No PFAS were detected in any of the 8 samples EPA's program collected.
St Louis City Pws is a public water system drawing on surface water, based in St Louis, Missouri, serving about 304,709 people, including Chesterfield, Saint Louis. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 8 times across 2 sampling points between Mar 2024 and Dec 2024.
None of the 29 PFAS were found at or above EPA's minimum reporting levels (2 to 20 ppt depending on the compound).
Not detected: PFPeA, ADONA, HFPO-DA, PFBA, 6:2 FTS, 4:2 FTS, PFMPA, PFMBA, PFEESA, 9Cl-PF3ONS, PFPeS, PFBS, NFDHA, 8:2 FTS, 11Cl-PF3OUdS, PFUnA, PFHxA, PFDoA, PFOA, PFNA, PFHpA, NMeFOSAA, NEtFOSAA, PFTrDA, PFTA, PFDA, PFHpS, PFHxS, PFOS.
Lithium, tested in the same program: highest 45.3 ppb, detected in 8 of 8 samples. EPA's health-based screening level is 10 ppb.
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.
No PFAS action is needed on these results. If your water tastes or smells of chlorine, a whole-house city water filter is the usual fix.
All 232 tested systems in Missouri
63017 63101 63102 63103 63104 63105 63106 63107 63108 63109 63110 63111 63112 63113 63115 63116 63117 63118 63119 63120 63123 63125 63130 63133 63136 63137 63139 63143 63147 63155
As reported by the utility to EPA. Neighbouring ZIPs are often split between systems; your water bill names yours.
Well & Tap. "PFAS in St Louis City Pws water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID MO6010715. https://wellandtap.com/pfas/missouri/st-louis-city-pws/
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID MO6010715). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
