Barnstable County tap water
2 of 20 water systems serving Barnstable County with full PFAS testing averaged above a 2024 federal PFAS level at one or more sampling points.
- 30 community water systems list this county as served; 20 serve 3,300+ people with full PFAS testing.
- 1 had a health-based violation since 2021-10-26.
Largest systems serving this county
| System | Source | People served (whole system) | PFAS above a 2024 level? | Violations since 2021-10-26 |
|---|---|---|---|---|
| Falmouth Water dept | Surface water | 97,551 | No | 0 |
| Dennis Water District | Groundwater | 65,000 | No | 0 |
| Upper Cape Regional Water Cooperative | Groundwater | 56,250 | No | 0 |
| Centerville Osterville Marstons Mills Wd | Groundwater | 50,000 | Yes | 0 |
| Harwich Water department | Groundwater | 39,144 | No | 0 |
| Yarmouth Water department | Groundwater | 38,900 | No | 0 |
| Mashpee Water District | Groundwater | 36,922 | No | 0 |
| Brewster Water department | Groundwater | 35,000 | No | 0 |
| Hyannis Water System, Town of Barnstable | Groundwater | 35,000 | No | 0 |
| Chatham Water department | Groundwater | 30,000 | No | 0 |
| Sandwich Water District | Groundwater | 23,000 | No | 0 |
| Bourne Water District | Groundwater | 22,500 | No | 0 |
Which one is yours? A county usually has several utilities. Your bill or your utility's annual water-quality report names yours. Population is for the whole system, which can cross county lines.
Not medical or legal advice. UCMR 5 results are screening data, not compliance determinations.
Sources and freshness
Public-water-system facts, violations and lead/copper results: EPA ECHO SDWA download (SDWIS snapshot 2026-10-13). PFAS and lithium results: EPA UCMR 5 final data (sampling 2023–2025). Both are U.S. government works, downloaded 2026-10-26. Numbers are computed by the published method; the same fields are in the open data files.