Is there PFAS in Parker WSD water?
Some. At least one sample reached an EPA limit, but the average at every sampling point stayed below it.
Parker WSD
Serves 75,949 people · 26 PFOA samples from 11 sampling points · Apr 2024 to Jul 2025
One or more samples at an EPA limit
PFOA Perfluorooctanoic acid
1.2 ppt avg · max 4.8
PFOS Perfluorooctanesulfonic acid
not detected
Hazard index GenX, PFBS, PFNA, PFHxS combined
not detected
Also detected, no federal limit: PFPeA, PFHxA, PFBA, PFBS.
Parker WSD is a public water system drawing on surface water, based in Parker, Colorado, serving about 75,949 people, including Castle Rock, Englewood, Lone Tree, Parker. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 26 times across 11 sampling points between Apr 2024 and Jul 2025.
Every PFAS detected
Not detected: 9Cl-PF3ONS, PFPeS, NFDHA, PFEESA, PFMBA, PFMPA, 8:2 FTS, 4:2 FTS, 6:2 FTS, PFTrDA, ADONA, PFTA, 11Cl-PF3OUdS, PFUnA, PFDoA, PFDA, PFOS, PFNA, PFHxS, PFHpA, HFPO-DA, NMeFOSAA, NEtFOSAA, PFHpS.
Lithium, tested in the same program: highest 27.6 ppb, detected in 26 of 26 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 Colorado
All 165 tested systems in Colorado
ZIP codes served
80108 80112 80124 80134 80138
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 Parker WSD water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID CO0118040. https://wellandtap.com/pfas/colorado/parker-wsd/
About this data
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID CO0118040). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
