PFAS in Tap Water: More Than 1,700 U.S. Water Systems Logged PFOA or PFOS at or Above 4 Parts Per Trillion in EPA Monitoring, Newsweek Map Shows

More than 1,700 U.S. public water systems recorded at least one PFOA or PFOS result at or above 4 parts per trillion (ppt) in federal monitoring, according to a map Newsweek published on October 21, 2026. Four ppt is the federal Maximum Contaminant Level (MCL) for each of those two PFAS chemicals in drinking water. The results come from the EPA’s fifth Unregulated Contaminant Monitoring Rule (UCMR 5), which required certain public water systems to monitor for 29 PFAS between 2023 and 2025; the EPA released the final dataset in August 2026.

What a single reading does and does not mean

• Not a violation by itself. An individual UCMR 5 reading at or above 4 ppt does not mean a system violated federal standards, Newsweek noted. Compliance is judged on running annual averages from separate compliance monitoring, and the EPA says UCMR 5 results “do not indicate compliance or noncompliance with the MCLs.”
• EPA’s own averages. In its July 2026 UCMR 5 Data Summary, the EPA averaged results where it could for about 10,130 systems with full sets of results at about 25,950 sampling locations. It found averages above at least one PFAS MCL at 15.5% of large systems (662 of 4,277, serving more than 10,000 people), 8.3% of medium systems (419 of 5,077) and 7.1% of small systems (55 of 775). Its weighted estimate for systems nationwide is 7.8%.
• PFOS and PFOA lead. Of the six PFAS in the 2024 rule, PFOS and PFOA had by far the most system averages above their limits in the EPA’s table: 523, 307 and 45 large, medium and small systems for PFOS, and 472, 273 and 34 for PFOA.
• Often more than one. PFAS show up as mixtures: 66% of sampling locations with at least one PFAS at or above the UCMR 5 reporting level had results for more than one PFAS, the EPA says.

The deadline question

On May 18, 2026, the EPA proposed keeping the PFOA and PFOS limits while letting eligible systems request two more years to comply, which would move the deadline from 2029 to 2031, and proposed rescinding the limits for PFHxS, PFNA, HFPO-DA (GenX) and the Hazard Index mixture. Newsweek reported that the extension has not been finalized; the public comment period closed July 20.

How to check your own water

The EPA’s UCMR 5 Data Finder lets anyone search results by water system, state or contaminant. Community water systems also have to report UCMR results that were found at or above reporting levels in their annual Consumer Confidence Report, the drinking water quality report delivered to billing customers each year by July 1, according to the EPA.

Why WaterVO™ follows this

These numbers describe water drawn from wells, rivers and lakes before and after treatment. Atmospheric water generation, which we call vapor optimizing (VO), starts from a different source: it filters incoming air and condenses drinking water from humidity instead. We believe VO is likely the best option for drinking water. It uses energy, but we think cleaner drinking water is worth it.

Sources

• Alice Gibbs, “Map Shows US Drinking Water Contaminated With ‘Forever Chemicals’,” Newsweek, October 21, 2026: newsweek.com
• U.S. EPA, “Data Summary of the Fifth Unregulated Contaminant Monitoring Rule (UCMR 5),” July 2026 (815-S-26-007): epa.gov
• U.S. EPA, “Fifth Unregulated Contaminant Monitoring Rule” (read Oct. 22, 2026): epa.gov
• U.S. EPA, “Per- and Polyfluoroalkyl Substances (PFAS)” drinking water rule page (read Oct. 22, 2026): epa.gov

Photo: filling a glass with water at a kitchen sink, by Shixart1985 via Wikimedia Commons (CC BY 2.0); cropped, headline added in the featured image. Illustrative; not a photo of any water system in the data.

Keep learning

More from WaterVO News: PFAS treatment comes online in Bridgewater, Mass., returning two wells · PFAS limits of 4 parts per trillion: New York bill awaits Gov. Hochul’s signature

Go deeper with the water experts at Hydrology University: the PFAS guide.

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