What Is the UCMR? EPA Testing for Unregulated Contaminants

The UCMR is how the EPA finds out whether contaminants it doesn’t regulate yet are turning up in tap water, and how often. For you, it’s a free source of test results for things your utility’s regular compliance testing may not cover. The fifth round, UCMR 5, tested for 29 PFAS and lithium, with full results from about 10,130 water systems.

How do I find my utility’s UCMR 5 results?

Three places, per the EPA’s UCMR 5 page:

• The UCMR 5 Data Finder, searchable by water system name or ID, state or contaminant.
• Your water quality report. Community water systems must list detected UCMR results, with the average and range. Our guide to reading your water quality report shows where.
• A notice from your utility saying results are available, due within 12 months of getting them.

Two tips for reading them. Results are in micrograms per liter (ppb); multiply by 1,000 to get parts per trillion, the unit PFAS limits use. And “<MRL” means the result was below the minimum reporting level (2 to 20 ppt for the PFAS), not necessarily zero. If you can’t find your system, it may serve fewer than 3,300 people and not have been among the 800 small systems sampled.

Does a UCMR result mean my water breaks the law?

No. UCMR results “do not indicate compliance or noncompliance” with the 2024 PFAS limits, the EPA says, because compliance is judged on running annual averages of separate compliance monitoring. They’re a strong hint, though. In its July 2026 data summary, the EPA estimates 7.8% of public water systems nationwide had at least one average above one of the 2024 PFAS limits. If yours is one, ask your utility what it plans to do, and see our PFAS guide for what the numbers mean and when a filter makes sense.

What is UCMR 6?

The next round. The EPA proposed it on July 1, 2026: 30 contaminants, including seven ultrashort organofluorine compounds (some of them PFAS), three pesticide breakdown products and 20 other organic chemicals, with sampling planned from January 2028 through December 2030. Comments closed on August 31, 2026. As of October 10, 2026, it’s a proposal; we found no final rule in the Federal Register.