County · California
Sonoma County, California: drinking water records
This overview covers 38 ZIP codes and 134 community water systems in Sonoma County. It also stands in for 3 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 |
|---|---|---|---|---|---|
| Sonoma State University CA4910027 | 10,986 | 56 | 0 | 1 | 0 ppb |
| Sea Ranch Water Company,the (Puc) CA4910007 | 1,160 | 180 | 1 | 1 | 0 ppb |
| Santa Rosa, City of CA4910009 | 175,396 | 120 | 0 | 0 | 1.3 ppb |
| Petaluma, City of CA4910006 | 60,781 | 60 | 0 | 0 | 0 ppb |
| Rohnert Park, City of CA4910014 | 43,821 | 480 | 3 | 0 | 0 ppb |
| Windsor, Town of CA4910017 | 25,561 | 120 | 0 | 0 | 0 ppb |
| Valley of the Moon Water District CA4910013 | 23,107 | 415 | 6 | 0 | 0 ppb |
| Sonoma, City of CA4910012 | 11,725 | 360 | 2 | 0 | 0 ppb |
| Healdsburg, City of CA4910005 | 10,985 | 300 | 3 | 0 | 0 ppb |
| Cloverdale, City of CA4910002 | 10,398 | 120 | 0 | 0 | 0 ppb |
| California-American Larkfield (Puc) CA4910023 | 7,913 | 120 | 0 | 0 | 6 ppb |
| Sebastopol, City of CA4910011 | 7,522 | 240 | 0 | 0 | 0 ppb |
| Cotati, City of CA4910016 | 7,303 | 300 | 0 | 0 | 0 ppb |
| Sweetwater Springs Cwd - Guerneville CA4910004 | 6,000 | 60 | 0 | 0 | 0 ppb |
| Russian River County Water District CA4910008 | 4,150 | 60 | 0 | 0 | 0 ppb |
| California-American Geyserville (Puc) CA4910024 | 1,046 | 120 | 0 | 0 | 0 ppb |
| Diamond a Mutual Water Company CA4900562 | 640 | 0 | 0 | 1 | 0 ppb |
| Cazadero Water Company, INC. (Puc) CA4900508 | 525 | 0 | 0 | 6 | 0 ppb |
| U.S. Coast Guard Training Center CA4910701 | 469 | 0 | 0 | 1 | 0 ppb |
| Rincon Valley Mobile Estates CA4900600 | 460 | 0 | 0 | 1 | 0 ppb |
| Sonoma County Csa 41-Jenner CA4900532 | 406 | 0 | 0 | 11 | 2.7 ppb |
| Branger Mutual Water Company, INC. CA4900545 | 300 | 0 | 0 | 2 | 3.3 ppb |
| Timber Cove County Water District CA4900584 | 271 | 0 | 0 | 1 | 0 ppb |
| Magic Mountain Mutual Water Company CA4900637 | 221 | 0 | 0 | 1 | 6 ppb |
| Mobile Home Estates CA4900720 | 210 | 0 | 0 | 1 | 0 ppb |
ZIP reports in Sonoma County
No ZIP report in this county is published yet.
These ZIP codes are covered by this overview because their utility has too little EPA data for a separate page: 95412, 95431, 95480.
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.