Is there PFAS in Sioux City Water Supply water?
Yes. EPA's final UCMR 5 results show Sioux City Water Supply averaged 30.2 ppt of PFHxS at its worst sampling point, 3.0 times the EPA limit of 10 ppt.
Sioux City Water Supply
Serves 85,791 people · 8 PFOA samples from 2 sampling points · Oct 2023 to Jul 2024
Average above an EPA limit
PFOA Perfluorooctanoic acid
2.9 ppt avg · max 6.0
PFOS Perfluorooctanesulfonic acid
2.1 ppt avg · max 4.3
PFHxS Perfluorohexanesulfonic acid
30.2 ppt avg · max 35.0
Hazard index GenX, PFBS, PFNA, PFHxS combined
3.0 avg · max 3.5
Also detected, no federal limit: PFHxA, PFPeA, PFBS, PFPeS, PFBA, PFHpA.
Sioux City Water Supply is a public water system drawing on surface water, based in Sioux City, Iowa, serving about 85,791 people. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 8 times across 2 sampling points between Oct 2023 and Jul 2024.
Every PFAS detected
Not detected: 11Cl-PF3OUdS, PFDA, 9Cl-PF3ONS, PFUnA, PFDoA, PFNA, ADONA, PFTA, PFMBA, NMeFOSAA, NEtFOSAA, PFTrDA, PFHpS, NFDHA, PFEESA, HFPO-DA, PFMPA, 8:2 FTS, 4:2 FTS, 6:2 FTS.
Lithium, tested in the same program: highest 240 ppb, detected in 8 of 8 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 Iowa
All 152 tested systems in Iowa
ZIP codes served
51101 51102 51103 51104 51105 51106 51107 51108 51111
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 Sioux City Water Supply water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID IA9778054. https://wellandtap.com/pfas/iowa/sioux-city-water-supply/
About this data
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID IA9778054). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
