Stanislaus County tap water
2 of 12 water systems serving Stanislaus County with full PFAS testing averaged above a 2024 federal PFAS level at one or more sampling points.
- 58 community water systems list this county as served; 12 serve 3,300+ people with full PFAS testing.
- 13 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 |
|---|---|---|---|---|
| Modesto, City of | Purchased surface water | 218,915 | Yes | 0 |
| Turlock, City of | Purchased surface water | 72,888 | No | 0 |
| Ceres, City of | Purchased surface water | 54,513 | Yes | 1 |
| Riverbank, City of | Groundwater | 25,625 | No | 1 |
| Patterson, City of | Groundwater | 24,977 | No | 0 |
| Oakdale, City of | Groundwater | 23,235 | No | 1 |
| City of Modesto - Salida | Purchased surface water | 14,576 | No | 0 |
| City of Newman-Water department | Groundwater | 12,389 | No | 1 |
| City of Waterford | Groundwater | 8,788 | No | 0 |
| Hughson, City of | Groundwater | 7,977 | No | 19 |
| Keyes Community Services Dist. | Groundwater | 5,672 | No | 0 |
| Denair Community Services District | Groundwater | 5,093 | 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.