San Joaquin County tap water
6 of 13 water systems serving San Joaquin County with full PFAS testing averaged above a 2024 federal PFAS level at one or more sampling points.
- 92 community water systems list this county as served; 11 serve 3,300+ people with full PFAS testing.
- 16 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 |
|---|---|---|---|---|
| City of Stockton | Surface water | 192,702 | Yes | 2 |
| California Water Service - Stockton | Purchased surface water | 182,775 | No | 0 |
| Tracy, City of | Surface water | 98,215 | No | 0 |
| Manteca, City of | Purchased surface water | 84,928 | Yes | 0 |
| Lodi, City of | Surface water | 67,093 | Yes | 0 |
| City of Lathrop | Purchased surface water | 38,596 | Yes | 0 |
| City of Mountain House | Surface water | 26,400 | No | 0 |
| Ripon, City of | Groundwater | 15,753 | Yes | 0 |
| Escalon, City of | Groundwater | 7,232 | No | 0 |
| San Joaquin County - Lincoln Village | Purchased surface water | 5,841 | No | 0 |
| San Joaquin County-Mokelumne Acres | Groundwater | 3,802 | Yes | 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.