Is there PFAS in Arapahoe Cnty Wwwa water?
Some. At least one sample reached an EPA limit, but the average at every sampling point stayed below it.
Arapahoe Cnty Wwwa
Serves 31,000 people · 14 PFOA samples from 7 sampling points · Feb 2023 to Jan 2024
One or more samples at an EPA limit
PFOA Perfluorooctanoic acid
2.3 ppt avg · max 4.6
PFOS Perfluorooctanesulfonic acid
not detected
Hazard index GenX, PFBS, PFNA, PFHxS combined
not detected
Also detected, no federal limit: PFPeA, PFHxA, PFBS, PFBA.
Arapahoe Cnty Wwwa is a public water system drawing on groundwater, based in Centennial, Colorado, serving about 31,000 people, including Aurora, Englewood. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 14 times across 7 sampling points between Feb 2023 and Jan 2024.
Every PFAS detected
Not detected: PFOS, PFTA, 9Cl-PF3ONS, ADONA, HFPO-DA, 6:2 FTS, 4:2 FTS, 8:2 FTS, PFMPA, PFMBA, PFEESA, NFDHA, PFDA, PFHpS, PFTrDA, NEtFOSAA, NMeFOSAA, PFHpA, PFHxS, PFNA, PFDoA, PFUnA, 11Cl-PF3OUdS, PFPeS.
Lithium, tested in the same program: highest 23.2 ppb, detected in 14 of 14 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
80015 80016 80111 80112
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 Arapahoe Cnty Wwwa water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID CO0203002. https://wellandtap.com/pfas/colorado/arapahoe-cnty-wwwa/
About this data
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID CO0203002). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
