Is there PFAS in City of Ripon water?

Yes. EPA's final UCMR 5 results show City of Ripon averaged 12.0 ppt of PFOS at its worst sampling point, 3.0 times the EPA limit of 4 ppt.

City of Ripon is a public water system drawing on groundwater, based in Ripon, California, serving about 15,741 people. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 10 times across 5 sampling points between Jul 2024 and Jan 2025.

Every PFAS detected

Not detected: 9Cl-PF3ONS, NMeFOSAA, PFUnA, PFHpA, PFNA, PFDA, PFDoA, 11Cl-PF3OUdS, ADONA, HFPO-DA, PFBA, 6:2 FTS, PFTrDA, PFHxA, PFTA, 4:2 FTS, NEtFOSAA, PFHpS, PFPeS, PFEESA, PFMBA, PFPeA, PFMPA, 8:2 FTS, NFDHA, PFBS.

Lithium, tested in the same program: highest 9.9 ppb, detected in 2 of 10 samples. EPA's health-based screening level is 10 ppb.

What the EPA limits mean here

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.

What you can do at home

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.

Other systems in California

• Us Army Fort Irwin none detected
• Cal Am - Fruitridge Vista none detected
• City of La Palma none detected
• Carpinteria Valley Water District none detected
• Rio Linda/elverta Community Water Dist 2 PFAS detected
• Northstar C.s.d. none detected

All 707 tested systems in California

ZIP codes served

95366

As reported by the utility to EPA. Neighbouring ZIPs are often split between systems; your water bill names yours.

Cite this page

Well & Tap. "PFAS in City of Ripon water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID CA3910007. https://wellandtap.com/pfas/california/city-of-ripon/

About this data

Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID CA3910007). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.