Is there PFAS in Horsham Water&sewer Authority water?
Yes. EPA's final UCMR 5 results show Horsham Water&sewer Authority averaged 16.9 ppt of PFOS at its worst sampling point, 4.2 times the EPA limit of 4 ppt.
Horsham Water&sewer Authority
Serves 26,000 people · 26 PFOA samples from 11 sampling points · Feb 2024 to Aug 2025
Average above an EPA limit
PFOA Perfluorooctanoic acid
8.8 ppt avg · max 17.5
PFOS Perfluorooctanesulfonic acid
16.9 ppt avg · max 33.8
PFHxS Perfluorohexanesulfonic acid
5.3 ppt avg · max 10.6
Hazard index GenX, PFBS, PFNA, PFHxS combined
0.5 avg · max 1.1
Also detected, no federal limit: PFPeA, PFBA, PFHxA, PFBS, PFHpA.
Horsham Water&sewer Authority is a public water system drawing on surface water, based in Horsham, Pennsylvania, serving about 26,000 people, including Chalfont, Ambler, Hatboro, Horsham, North Wales. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 26 times across 11 sampling points between Feb 2024 and Aug 2025.
Every PFAS detected
Not detected: PFMBA, PFTA, PFTrDA, NEtFOSAA, PFNA, PFDA, PFDoA, 6:2 FTS, NMeFOSAA, PFMPA, 4:2 FTS, HFPO-DA, ADONA, 9Cl-PF3ONS, 11Cl-PF3OUdS, PFUnA, 8:2 FTS, PFEESA, NFDHA, PFPeS, PFHpS.
Lithium, tested in the same program: highest 13.9 ppb, detected in 2 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 Pennsylvania
All 390 tested systems in Pennsylvania
ZIP codes served
18914 19002 19040 19044 19454
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 Horsham Water&sewer Authority water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID PA1460033. https://wellandtap.com/pfas/pennsylvania/horsham-water-and-sewer-authority/
About this data
Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID PA1460033). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.
