County · California
Santa Clara County, California: drinking water records
This overview covers 58 ZIP codes and 76 community water systems in Santa Clara County. It also stands in for 0 ZIP codes whose utility has too little EPA data for a page of its own.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems with the most complete records
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| San Jose Water CA4310011 | 1,039,920 | 1,125 | 2 | 1 | 0 ppb |
| City of Gilroy CA4310004 | 59,203 | 420 | 7 | 1 | 2 ppb |
| Stanford University CA4310013 | 35,853 | 120 | 0 | 1 | 0 ppb |
| City of Sunnyvale CA4310014 | 157,566 | 600 | 0 | 0 | 0 ppb |
| City of Santa Clara CA4310012 | 130,746 | 1,190 | 0 | 0 | 2.7 ppb |
| Great Oaks Wc INC CA4310022 | 110,088 | 1,140 | 4 | 0 | 0 ppb |
| City of San Jose - Evg/Edv/Coy CA4310020 | 101,265 | 275 | 0 | 0 | 0 ppb |
| City of Milpitas CA4310005 | 81,773 | 240 | 0 | 0 | 2.5 ppb |
| City of Mountain View CA4310007 | 81,501 | 430 | 0 | 0 | 0 ppb |
| Cwsc Los Altos Suburban CA4310001 | 69,973 | 1,080 | 1 | 0 | 1.5 ppb |
| City of Palo Alto CA4310009 | 67,231 | 120 | 0 | 0 | 0 ppb |
| City of Morgan Hill CA4310006 | 47,374 | 960 | 3 | 0 | 0 ppb |
| City of San Jose - Nsj/Alviso CA4310019 | 45,559 | 215 | 0 | 0 | 0 ppb |
| City of Cupertino CA4310018 | 16,336 | 155 | 0 | 0 | 0 ppb |
| Nasa Ames Research Center CA4300997 | 16,273 | 120 | 0 | 0 | 10.4 ppb |
| Purissima Hills Water District CA4310021 | 6,245 | 120 | 0 | 0 | 6 ppb |
| Cal Am - West San Martin CA4300543 | 1,173 | 0 | 0 | 1 | 3 ppb |
| Coyote Valley RV Resort CA4300994 | 500 | 0 | 0 | 1 | 4.6 ppb |
| Chemeketa Park Mutual Water Company CA4300517 | 346 | 0 | 0 | 1 | 18.2 ppb |
| Twin Valley INC CA4300575 | 317 | 0 | 0 | 54 | 3.9 ppb |
| Lupin Lodge CA4300716 | 300 | 0 | 0 | 3 | 0.2 ppb |
| Casa de Fruta Water System CA4300611 | 250 | 0 | 0 | 1 | 0 ppb |
| Mt. Eden Mutual Water Company CA4300831 | 165 | 0 | 0 | 1 | 0 ppb |
| Lake Canyon Mutual Water Company CA4300522 | 156 | 0 | 0 | 1 | 6 ppb |
| Roseview Heights Mutual Water Company CA4300562 | 148 | 0 | 0 | 1 | 0 ppb |
ZIP reports in Santa Clara County
No ZIP report in this county is published yet.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.