131 California Water Systems Measure PFAS Above the New EPA Limit. The Rest of the Country Combined Has Fewer.

We pulled every PFAS measurement on record for U.S. public water systems — every utility's own reported result, plus the EPA's national testing round — and asked where it's worst.

240 water systems nationwide have measured PFOA, PFOS, PFHxS, or PFNA above the levels the EPA finalized as the first federal PFAS limits in April 2024. 208 of them are mapped on thewatermap.com. 131 are in California.

That's more systems in California alone than in every other state combined.

The states with the most water systems over the new PFAS limit

Rank	State	Systems over the limit
1	California	131
2	Florida	15
3	North Carolina	9
4	Texas	8
5	New Jersey	4
6	Arizona	3
6	Maryland	3
6	Ohio	3
6	South Carolina	3
6	Virginia	3

California's number isn't close. It's more than 8x the next state.

Why — and it's not what you'd assume

Here's the part that changes the story. The EPA ran its own national PFAS sampling round — the fifth Unregulated Contaminant Monitoring Rule (UCMR5), 2023–2025, the same federal data behind our PFAS hotspots leaderboard. Looked at on its own, that round found 80 U.S. water systems over the new limit. Only 17 of them are in California.

So where do California's other 114 systems come from? California's own reporting. California has required its water utilities to test for PFAS and disclose the results since 2020 — years before the EPA's first federal sampling round even started — under the state's own response-level program. Most states don't have an equivalent requirement. They only have whatever the one-time federal UCMR5 window happened to catch.

That's the real finding: California isn't necessarily the most PFAS-contaminated state in the country. It's one of the only states that has been looking. When you require utilities to test, you find more of what's already there. States running on the federal sampling round alone are working from a single snapshot; California utilities have years of their own data.

The worst individual readings

Ranked by how far over the limit, from our full dataset:

System	Location	Compound	Reading	Times over the limit
Riverside Highland Water Company	Riverside, CA	PFHxS	900 ng/L	90x
Corona, City of	Corona, CA	PFOA	300 ng/L	75x
Home Gardens County Water District	Home Gardens, CA	PFOA / PFOS	240 ng/L	60x
Cal-Am Water Company – Duarte	Duarte, CA	PFOA	200 ng/L	50x
San Bernardino Valley Water District	San Bernardino, CA	PFHxS	229 ng/L	22.9x

Four of the five worst readings we found sit within a few miles of each other, in the Riverside–Corona–San Bernardino corridor of California's Inland Empire. We're not asserting a cause here — we don't have source-attribution data — but the geographic clustering is real and visible on the map.

What "over the limit" does and doesn't mean

This is measured data, not an accusation. The EPA finalized PFOA and PFOS limits — 4 parts per trillion each — and PFHxS, PFNA, and GenX limits — 10 ppt each — in April 2024. Utilities have until 2029 to come into full compliance. A system measuring above these numbers today is over the new limit, not yet in a formal violation — the same distinction we drew when we first flagged North Miami Beach's PFAS levels. The number is the story. The framing stays accurate.

See the full list

Every system in this analysis, ranked by how far over the limit it measured, is on the PFAS hotspots leaderboard — sourced from EPA's own lab data, not utility press releases. Search your own city on the map to see whether your water system has PFAS data at all, and what it shows.

PFAS is a federally regulated contaminant with an actual legal limit behind it. Microplastics still aren't — the EPA only added them to its contaminant candidate list in April 2026, the first step toward any standard. If you want to know what's in your water beyond what's currently regulated, that's what our microplastics test kit is for: $50, two tests, results you read yourself in about 15 minutes.