United States
Environmental Protection
M * Agency

The Fifth Unregulated Contaminant Monitoring Rule (UCMR 5)

Program Overview Fact Sheet

What is the Unregulated Contaminant Monitoring Rule (UCMR)?

As part of its responsibilities under the Safe Drinking Water Act (SDWA), the U.S. Environmental Protection
Agency (EPA) implements Section 1445(a)(2), Monitoring Program for Unregulated Contaminants. SDWA
requires that once every five years, EPA issue a list of priority unregulated contaminants to be monitored by
certain public water systems across States, Tribes, and Territories. These contaminants may be present in
drinking water but are not yet subject to EPA drinking water standards. Under the Unregulated Contaminant
Monitoring Rule (UCMR), EPA collects nationally representative drinking water occurrence data to support
EPA's future regulatory determinations and, as appropriate, assist in the development of national primary
drinking water regulations (NPDWRs). For each UCMR cycle, EPA establishes a new list of contaminants for
monitoring, specifies which systems are required to monitor, identifies the sampling locations, and defines the
analytical methods to be used. On December 17, 2021, EPA Administrator Michael Regan signed the final
"Revisions to the Unregulated Contaminant Monitoring Rule (UCMR 5) for Public Water Systems" and the rule
was subsequently published in the Federal Register on December 27, 2021 (86 FR 73131). The 5-year UCMR 5
cycle spans 2022 - 2026, with preparations in 2022, sample collection from 2023 - 2025, and completion of
data reporting in 2026.

Which water systems will participate in UCMR 5?

Section 2021 of America's Water Infrastructure Act of 2018 (AWIA) (Public Law 115-270) amended SDWA and
specifies that, subject to the availability of EPA appropriations for such purpose and sufficient laboratory capacity,
EPA must require all public water systems serving between 3,300 and 10,000 people to monitor and ensure that a
nationally representative sample of systems serving fewer than 3,300 people monitor for the contaminants in
UCMR 5 and future UCMR cycles. Systems serving a population of more than 10,000 people (large systems)
continue to be responsible for participating in the UCMR program.

EPA anticipates approximately one-third of all systems will collect samples each year between 2023 and 2025.
If EPA does not receive the appropriations needed in a given year, EPA will reduce the number of small
systems that will be asked to perform monitoring.

Size Category
(Number of People Served)

Monitoring Design
(CWSs and NTNCWSs)2

Total # of Systems per
Size Category

Small Systems1

(fewer than 3,300)

Nationally representative sample

800

Small Systems1

(3,300-10,000)

All systems, if confirmed by EPA

5,1473

Large Systems

(10,001 and over)

All systems

4,3643

Total

10,311

1.	This requirement is based on the availability of appropriations and sufficient laboratory capacity

2.	Community Water Systems (CWSs), Non-Transient Non-Community Water Systems (NTNCWSs)

3.	Counts are approximate

Office of Water (MS-140)

EPA 815-F-21-009

December 2021


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What contaminants are in UCMR 5?

UCMR 5 specifies monitoring for 29 per- and polyfluoroalkyl substances (PFAS) and lithium listed in the table
below.

Contaminant

CASRN1

MRL2
(l-ig/L)

Additional Information

25 PFAS: EPA Method 533

ll-chloroeicosafluoro-3-oxaundecane-l-sulfonic acid (HCI-PF30UdS)

763051-92-9

0.005



1H,1H, 2H, 2H-perfluorodecane sulfonic acid (8:2FTS)

39108-34-4

0.005



1H,1H, 2H, 2H-perfluorohexane sulfonic acid (4:2FTS)

757124-72-4

0.003



1H,1H, 2H, 2H-perfluorooctane sulfonic acid (6:2FTS)

27619-97-2

0.005



4,8-dioxa-3H-perfluorononanoic acid (ADONA)

919005-14-4

0.003

PFAS are a group of synthetic
chemicals used in a wide range
of consumer products and

9-chlorohexadecafluoro-3-oxanonane-l-sulfonic acid (9CI-PF30NS)

756426-58-1

0.002

hexafluoropropylene oxide dimer acid (HFPO-DA)(GenX)

13252-13-6

0.005

nonafluoro-3,6-dioxaheptanoic acid (NFDHA)

151772-58-6

0.02

industrial applications

perfluoro (2-ethoxyethane) sulfonic acid (PFEESA)

113507-82-7

0.003

including: non-stick cookware,

perfluoro-3-methoxypropanoic acid (PFMPA)

377-73-1

0.004

water-repellent clothing, stain-

perfluoro-4-methoxybutanoic acid (PFMBA)

863090-89-5

0.003

resistant fabrics and carpets,

perfluorobutanesulfonic acid (PFBS)

375-73-5

0.003

cosmetics, firefighting foams,

perfluorobutanoic acid (PFBA)

375-22-4

0.005

electroplating, and products

perfluorodecanoic acid (PFDA)

335-76-2

0.003

that resist grease, water, and
oil. PFAS are found in the blood
of people and animals and in
water, air, fish, and soil at
locations across the United
States and the world.

perfluorododecanoic acid (PFDoA)

307-55-1

0.003

perfluoroheptanesulfonic acid (PFHpS)

375-92-8

0.003

perfluoroheptanoic acid (PFHpA)

375-85-9

0.003

perfluorohexanesulfonic acid (PFHxS)

355-46-4

0.003

perfluorohexanoic acid (PFHxA)

307-24-4

0.003

perfluorononanoic acid (PFNA)

375-95-1

0.004



perfluorooctanesulfonic acid (PFOS)

1763-23-1

0.004



perfluorooctanoic acid (PFOA)

335-67-1

0.004



perfluoropentanesulfonic acid (PFPeS)

2706-91-4

0.004



perfluoropentanoic acid (PFPeA)

2706-90-3

0.003



perfluoroundecanoic acid (PFUnA)

2058-94-8

0.002



4 PFAS: EPA Method 537.1

W-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA)

2991-50-6

0.005



W-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA)

2355-31-9

0.006

See above for PFAS

perfluorotetradecanoic acid (PFTA)

376-06-7

0.008

information.

perfluorotridecanoic acid (PFTrDA)

72629-94-8

0.007



Metal/Pharmaceutical: EPA Method 200.7; SM3 3120 B (2017); SM3 3120 B-99 (1999); ASTM4 D1976-20







Naturally occurring metal that







may concentrate in brine

lithium

7439-93-2

Q

waters; lithium salts are used

Z)

as pharmaceuticals, used in
electrochemical cells, batteries,
and in organic syntheses.

1.	CASRN - Chemical Abstracts Service Registry Number

2.	MRL- Minimum Reporting Level

3.	SM - Standard Methods

4.	ASTM - ASTM International

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Where will samples be collected?

UCMR 5 samples will be collected at entry points to the distribution system (EPTDS) for all contaminants.

•	With prior approval, large ground water systems that have multiple EPTDSs can sample at representative
sampling locations rather than at each EPTDS through a Ground Water Representative Monitoring Plan
(GWRMP).

•	Systems that purchase water with multiple connections from the same wholesaler may select one
representative connection from that wholesaler. The representative EPTDS must be a location within the
purchaser's water system. This EPTDS sampling location must be representative of the highest annual
volume.

What is the sampling frequency and timing?

Water systems will be required to collect samples based on the typical UCMR sampling frequency and
timeframe.

Water Source

Timeframe

Sampling Frequency

Surface water, ground water under
the direct influence of surface
water, or mixed sources systems

Year-Round

Systems must monitor 4 times during a consecutive
12-month monitoring period. Sample events must
occur 3 months apart.

Ground water systems

Year-Round

Systems must monitor 2 times during a consecutive
12-month monitoring period. Sample events must
occur 5-7 months apart.

What does UCMR 5 participation involve? Who pays?

All systems required to participate in UCMR 5 will collect samples. As with previous UCMRs, large systems
make arrangements with approved laboratories and pay for their own sample shipping and analytical costs;
EPA arranges for the analysis of small-system samples and pays for shipping and analytical costs. All
laboratories conducting analyses for UCMR 5 must receive EPA approval to perform those analyses (UCMR
Laboratory Approval Program).

How did EPA select the UCMR 5 contaminants?

The National Defense Authorization Act for Fiscal Year 2020 (NDAA) specifies that EPA shall include all PFAS in
UCMR 5, for which a drinking water method has been validated by the Administrator and that are not subject
to an NPDWR. Accordingly, UCMR 5 includes all 29 PFAS that are within the scope of EPA Methods 533 and
537.1, as well as lithium. In evaluating contaminants for UCMR 5, EPA considered the fourth Contaminant
Candidate List (CCL 4) as well as contaminants nominated by the public for potential inclusion on the fifth CCL
(CCL 5) and other priority contaminants.

EPA selected UCMR contaminants using a multi-step prioritization process. The first step identified
contaminants that were not monitored under previous UCMR cycles; may have significant occurrence
nationally; and have a completed, validated drinking water method. The next step focused on contaminants
associated with one or more of the following considerations: an available health assessment to facilitate
regulatory determinations; high public concern; critical health endpoints (for example, a likely or suggestive
carcinogen); active use (for example, pesticides); and/or an occurrence data gap. Then EPA considered
stakeholder input; looked at cost-effectiveness of analytical methods (single methods that address multiple
contaminants of interest); considered implementation factors (such as laboratory capacity); and further
considered available health data (e.g., children), occurrence data, and persistence/mobility data.

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What are the public health benefits of the UCMR program?

The UCMR program provides EPA and other interested parties with nationally representative occurrence data
on emerging contaminants in drinking water. The data can be used to support EPA's regulatory determinations
and may support additional actions to protect public health.

The public benefits from the information about whether or not unregulated contaminants are present in their
drinking water. If contaminants are not found, consumer confidence in their drinking water should improve. If
contaminants are found, related health effects may be avoided when subsequent actions, such as regulations,
are implemented, reducing or eliminating those contaminants.

Where can consumers find UCMR results?

All systems are required to report their data to EPA. The analytical results from UCMR are stored in the
National Contaminant Occurrence Database (NCOD) for drinking water. For a summary of the UCMR results,
tips for querying NCOD, and health effects information (including reference concentrations), please refer to
the UCMR Occurrence Data webpage.

The Public Notification Rule requires that all systems notify their customers of the availability of UCMR results
no later than 12-months after results are known. Community Water Systems (CWSs) are also required to
report UCMR results in their annual Consumer Confidence Report (CCR) when unregulated contaminants are
detected (the CCR Rule does not apply to non-community water systems). CWSs may include their public
notice within CCRs, also known as annual drinking water quality reports, which are to be delivered to all billing
customers by July 1 of each year. CWSs must report the average of the year's monitoring results and the range
of detections. To obtain a copy of their CCR, consumers may check their water bill for information or contact
their water supplier. Additional information about the CCR including details on reporting requirements can be
found on the CCR Homepage.

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What are the key deadlines and requirements?

Due Date

Requirement

Report
via
SDWARS1

Following Rule Publication on December 27, 2021

August 1, 2022

Laboratories seeking approval must complete and submit the necessary
registration form and application materials in order to participate in the
laboratory approval process. Contact UCMR Lab Approval@epa.gov
for more information.



December 31, 2022

Large systems must register for EPA's web-based reporting system
"SDWARS", accept their notification letter, and update sampling
location(s) and zip code(s). If applicable, the system may update their
monitoring schedule. After December 31, 2022, large systems must
contact UCMR Sampling Coordinator@epa.gov to request any
changes.

X

December 31, 2022

Small systems must register for SDWARS, accept their notification letter
and update sampling location(s), shipping address, and zip code(s).
Systems must provide an explanation and obtain approval for any
requested monitoring schedule change. Contact the UCMR Message
Center at UCMR5@glec.com for more information.

X

6 months prior to
the water system's
scheduled sample
collection

Large ground water systems (or large surface water systems with
ground water sources) that wish to monitor from representative
EPTDSs may submit a ground water representative monitoring plan
(GWRMP) approved under a prior UCMR cycle or a proposal for a new
representative sampling plan. Systems scheduled for sample collection
in 2023 are encouraged to submit plans by December 31, 2022, to allow
time for review by EPA and, as appropriate, the State. Contact
UCMR Sampling Coordinator@epa.gov for more information.



Following Sample Collection

Within 90 days of
sample collection

Laboratories post data to SDWARS.

X

Within 30 days of
laboratory posting
data

Large water systems review and approve the data. If the system has
not acted upon the data after 30 days, the data are considered
approved and ready for state and EPA review.

X

1. Safe Drinking Water Accession and Review System (SDWARS).

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What are the data elements EPA will collect?

EPA will collect the following information in EPA's web-based data reporting system, SDWARS.

Public Water System
Identification (PWSID) Code

Disinfectant Type

Analysis Date

Public Water System Name

Treatment Information

Sample Analysis Type

Public Water System Facility
Identification Code

Sample Collection Date

Analytical Result-Sign

Public Water System Facility Name

Sample Identification Code

Analytical Result-Measured Value

Public Water System Facility Type

Contaminant

Additional Value

Water Source Type

Analytical Method Code

Laboratory Identification Code

Sampling Point Identification Code

Extraction Batch Identification
Code

Sample Event Code

Sampling Point Name

Extraction Date

Historical Information for
Contaminant Detections and
Treatment

Sampling Point Type Code

Analysis Batch Identification Code

Potential PFAS Sources

Where can I find more information?

•	Safe Drinking Water Information Website for information on how to submit drinking water comments
or questions to EPA Office of Ground Water and Drinking Water

•	UCMR Website for information on current and past UCMRs, occurrence data, and public meetings

•	EPA Ground Water and Drinking Water Website for information on source water protection, drinking
water regulations, monitoring requirements for States and systems, SDWA on Tribal lands, and
laboratory certification

•	EPA PFAS Website for information on the Agency's actions to address PFAS

Questions?

•	Contact the UCMR Message Center at UCMR5@glec.com for general information about monitoring
requirements or navigating SDWARS

•	Contact UCMR Sampling Coordinator@epa.gov for changes to large water system inventory and/or
schedule after December 31, 2022

•	Contact UCMR Lab Approval@epa.gov for information on the laboratory approval program and
general laboratory support

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