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Is there PFAS in Chelmsford Water District water?

Yes. EPA's final UCMR 5 results show Chelmsford Water District averaged 7.5 ppt of PFOA at its worst sampling point, 1.9 times the EPA limit of 4 ppt.

Chelmsford Water District Serves 28,750 people · 8 PFOA samples from 4 sampling points · Oct 2023 to Oct 2024 Average above an EPA limit
PFOA Perfluorooctanoic acid 7.5 ppt avg · max 8.9
EPA 4
PFOS Perfluorooctanesulfonic acid 5.7 ppt avg · max 7.2
EPA 4
Hazard index GenX, PFBS, PFNA, PFHxS combined not detected
EPA 1

Also detected, no federal limit: PFBS, PFPeA, PFHxA.

Averages are for the worst sampling point, with non-detects counted as zero. Source: EPA UCMR 5.

Chelmsford Water District is a public water system drawing on groundwater, based in Chelmsford, Massachusetts, serving about 28,750 people. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 8 times across 4 sampling points between Oct 2023 and Oct 2024.

Every PFAS detected

PFAS Detected Highest Worst point avg EPA limit
PFOA
Perfluorooctanoic acid		 7 of 8 8.9 ppt 7.5 ppt 4 ppt
PFOS
Perfluorooctanesulfonic acid		 5 of 8 7.2 ppt 5.7 ppt 4 ppt
PFBS
Perfluorobutanesulfonic acid		 1 of 8 4.2 ppt 2.1 ppt none
PFPeA
Perfluoropentanoic acid		 5 of 8 3.7 ppt 3.5 ppt none
PFHxA
Perfluorohexanoic acid		 7 of 8 3.5 ppt 3.4 ppt none

Not detected: PFDoA, ADONA, NMeFOSAA, PFUnA, 11Cl-PF3OUdS, 9Cl-PF3ONS, HFPO-DA, PFBA, 6:2 FTS, 4:2 FTS, PFMPA, PFTA, PFMBA, 8:2 FTS, NFDHA, PFTrDA, PFHpA, PFHxS, PFPeS, NEtFOSAA, PFEESA, PFNA, PFDA, PFHpS.

Lithium, tested in the same program: not detected.

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 Massachusetts

All 263 tested systems in Massachusetts

ZIP codes served

01824

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 Chelmsford Water District water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID MA3056000. https://wellandtap.com/pfas/massachusetts/chelmsford-water-district/

About this data

Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID MA3056000). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.