Washington PFAS results from EPA's final data

Report published Nov 14, 2026 · EPA UCMR 5 final data file of Oct 15, 2026 (samples collected 2023–2025) · Method · National results →

20 Washington water systems serving 1.2 million people had PFAS above a 2024 federal limit in EPA's final round of nationwide PFAS testing: 8% of the 245 Washington systems tested, compared with 11% nationally.

Highest PFOA or PFOS averages in Washington

Largest systems above a limit

All 20 Washington systems above a limit

Every Washington community water system whose UCMR 5 results averaged above a 2024 federal PFAS limit, largest first. Systems that were not tested are not listed: not tested is not the same as not detected.

The same list, with PFOA and PFOS averages, is in the data download.

Which limits were exceeded

"–" in the table above means not detected. A system can be above more than one limit. EPA proposed in May 2026 to rescind the PFHxS, PFNA, GenX and Hazard Index limits. That proposal is not final.

Washington has its own PFAS rules. WAC 246-290-315 Table 9 SALs (plus Hazard Index 1) trigger mandatory follow-up under WAC 246-290-320. SALs are not state MCLs. Details. This report compares results with the federal limits only.

Data and how to cite it

• Download every Washington water system as CSV (PFOA and PFOS averages, systems above a limit, lead, violations).
• EPA's source file: UCMR 5 occurrence data.

Suggested citation:

Tap Water Results, "Washington PFAS results from EPA's final UCMR 5 data" (published Nov 14, 2026, EPA data file of Oct 15, 2026). https://tapwaterresults.com/pfas/washington/

You're welcome to quote and republish these figures with a link back. Questions from reporters: see contact.

Method

For each system we average each entry point's UCMR 5 results (non-detects count as zero, complete sets of samples only) and compare the highest entry-point average with the 2024 federal limit, using EPA's rounding. This is how EPA compares UCMR 5 results to the limits in its own data summary, and our national counts match EPA's published table within 2% (how we check). Results are monitoring data from 2023–2025, not compliance determinations, and treatment installed since then is not reflected. Full method.

All Washington water systems → · National results → · PFAS results for every state →

Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.