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Is there PFAS in Natick Water Department water?

Yes. EPA's final UCMR 5 results show Natick Water Department averaged 32.2 ppt of PFOS at its worst sampling point, 8.1 times the EPA limit of 4 ppt.

Natick Water Department Serves 37,006 people · 8 PFOA samples from 4 sampling points · Dec 2024 to Jun 2025 Average above an EPA limit
PFOA Perfluorooctanoic acid 12.0 ppt avg · max 14.3
EPA 4
PFOS Perfluorooctanesulfonic acid 32.2 ppt avg · max 37.3
EPA 4
PFHxS Perfluorohexanesulfonic acid 7.6 ppt avg · max 11.2
EPA 10
Hazard index GenX, PFBS, PFNA, PFHxS combined 0.8 avg · max 1.1
EPA 1

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

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

Natick Water Department is a public water system drawing on groundwater, based in Natick, Massachusetts, serving about 37,006 people, including Natick, Dover, Wellesley. Under EPA's Fifth Unregulated Contaminant Monitoring Rule it was tested for 29 PFAS and lithium 8 times across 4 sampling points between Dec 2024 and Jun 2025.

Every PFAS detected

PFAS Detected Highest Worst point avg EPA limit
PFOS
Perfluorooctanesulfonic acid		 4 of 8 37.3 ppt 32.2 ppt 4 ppt
PFOA
Perfluorooctanoic acid		 4 of 8 14.3 ppt 12.0 ppt 4 ppt
PFHxS
Perfluorohexanesulfonic acid		 2 of 8 11.2 ppt 7.6 ppt 10 ppt
PFBS
Perfluorobutanesulfonic acid		 4 of 8 6.5 ppt 4.8 ppt none
PFBA
Perfluorobutanoic acid		 1 of 8 5.0 ppt 2.5 ppt none
PFPeA
Perfluoropentanoic acid		 2 of 8 3.5 ppt 1.8 ppt none

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

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

01760 02030 02482

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 Natick Water Department water: EPA UCMR 5 results." Data: U.S. EPA Fifth Unregulated Contaminant Monitoring Rule, final release August 2026, PWSID MA3198000. https://wellandtap.com/pfas/massachusetts/natick-water-department/

About this data

Source: U.S. EPA, UCMR 5 occurrence data, final release August 2026 (PWSID MA3198000). Population: EPA SDWIS. Averages count results below the reporting level as zero, the same convention EPA uses for running annual averages. Full method.