § 141.35(e) for each sample, 

as specified in § 141.35(d)(2). You must sign and date the sampling forms. 

(H) Sample collection and shipping. You must collect the samples early enough in the day to 

allow adequate time to send the samples for overnight delivery to the laboratory. You should not collect 

samples on Friday, Saturday, or Sunday because sampling on these days may not allow samples to be 

shipped and received at the laboratory at the required temperature unless you have made special 

arrangements with EPA for the laboratory to receive the samples. Once you have collected the samples 

and completely filled in the sampling forms, you must send the samples and the sampling forms to the 

laboratory designated on the air bill. 

(iii) Phased sample analysis for microcystins. You must collect the three required samples (one 

at the source water intake and two at the EPTDS) for each sampling event, but not all samples may need 

to be analyzed. PWSs that purchase 100 percent of their water; “consecutive systems” only sample at 

their EPTDS. If the ELISA result from the source water intake is less than 0.3 μg/L, report that result and 

do not analyze the additional EPTDS samples for that sample event. If the ELISA result from the source 

water intake is greater than or equal to 0.3 μg/L, report that value and analyze the EPTDS ELISA sample.

If the EPTDS ELISA result is less than 0.3 μg/L, report that result and do not analyze the additional EPTDS 

samples for that sample event. If the EPTDS ELISA result is greater than or equal to 0.3 μg/L, report the 

value and analyze the other microcystin samples collected at the EPTDS using EPA Method 544.

(5) Quality control requirements. If your system serves more than 10,000 people, you must 

ensure that the quality control requirements listed below are met during your sampling procedures and 

by the laboratory conducting your analyses. You must also ensure that all method quality control 

procedures and all UCMR quality control procedures are followed. 

(i) Sample collection/preservation. You must follow the sample collection and preservation 

requirements for the specified method for each of the contaminants in Table 1, in paragraph (a)(3) of 

this section. These requirements specify sample containers, collection, dechlorination, preservation, 

storage, sample holding time, and extract storage and/or holding time that you must assure that the 

laboratory follow. 

(ii) Laboratory approval for Lists 1, List 2 and List 3. To be approved to conduct UCMR testing, 

the laboratory must be certified under § 141.28 for one or more compliance analyses; demonstrate for 

each analytical method it plans to use for UCMR testing that it can meet the Initial Demonstration of 

Capability (IDC) requirements detailed in the analytical methods specified in column 3 of Table 1, in 

paragraph (a)(3) of this section; and successfully participate in the UCMR Proficiency Testing (PT) 

Program administered by EPA for each analytical method it plans to use for UCMR testing. UCMR 

laboratory approval decisions will be granted on an individual method basis for the methods listed in 
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column 3 of Table 1 in paragraph (a)(3) of this section for List 1, List 2, and List 3 contaminants. 

Laboratory approval is contingent upon the capability of the laboratory to post monitoring data to the 

EPA electronic data reporting system. To participate in the UCMR Laboratory Approval Program, the 

laboratory must complete and submit the necessary registration forms [DATE 60 DAYS AFTER 

PUBLICATION OF THE FINAL RULE], and necessary application material [DATE 120 DAYS AFTER 

PUBLICATION OF THE FINAL RULE] by August 1, 2012. Correspondence must be addressed to: UCMR 

Laboratory Approval Coordinator, USEPA, Technical Support Center, 26 West Martin Luther King Drive, 

(MS 140), Cincinnati, OH 45268; or emailed to EPA at: UCMR_Sampling_Coordinator@epa.gov. 

(iii) Minimum Reporting Level. The MRL is an estimate of the quantitation limit. Assuming good 

instrumentation and experienced analysts, an MRL is achievable, with 95% confidence, by 75% of 

laboratories nationwide. 

(A) Validation of laboratory performance. Your laboratory must be capable of quantifying each 

contaminant listed in Table 1, at or below the MRL specified in column 4 of Table 1, in paragraph (a)(3) 

of this section. You must ensure that the laboratory completes and has on file and available for your 

inspection, records of two distinct procedures. First, your laboratory must have conducted an IDC 

involving replicate analyses at or below the MRL as described in this paragraph. Second, for each day 

that UCMR analyses are conducted by your laboratory, a validation of its ability to quantify each 

contaminant, at or below the MRL specified in column 4 of Table 1, in paragraph (a)(3) of this section, 

following the procedure listed in paragraph (a)(5)(iii)(B) of this section, must be performed. The 

procedure for initial validation of laboratory performance at or below the MRL is as follows: 

(1) All laboratories performing analysis under UCMR must demonstrate that they are capable of 

meeting data quality objectives at or below the MRL listed in Table 1, column 4, in paragraph (a)(3) of 

this section. 

(2) The MRL, or any concentration below the MRL, at which performance is being evaluated, 

must be contained within the range of calibration. The calibration curve regression model and the range 

of calibration levels that are used in these performance validation steps must be used in all routine 

sample analyses used to comply with this regulation. Only straight line or quadratic regression models 

are allowed. The use of either weighted or unweighted models is permitted. The use of cubic regression 

models is not permitted. 

(3) Replicate analyses of at least seven (7) fortified samples in reagent water must be performed 

at or below the MRL for each analyte, and must be processed through the entire method procedure (i.e.,

including extraction, where applicable, and with all preservatives). 

(4) A prediction interval of results (PIR), which is based on the estimated arithmetic mean of 

analytical results and the estimated sample standard deviation of measurement results, must be 

determined by Equation 1:

Equation 1 PIR = Mean ± s × tt(df,1−∝/2) × �1 + 1

nn
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Where: 

t is the Student’s t value with df degrees of freedom and confidence level (1-α), 

s is the sample standard deviation of n replicate samples fortified at the MRL, 

n is the number of replicates. 

(5) The values needed to calculate the PIR using Equation 1 are: Number of replicates (n); 

Student’s t value with a two-sided 99% confidence level for n number of replicates; the average (mean) 

of at least seven replicates; and the sample standard deviation. Factor 1 is referred to as the Half Range 

PIR (HRPIR). 

HRPIR = ss × tt(dddd,1−∝/2) × �1 +

1

nn

For a certain number of replicates and for a certain confidence level in Student’s t, this factor 

C = tt(dddd,1−∝/2) × �1 +

1

nn

is constant, and can be tabulated according to replicate number and confidence level for the Student’s t. 

Table 3 in this paragraph lists the constant factor (C) for replicate sample numbers 7 through 10 with a 

confidence level of 99% for Student’s t. 

(6) The HRPIR is calculated by Equation 2: 

Equation 2 HRPIR = ss × C

(7) The PIR is calculated by Equation 3: 

Equation 3 PIR = Mean ± HRPIR

TABLE 3—THE CONSTANT FACTOR (C) TO BE MULTIPLIED BY THE STANDARD DEVIATION TO DETERMINE THE HALF 

RANGE INTERVAL OF THE PIR (STUDENT’S T 99% CONFIDENCE LEVEL) A

Replicates Degrees of freedom Constant factor (C) to be multiplied by the standard 

deviation

7 6 3.963

8 7 3.711

9 8 3.536

10 9 3.409

a The critical t-value for a two-sided 99% confidence interval is equivalent to the critical t-value for a one- sided 99.5% 

confidence interval, due to the symmetry of the t-distribution. PIR = Prediction Interval of Results. 
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(8) The lower and upper result limits of the PIR must be converted to percent recovery of the 

concentration being tested. To pass criteria at a certain level, the PIR lower recovery limits cannot be 

lower than the lower recovery limits of the QC interval (50%), and the PIR upper recovery limits cannot 

be greater than the upper recovery limits of the QC interval (150%). When either of the PIR recovery 

limits falls outside of either bound of the QC interval of recovery (higher than 150% or less than 50%), 

laboratory performance is not validated at the concentration evaluated. If the PIR limits are contained 

within both bounds of the QC interval, laboratory performance is validated for that analyte. 

(B) Quality control requirements for validation of laboratory performance at or below the MRL. 

(1) You must ensure that the calibration curve regression model and that the range of 

calibration levels that are used in these performance validation steps are used in future routine sample 

analysis. Only straight line or quadratic regression models are allowed. The use of either weighted or 

unweighted models is permitted. The use of cubic regression models is not permitted. 

(2) You must ensure, once your laboratory has performed an IDC as specified in each analytical 

method (demonstrating that DQOs are met at or below an MRL), that a daily performance check is 

performed for each analyte and method. A single laboratory blank, fortified at or below the MRL for 

each analyte, must be processed through the entire method procedure. The measured concentration for 

each analyte must be converted to a percent recovery, and if the recovery is within 50%-150% 

(inclusive), the daily performance of the laboratory has been validated. The results for any analyte for 

which 50%-150% recovery cannot be demonstrated during the daily check are not valid. Laboratories 

may elect to re-run the daily performance check sample if the performance for any analyte or analytes 

cannot be validated. If performance is validated for these analytes, the laboratory performance is 

considered validated. Alternatively, the laboratory may re-calibrate and repeat the performance 

validation process for all analytes. 

(iv) Laboratory fortified sample matrix and laboratory fortified sample matrix duplicate. You 

must ensure that your laboratory prepares and analyzes the Laboratory Fortified Sample Matrix (LFSM) 

sample for accuracy and Laboratory Fortified Sample Matrix Duplicate (LFSMD) samples for precision to 

determine method accuracy and precision for all contaminants in Table 1, in paragraph (a)(3) of this 

section. LFSM/LFSMD samples must be prepared using a sample collected and analyzed in accordance 

with UCMR requirements and analyzed at a frequency of 5% (or 1 LFSM/LFSMD set per every 20 

samples) or with each sample batch, whichever is more frequent. In addition, the LFSM/LFSMD 

fortification concentrations must be alternated between a low-level fortification and mid-level 

fortification approximately 50% of the time. (For example: A set of 40 samples will require preparation 

and analysis of 2 LFSM/LFSMD paired samples. The first LFSM/LFSMD paired sample set must be 

fortified at either the low-level or mid-level, and the second LFSM/LFSMD paired sample set must be 

fortified with the other standard, either the low- level or mid-level, whichever was not used for the 

initial LFSM/LFSMD paired sample set.) The low-level LFSM/LFSMD fortification concentration must be 

within ±50% of the MRL for each contaminant (e.g., for an MRL of 1 μg/L the acceptable fortification 

levels must be between 0.5 μg/L and 1.5 μg/L). The mid-level LFSM/ LFSMD fortification concentration 

must be within ±20% of the mid-level calibration standard for each contaminant, and is to represent, 
141.35 and 141.40 (a)(1)(i)(A)

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where possible and where the laboratory has data from previously analyzed samples, an approximate 

average concentration observed in previous analyses of that analyte. There are no UCMR contaminant 

recovery acceptance criteria specified for LFSM/LFSMD analyses. All LFSM/LFSMD data are to be 

reported. 

(v) Method defined quality control. You must ensure that your laboratory performs Laboratory 

Fortified Blanks and Laboratory Performance Checks, as appropriate to the method’s requirements, for 

those methods listed in Table 1, column 3, in paragraph (a)(3) of this section. Each method specifies 

acceptance criteria for these QC checks.

(A) The following HAA results must be reported using EPA’s electronic data reporting system for 

quality control purposes.

TABLE 4 – HAA QC RESULTS

1-Contaminant 2-CAS 

Registry 

Number

3-Analytical 

Methods a

4-Minimum 

Reporting 

Level b

5-HAA6Br 

Group

6-HAA9 

Group

7-HAA5 

Group 

Brominated Haloacetic Acid (HAA) Groups

Bromochloroacetic 

acid (BCAA)

5589-96-8 EPA 552.3 

or EPA 557

0.3 μg/L

Bromodichloroacetic 

acid (BDCAA)

71133-14-7 EPA 552.3 

or EPA 557

0.5 μg/L

Chlorodibromoacetic 

acid (CDBAA)

5278-95-5 EPA 552.3 

or EPA 557

0.3 μg/L

HAA6Br

Tribromoacetic acid 

(TBAA)

75-96-7 EPA 552.3 

or EPA 557

2.0 μg/L

Monobromoacetic 

acid (MBAA)

79-08-3 EPA 552.3 

or EPA 557

0.3 μg/L HAA9

Dibromoacetic acid 

(DBAA)

631-64-1 EPA 552.3 

or EPA 557

0.3 μg/L

Dichloroacetic acid 

(DCAA)

79-43-6 EPA 552.3 

or EPA 557

0.2 μg/L HAA5

Monochloroacetic 

acid (MCAA)

79-11-8 EPA 552.3 

or EPA 557

2.0 μg/L

Trichloroacetic acid 

(TCAA)

76-03-9 EPA 552.3 

or EPA 557

0.5 μg/L

Column headings are: 

1—Contaminant: The name of the contaminant to be analyzed. 

2—CAS (Chemical Abstract Service) Registry Number or Identification Number: A unique number identifying the chemical 

contaminants. 

3—Analytical Methods: Method numbers identifying the methods that must be used to test the contaminants. 

4—Minimum Reporting Level (MRL): The value and unit of measure at or above which the concentration of the 

contaminant must be measured using the approved analytical methods. If EPA determines, after the first six months of 

monitoring that the specified MRLs result in excessive resampling, EPA will establish alternate MRLs and will notify affected

PWSs and laboratories of the new MRLs.

5-7 – HAA groups identified in paragraph (a)(3) of this section to be monitored as UCMR contaminants. 

a The analytical procedures shall be performed in accordance with the documents associated with each method, see 

paragraph (c) of this section, and must meet all quality control requirements outlined paragraph (a)(5) of this section. b The MRL is the minimum concentration of each analyte that must be reported to EPA. 
141.35 and 141.40 (a)(1)(i)(A)

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(vi) Reporting. You must require your laboratory to submit these data electronically to the State 

and EPA using EPA’s electronic data reporting system, accessible at 

http://www2.epa.gov/dwucmrhttp://water.epa.gov/lawsregs/rulesregs/sdwa/ucmr/ucmr3/reporting.cf

m, within 120 days from the sample collection date. You then have 60 days from when the laboratory 

posts the data to review, approve and submit the data to the State and EPA, via EPA’s electronic data 

reporting system. If you do not electronically approve and submit the laboratory data to EPA within 60 

days of the laboratory posting data to EPA’s electronic reporting system, the data will be considered 

approved and available for State and EPA review. 

(6) Violation of this rule—(i) Monitoring violations. Any failure to monitor in accordance with §

141.40(a)(3)-(5) is a monitoring violation. 

(ii) Reporting violations. Any failure to report in accordance with § 141.35 is a reporting 

violation. 

(b) Petitions and waivers by States—(1) Governors’ petition for additional contaminants. The 

Safe Drinking Water Act allows Governors of seven (7) or more States to petition the EPA Administrator 

to add one or more contaminants to the UCMR Contaminant List in paragraph (a)(3) of this section. The 

petition must clearly identify the reason(s) for adding the contaminant(s) to the monitoring list, 

including the potential risk to public health, particularly any information that might be available 

regarding disproportional risks to the health and safety of children, the expected occurrence 

documented by any available data, any analytical methods known or proposed to be used to test for the 

contaminant(s), and any other information that could assist the Administrator in determining which 

contaminants present the greatest public health concern and should, therefore, be included on the 

UCMR Contaminant List in paragraph (a)(3) of this section. 

(2) State-wide waivers. A State can waive monitoring requirements only with EPA approval and 

under very limited conditions. Conditions and procedures for obtaining a waiver are as follows: 

(i) Application. A State may apply to EPA for a State-wide waiver from the unregulated 

contaminant monitoring requirements for PWSs serving more than 10,000 people. To apply for such a 

waiver, the State must submit an application to EPA that includes the following information: The list of 

contaminants on the UCMR Contaminant List for which a waiver is requested, along with documentation 

for each contaminant in the request demonstrating that the contaminants or their parent compounds 

do not occur naturally in the State, and certifying that during the past 15 years they have not been used, 

applied, stored, disposed of, released, or detected in the source waters or distribution systems in the 

State. 

(ii) Approval. EPA will review State applications and notify the State whether it accepts or rejects 

the request. The State must receive written approval from EPA before issuing a State-wide waiver. 

(c) Incorporation by reference. These standards are incorporated by reference into this section 

with the approval of the Director of the Federal Register under 5 U.S.C. 552(a) and 1 CFR part 51. All 

approved material is available for inspection either electronically at www.regulations.gov, in hard copy 
141.35 and 141.40 (a)(1)(i)(A)

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Page 23 of 26

at the Water Docket, EPA/DC, and from the sources below. The Public Reading Room (EPA West, Room 

3334, 1301 Constitution Ave. NW., Washington, DC) is open from 8:30 a.m. to 4:30 p.m., Monday 

through Friday, excluding legal holidays. The telephone number for this Public Reading Room is (202) 

566-1744, and the telephone number for the Water Docket is (202) 566-2426. The material is also 

available for inspection at the National Archives and Records Administration (NARA). For information on 

the availability of this material at NARA, call (202) 741-6030 or go to http://www.archives.gov/federalregister/cfr/about.html. 

(1) The following methods are from the U.S. Environmental Protection Agency, Water Docket, 

EPA/DC, EPA West, Room 3334, 1301 Constitution Ave. NW., Washington, DC 20004.

(i) EPA Method 150.1 “pH Electrometric, in Methods for Chemical Analysis of Water and 

Wastes,” 1983, EPA/600/4-79/020. Available on the Internet at http://www.nemi.gov.

(ii) EPA Method 150.2 “pH, Continuous Monitoring (Electrometric), in Methods for Chemical 

Analysis of Water and Wastes,” 1983, EPA/600/4-79/020. Available on the Internet at 

http://www.nemi.gov.

(iii) EPA Method 200.8 “Determination of Trace Elements in Waters and Wastes by Inductively 

Coupled Plasma - Mass Spectrometry,” Revision 5.4, 1994. Available on the Internet at 

https://www.nemi.gov.

(iv) EPA Method 300.0 “Determination of Inorganic Anions by Ion Chromatography Samples,” 

Revision 2.1, 1993. Available on the Internet at http://www.nemi.gov.

(v) EPA Method 300.1 “Determination of Inorganic Anions in Drinking Water by Ion 

Chromatography,” Revision 1.0, 1997. Available on the Internet at 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm.

(vi) EPA Method 317.0 “Determination of Inorganic Oxyhalide Disinfection By-Products in 

Drinking Water Using Ion Chromatography with the Addition of a Postcolumn Reagent for Trace 

Bromate Analysis,” Revision 2.0, 2001, EPA 815-B-01-001. Available on the Internet at 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm.

(vii) EPA Method 326.0 “Determination of Inorganic Oxyhalide Disinfection By-Products in 

Drinking Water Using Ion Chromatography Incorporating the Addition of a Suppressor Acidified

Postcolumn Reagent for Trace Bromate Analysis,” Revision 1.0, 2002, EPA 815-R-03-007. Available on 

the Internet at http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm.

(viii) EPA Method 415.3 “Determination of Total Organic Carbon and Specific UV Absorbance at 

254 nm in Source Water and Drinking Water,” Revision 1.1, 2005, EPA/600/R-05/055. Available on the 

Internet at http://www2.epa.gov/water-research/epa-drinking-water-research-methods
141.35 and 141.40 (a)(1)(i)(A)

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(ix) EPA Method 415.3 “Determination of Total Organic Carbon and Specific UV Absorbance at 

254 nm in Source Water and Drinking Water,” Revision 1.2, 2009, EPA/600/R-09/122. Available on the 

Internet at http://www2.epa.gov/water-research/epa-drinking-water-research-methods.

(x) EPA Method 525.3 “Determination of Semivolatile Organic Chemicals in Drinking Water by 

Solid Phase Extraction and Capillary Column Gas Chromatography/Mass Spectrometry (GC/MS),” 

Version 1.0, February 2012, EPA/600/R-12/010. Available on the Internet at 

http://www2.epa.gov/water-research/epa-drinking-water-research-methods.

(xi) EPA Method 530 “Determination of Select Semivolatile Organic Chemicals in Drinking Water 

by Solid Phase Extraction and Gas Chromatography/Mass Spectrometry (GC/MS),” Version 1.0, January 

2015, EPA/600/R-14/442. Available on the Internet at http://www2.epa.gov/water-research/epadrinking-water-research-methods.

(xii) EPA Method 541 “Determination of 1-Butanol, 1,4-Dioxane, 2-Methoxyethanol and 2-

Propen-1-ol in Drinking Water by Solid Phase Extraction and Gas Chromatography/Mass Spectrometry,” 

November 2015, EPA 815-R-15-011. Available on the Internet at http://www2.epa.gov/waterresearch/epa-drinking-water-research-methods.

(xiii) EPA Method 544 “Determination of Microcystins and Nodularin in Drinking Water by Solid 

Phase Extraction and Liquid Chromatography/Tandem Mass Spectrometry (LC/MS/MS),” Version 1.0, 

February 2015, EPA 600-R-14/474. Available on the Internet at http://www2.epa.gov/waterresearch/epa-drinking-water-research-methods.

(xiv) EPA Method 545 “Determination of Cylindrospermopsin and Anatoxin-a in Drinking Water 

by Liquid Chromatography Electrospray Ionization Tandem Mass Spectrometry (LC/ESI-MS/MS),” April 

2015, EPA 815-R-15-009. Available on the Internet at 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm.

(xv) EPA Method 552.3 “Determination of Haloacetic Acids and Dalapon in Drinking Water by 

Liquid-Liquid Microextraction, Derivatization, and Gas Chromatography with Electron Capture 

Detection,” Revision 1.0, July 2003, EPA 815-B-03-002. Available on the Internet at 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm.

(xvi) 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),” 

Version 1.0, September 2009, EPA 815-B-09-012. Available on the Internet at 

http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods_ogwdw.cfm.

(2) The following methods are from “ASTM International,” 100 Barr Harbor Drive, West 

Conshohocken, PA 19428-2959.

(i) ASTM D1293-12 “Standard Test Methods for pH of Water.” Available for purchase on the 

Internet at http://www.astm.org/Standards/D1293.htm.
141.35 and 141.40 (a)(1)(i)(A)

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(ii) ASTM D5673-10 “Standard Test Method for Elements in Water by Inductively Coupled 

Plasma-Mass Spectrometry,” approved August 1, 2010. Available for purchase on the Internet at 

http://www.astm.org/Standards/D5673.htm.

(iii) ASTM D6581-12 “Standard Test Methods for Bromate, Bromide, Chlorate, and Chlorite in 

Drinking Water by Suppressed Ion Chromatography.” Available for purchase on the Internet at 

http://www.astm.org/Standards/D6581.htm.

(3) The following methods are from “Standard Methods for the Examination of Water & 

Wastewater,” 21st edition (2005), American Public Health Association, 800 I Street NW, Washington, DC 

20001-3710.

(i) SM 2550. “Temperature.”

(ii) SM 3125 “Metals by Inductively Coupled Plasma/Mass Spectrometry.”

(iii) SM 4500-H+ B “pH Value in Water by Potentiometry Using a Standard Hydrogen Electrode.”

(iv) SM 5310B “The Determination of Total Organic Carbon by High-Temperature Combustion 

Method.”

(v) SM 5310C “Total Organic Carbon by Persulfate-UV or Heated-Persulfate Oxidation Method.”

(vi) SM 5310D “Total Organic Carbon by Wet-Oxidation Method.”

(4) The following methods are from “Standard Methods Online.” Available for purchase on the 

Internet at http://www.standardmethods.org.

(i) SM 2550-10 “Temperature.”

(ii) SM 3125-09 “Metals by Inductively Coupled Plasma/Mass Spectrometry (Editorial revisions, 

2011).”

(iii) SM 4500-H+ B-00 “pH Value in Water by Potentiometry Using a Standard Hydrogen 

Electrode.”

(iv) SM 5310B-00 “The Determination of Total Organic Carbon by High-Temperature Combustion 

Method.”

(v) SM 5310C-00 “Total Organic Carbon by Persulfate-UV or Heated-Persulfate Oxidation 

Method.”

(vi) SM 5310D-00 “Total Organic Carbon by Wet-Oxidation Method.”

(5) The following methodology is from Ohio EPA, Columbus, OH.
141.35 and 141.40 (a)(1)(i)(A)

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(i) ELISA SOP. “Ohio EPA Total (Extracellular and Intracellular) Microcystins - ADDA by ELISA 

Analytical Methodology,” Version 2.0, January 2015. Available on the Internet at 

http://www.epa.ohio.gov/Portals/28/documents/habs/HAB_Analytical_Methodology.pdf.

(ii) [Reserved]

[72 FR 393, Jan. 4, 2007; 72 FR 3916, Jan. 26, 2007, as amended at 77 FR 26098, May 2, 2012]