Yes. EPA's final UCMR 5 results show Aquarion Water CO of Ct-greenwich System averaged 4.9 ppt of PFOA at its worst sampling point, 1.2 times the EPA limit of 4 ppt.
Also detected, no federal limit: PFHxA, PFPeA.
Aquarion Water CO of Ct-greenwich System is a public water system drawing on surface water, based in Shelton, Connecticut, serving about 53,297 people, including Cos Cob, Greenwich, Old Greenwich, Riverside. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 12 times across 2 sampling points between Oct 2024 and Aug 2025.
| PFAS | Detected | Highest | Worst point avg | EPA limit |
|---|---|---|---|---|
| PFOA Perfluorooctanoic acid |
11 of 12 | 5.6 ppt | 4.9 ppt | 4 ppt |
| PFOS Perfluorooctanesulfonic acid |
2 of 12 | 4.1 ppt | 1.0 ppt | 4 ppt |
| PFHxA Perfluorohexanoic acid |
6 of 12 | 4.0 ppt | 2.1 ppt | none |
| PFPeA Perfluoropentanoic acid |
2 of 12 | 3.8 ppt | 0.9 ppt | none |
Not detected: PFMPA, PFTA, PFHpS, PFPeS, NFDHA, PFEESA, PFMBA, 8:2 FTS, 6:2 FTS, PFBA, HFPO-DA, ADONA, 4:2 FTS, 11Cl-PF3OUdS, PFDA, PFNA, PFHxS, PFHpA, PFBS, 9Cl-PF3ONS, PFDoA, PFUnA, NMeFOSAA, NEtFOSAA, PFTrDA.
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 63 tested systems in Connecticut
06807 06830 06831 06870 06878
As reported by the utility to EPA. Neighbouring ZIPs are often split between systems; your water bill names yours.
Well & Tap. "PFAS in Aquarion Water CO of Ct-greenwich System water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID CT0570011. https://wellandtap.com/pfas/connecticut/aquarion-water-co-of-ct-greenwich-system/
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID CT0570011). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
