San Luis Obispo County tap water
5 of 17 water systems serving San Luis Obispo County with full PFAS testing averaged above a 2024 federal PFAS level at one or more sampling points.
- 69 community water systems list this county as served; 15 serve 3,300+ people with full PFAS testing.
- 17 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 |
|---|---|---|---|---|
| San Luis Obispo Water department | Surface water | 49,534 | No | 0 |
| Atascadero Mutual Water CO | Groundwater | 33,307 | Yes | 0 |
| City of Paso Robles Water Division | Surface water | 31,176 | Yes | 0 |
| City of Arroyo Grande Utilities Division | Purchased surface water | 17,963 | Yes | 0 |
| California Mens Colony | Surface water | 15,000 | No | 0 |
| Nipomo Comm Services Dist | Purchased surface water | 13,771 | No | 0 |
| City of Grover Beach Public Works dept | Surface water | 12,701 | No | 0 |
| Morro Bay Pw dept - Water Division | Purchased surface water | 10,757 | No | 0 |
| Templeton Csd | Groundwater | 8,041 | No | 0 |
| Pismo Beach Water department | Purchased surface water | 7,944 | No | 3 |
| Oceano Comm Services Dist. | Purchased surface water | 7,598 | No | 0 |
| Los Osos Community Services District | Groundwater | 7,086 | 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.