PFAS in tap water, Barnstable County, Massachusetts
4 of 20 water systems had PFAS-4 above our 0.5 ng/L benchmark at the latest sample. Highest: Bourne Water District, 12.4 ng/L. 3 had PFOA or PFOS above the 4 ng/L federal MCL in at least one sample.
20 community water systems · 603,882 people served · newest sample December 29, 2025
Water systems in Barnstable County
| Water system | People served | PFAS-4 at the latest sample | Entry points | Latest sample |
|---|---|---|---|---|
| Falmouth Water Dept | 97,551 | below the 3 to 4 ng/L reporting limit | 4 | November 18, 2024 |
| Dennis Water District | 65,000 | below the 3 to 4 ng/L reporting limit | 9 | April 9, 2024 |
| Upper Cape Regional Water Cooperative | 56,250 | below the 3 to 4 ng/L reporting limit | 3 | December 29, 2025 |
| Centerville Osterville Marstons Mills WD | 50,000 | 4.8 ng/L above the 2029 federal MCL | 15 | October 1, 2025 |
| Harwich Water Department | 39,144 | below the 3 to 4 ng/L reporting limit | 5 | June 26, 2025 |
| Yarmouth Water Department | 38,900 | 3.1 ng/L | 15 | July 29, 2025 |
| Mashpee Water District | 36,922 | below the 3 to 4 ng/L reporting limit | 6 | December 12, 2024 |
| Hyannis Water System, Town of Barnstable | 35,000 | below the 3 to 4 ng/L reporting limit | 3 | April 9, 2024 |
| Brewster Water Department | 35,000 | below the 3 to 4 ng/L reporting limit | 5 | September 17, 2024 |
| Chatham Water Department | 30,000 | below the 3 to 4 ng/L reporting limit | 5 | January 13, 2025 |
| Sandwich Water District | 23,000 | below the 3 to 4 ng/L reporting limit | 10 | February 5, 2025 |
| Bourne Water District | 22,500 | 12.4 ng/L above the 2029 federal MCL | 7 | April 14, 2025 |
| Provincetown Water Department | 22,250 | below the 3 to 4 ng/L reporting limit | 2 | April 10, 2024 |
| Orleans Water Department | 17,460 | below the 3 to 4 ng/L reporting limit | 2 | February 12, 2025 |
| Buzzards Bay Water District | 7,700 | below the 3 to 4 ng/L reporting limit | 5 | July 24, 2023 |
| Town of Eastham | 6,199 | below the 3 to 4 ng/L reporting limit | 2 | October 7, 2025 |
| Otis Air National Guard Base | 6,000 | below the 3 to 4 ng/L reporting limit | 1 | August 8, 2023 |
| Barnstable Fire District | 5,400 | 4.9 ng/L above the 2029 federal MCL | 3 | October 17, 2023 |
| Cotuit Fire District Water Department | 4,938 | below the 3 to 4 ng/L reporting limit | 5 | September 19, 2023 |
| North Sagamore Water District | 4,668 | below the 3 to 4 ng/L reporting limit | 2 | July 11, 2023 |
Not sure which one is yours? The systems report their own service areas to EPA. Check your water bill or your utility's Consumer Confidence Report.
Cities and towns
ZIP codes in Barnstable County
Census ZIP code tabulation areas that overlap the county. A ZIP served by one system opens that system's page; a ZIP shared by several systems lists them.
How to read these numbers
We compare PFAS-4 (PFOA + PFOS + PFNA + PFHxS) with this site's 0.5 ng/L benchmark, the same line as on the European pages. UCMR 5 reporting limits are 3 to 4 ng/L. So any quantified PFAS-4 compound is above the benchmark, and a clean result reads "below the 3 to 4 ng/L reporting limit", never zero. The US legal limit is the 4 ng/L federal MCL for PFOA and PFOS, which systems must meet from April 26, 2029 ("above the 2029 federal MCL").
EPA: "UCMR 5 results do not indicate compliance or noncompliance with the PFAS drinking water standards". Samples are taken where water enters the distribution system, not at your tap. A system may have changed sources or added treatment since. Source: U.S. Environmental Protection Agency (EPA), Office of Water, PFAS National Primary Drinking Water Regulation (NPDWR). Regulation details retrieved September 19, 2026. Every system page tracks the 2029 compliance date and the proposed rescission of the PFHxS, PFNA, HFPO-DA and Hazard Index limits.
This site is a data project, not an official source. If in doubt, check with your water supplier or local authority.