Some. At least one sample reached an EPA limit, but the average at every sampling point stayed below it.
California Water Service - Stockton is a public water system drawing on surface water, based in San Jose, California, serving about 176,266 people, including Stockton, French Camp. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 28 times across 12 sampling points between Jan 2025 and Mar 2026.
| PFAS | Detected | Highest | Worst point avg | EPA limit |
|---|---|---|---|---|
| PFOS Perfluorooctanesulfonic acid |
2 of 28 | 5.2 ppt | 2.6 ppt | 4 ppt |
Not detected: PFBA, 6:2 FTS, 4:2 FTS, 8:2 FTS, PFMPA, PFPeA, PFMBA, PFEESA, PFPeS, HFPO-DA, PFHxS, NEtFOSAA, PFTA, NFDHA, ADONA, 9Cl-PF3ONS, 11Cl-PF3OUdS, PFUnA, PFHxA, PFDoA, PFDA, PFOA, PFNA, PFHpA, PFBS, NMeFOSAA, PFTrDA, PFHpS.
Lithium, tested in the same program: not detected.
In April 2024 EPA set enforceable limits of 4 ppt for PFOA and PFOS, 10 ppt each for PFHxS, PFNA and GenX, and a hazard index of 1 for mixtures. Utilities were given until 2029 to comply. In May 2026 EPA proposed keeping only the PFOA and PFOS limits and moving that deadline to 2031. Until that proposal is final, the 2024 limits stand.
Compliance is judged on a running annual average at each entry point, so we show the average at this system's worst sampling point next to its single highest result. UCMR 5 results do not by themselves put a utility in or out of compliance.
Two routes work for PFAS. For drinking and cooking water only, a reverse osmosis system certified to NSF/ANSI 58 with a PFOA/PFOS reduction claim is the cheapest proven option. To treat every tap and shower, a whole-house carbon system with enough contact time works, but check that the maker has PFAS test data, not just a marketing claim. See the best filters for PFAS and how PFAS removal works.
All 707 tested systems in California
95202 95203 95204 95205 95206 95207 95210 95211 95212 95215 95219 95231
As reported by the utility to EPA. Neighbouring ZIPs are often split between systems; your water bill names yours.
Well & Tap. "PFAS in California Water Service - Stockton water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID CA3910001. https://wellandtap.com/pfas/california/california-water-service-stockton/
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID CA3910001). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
