EPA’s Fifth Unregulated Contaminant Monitoring Rule (UCMR 5)
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Through the years, Pace® has analyzed tens of thousands of samples under the EPA’s Unregulated Contaminant Monitoring Rule (UCMR) drinking water monitoring program. As UCMR 5 drinking water sampling draws to a close, we’re pleased to share insights and observations from our work with public water systems across the country.
WHAT IS UCMR 5?
The EPA’s Unregulated Contaminant Monitoring Rule (UCMR) is designed to collect data on contaminants that are suspected to be present in drinking water but do not yet have health-based standards set under the Safe Drinking Water Act (SDWA). A revised list of 30 contaminants is selected every five years. UCMR 5 is the fifth UCMR round to be implemented.
WATCH THE UCMR 5 WEBINAR
Pace® conducted a national technical briefing for PFAS and UCMR 5. The replay is now available on demand.
UCMR 5 TIMELINE
Sampling for UCMR 5 will run from January 1, 2023, through December 31, 2025. Sampling and reporting requirements can be found on the EPA’s UCMR 5 website. If this is your first time participating in a UCMR program or you need help understanding some of the new rules, please reach out to our UCMR 5 experts. Pace® has been an approved UCMR lab since UCMR 3, and we are here to help with your UCMR 5 testing needs and questions.COVERED WATER SYSTEMS UNDER UCMR 5
All PWS serving more than 3300 people and a randomly selected set of 800 smaller systems will be required to comply with UCMR. This more than doubles the number of water systems required to participate.
UCMR 5 CONTAMINANTS
The UCMR 5 contaminant list includes 29 PFAS compounds plus the metal lithium. The number of PFAS included shows just how serious the EPA is about monitoring PFAS in the nation’s drinking water. The list of compounds, along with their corresponding CAS# can be found on the EPA’s UCMR 5 fact sheet.
UCMR 5 TEST METHODS
To analyze for all 30 contaminants, UCMR 5 requires three EPA validated test methods. Both EPA Test Methods 537.1 and 533 are required to analyze for the 29 PFAS compounds, and EPA Test Method 200.7 will be required to analyze for lithium. Pace® is approved for all three methods.
UCMR 5 SAMPLING POINTS
UCMR 5 requires fewer sampling points than prior UCMR rounds. Sampling is only required at the entry point to each distribution system and will not include distribution system locations. Sampling of source water will not be required in UCMR 5. More details can be found on the EPA’s UCMR 5 guidance page.
UCMR 5 COST OF TESTING
The EPA has estimated the cost of UCMR 5 testing to be around $950 per sample. Large PWS’s will be required to cover the cost of testing themselves. Pending budget availability, the EPA has the intent to cover all of the testing costs for the small PWS’s (< 10,000 people served) that are required to participate in UCMR 5. Pace® is available to assist large PWS operators in assessing their UCMR 5 testing requirements and creating a budget.Additional UCMR FAQs
Q: How can I find a UCMR drinking water laboratory near me?
If for some reason you need to find a new EPA-approved UCMR laboratory to finish up your required UCMR 5 sampling, reach out to us. Pace® operates several EPA and state-approved laboratories across the country and would be happy to put you in touch with one that has the capabilities and capacity to meet your testing needs.
Q: Where can I find results from UCMR 5 drinking water sampling?
Occurrence data from UCMR 5 drinking water sampling is available on the EPA’s dedicated UCMR 5 Data Finder webpage. This site provides updated national occurrence data summaries and detailed monitoring results reported by public water systems. The EPA website also offers downloadable data files and interactive dashboards, allowing you to search for results by contaminant, water system, or location. For more in-depth analysis, summary reports and technical documents related to UCMR 5 are made available alongside the raw sampling data on the EPA’s Unregulated Contaminant Monitoring Rule site.
Q: Does UCMR set limits on PFAS in drinking water?
UCMR does not set enforceable limits, but instead, requires public water systems to monitor and report concentrations of individual PFAS (UCMR 3 and UCMR 5) and other emerging contaminants in drinking water, supplying the EPA with comprehensive occurrence data to guide regulatory decision-making. When the EPA determines a contaminant should be regulated based on the evidence gathered through UCMR monitoring and other sources, it can establish legally enforceable Maximum Contaminant Levels (MCLs) under the National Primary Drinking Water Regulations (NPDWR).
Q: Why are there regulated PFAS in an unregulated contaminant monitoring program?
NPDWR for certain PFAS were finalized after UCMR 5 drinking water sampling had already begun. Although the EPA has not stated that UCMR 5 drinking water sampling led to its decision to limit enforceable MCLs under the NPDWR to PFOA and PFOS, continued monitoring as part of UCMR helped provide comprehensive occurrence data to support the agency’s regulatory reviews.
Q: How long do we have to address elevated levels of PFAS?
Under the current NPDWR finalized in 2024, water systems must complete Initial Monitoring by April 2027 and achieve compliance with the MCLs for regulated PFAS by 2029. In May 2025, the EPA announced plans to extend the compliance deadline by two additional years, giving water systems until 2031 to meet PFAS drinking water standards due to operational and implementation challenges.
If you need to address elevated levels of PFAS in drinking water, the Pace® PFAS Treatability Studies Center of Excellence can help. Contact us to start a discussion.
Q: Will UCMR 6 Include Additional PFAS?
UCMR 6 is expected to focus on emerging contaminants listed in the EPA’s Contaminant Candidate List 5 (CCL 5). This list includes microplastics, additional PFAS compounds (e.g., certain ultra-short-chain PFAS, PFAS precursors, intermediates, and byproducts), and other priority chemicals. Many observers believe that microplastics are a strong candidate for UCMR 6 due to growing public health concerns and recent advocacy from environmental organizations.
At present, the two currently available EPA-approved drinking water test methods, EPA 533 and EPA 537.1, are only validated for the 29 PFAS included in UCMR 5. The EPA is working on a new drinking water method, currently designated EPA 534, that uses direct injection and Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS). Along with other advantages over current methods, once finalized, this method may expand the number of targeted analytes. However, the timing of its availability may or may not fit into the development cycle of UCMR 6. The EPA’s most recent timeline (developed in 2024 under the previous administration) includes publishing the UCMR 6 proposal for public comment and a host of other activities by mid-late 2025. The timeline lists that EPA will publish the final rule by late 2026, pre-monitoring implementation will continue through 2027, and the 3-year sampling period will take place from January 2028 through December 2030.
It’s important to note that the EPA does not need to limit the list of contaminants in UCMR 6 to only those included in CCL 5. It has the flexibility to consider contaminants from previous CCLs, anticipate new priorities being considered for CCL 6, or select substances based on emerging health concerns or stakeholder input. For example, some pesticides and disinfection byproducts were included in earlier UCMR cycles ahead of their formal addition to a CCL. This approach allows the UCMR program to adapt to evolving scientific knowledge, environmental concerns, and monitoring capabilities.
REASONS TO CHOOSE PACE®
EXPERIENCED
Pace® has been an industry leader in persistent organic pollutant testing for over three decades.
CERTIFIED
We’re certified/accredited by NELAC, ISO, DOD, DOE, and in every state with a PFAS lab certification program.
RELIABLE
For emergencies, our Rapid Response Team can provide defensible results in as little as 24 hours.
COMMITTED
We are committed to helping our customers advance their important work through building strong relationships, delivering upon expectations, and providing exceptional customer service.
ADVANCED
We can test for PFAS in both solid and aqueous matrices, including potable and non-potable waters, soils, and biota.
INNOVATIVE
We’re on the leading edge of science, working with EPA, DOD, ASTM, and others to develop new methods for analyzing PFAS.
