Yes, at low levels. 1 PFAS was detected, all below EPA's 2024 limits.
Also detected, no federal limit: PFBA.
Mo American St Louis St Charles Counties is a public water system drawing on surface water, based in Chesterfield, Missouri, serving about 1.1 million people, including Chesterfield, Ballwin, Eureka, Fenton, Florissant, Glencoe. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 24 times across 6 sampling points between Mar 2024 and Dec 2024.
| PFAS | Detected | Highest | Worst point avg | EPA limit |
|---|---|---|---|---|
| PFBA Perfluorobutanoic acid |
2 of 24 | 5.1 ppt | 1.3 ppt | none |
Not detected: PFNA, PFHxS, PFHpA, PFBS, PFHpS, PFPeS, NFDHA, PFEESA, 8:2 FTS, 9Cl-PF3ONS, 4:2 FTS, PFPeA, PFOS, PFOA, PFDA, PFDoA, PFHxA, 11Cl-PF3OUdS, PFTA, PFTrDA, NEtFOSAA, NMeFOSAA, 6:2 FTS, PFMPA, PFUnA, HFPO-DA, ADONA, PFMBA.
Lithium, tested in the same program: highest 86.8 ppb, detected in 16 of 24 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.
Levels here are under EPA's limits, so no treatment is required. If you want them lower anyway, a certified reverse osmosis system under the sink handles drinking water, and a whole-house carbon filter also takes out the chlorine or chloramine your utility adds.
All 232 tested systems in Missouri
63005 63006 63011 63017 63021 63025 63026 63031 63032 63033 63034 63038 63040 63042 63043 63044 63045 63074 63088 63099 63105 63114 63117 63119 63121 63122 63123 63124 63125 63126 63127 63128 63129 63130 63131 63132 63133 63134 63135 63136 63137 63138 63140 63141 63143 63144 63145 63146
As reported by the utility to EPA. Neighbouring ZIPs are often split between systems; your water bill names yours.
Well & Tap. "PFAS in Mo American St Louis St Charles Counties water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID MO6010716. https://wellandtap.com/pfas/missouri/mo-american-st-louis-st-charles-counties/
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID MO6010716). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
