B68/100
SONOMA, CITY OF — Water Quality Report 2026
Serving 11,725 people · California
Water Source
Groundwater
County
—
System ID
CA4910012
Violations
9
Contaminant Test Results
3 contaminants above EPA health goals
| Contaminant | Detected | Limit (MCL) | Status |
|---|---|---|---|
Copper (90th percentile) | 1.50 mg/L | 1.30 mg/L | Over Limit |
PFOA | 0.006 µg/L | 0.004 µg/L | Over Limit |
vanadium | 24.00 µg/L | — | Above Goal |
EPA Violation History
1
Violation (last 5yr)
1
Unresolved
0
Health-Related
TIER 3Unresolved
Reporting Violation
This is a paperwork/process violation — it does not mean a contaminant was detected at unsafe levels.
Understanding violation severity
Tier 1Urgent health risk. Utility must notify all customers within 24 hours.Tier 2Important health or treatment issue. Customers notified within 30 days.Tier 3Administrative or monitoring issue. Reported in the annual water quality report.
Source: EPA Safe Drinking Water Information System (SDWIS) · Updated quarterly
Frequently Asked Questions About SONOMA, CITY OF
Is SONOMA, CITY OF water safe to drink?
SONOMA, CITY OF water receives a grade of B (68/100), which is considered good. Out of 67 contaminants tested, 2 exceed EPA legal limits. 3 contaminant(s) exceed non-enforceable health goals. The water meets federal safety standards.
What contaminants has SONOMA, CITY OF detected?
67 contaminants were tested in SONOMA, CITY OF's water. Notable contaminants include PFOA, Copper (90th percentile), vanadium. 2 exceed EPA legal limits (MCLs). 3 exceed EPA health goals (MCLGs).
Does SONOMA, CITY OF have any EPA violations?
Yes, SONOMA, CITY OF has 9 EPA violation(s) on record, with the most recent in 2025. Violation types include RPT, MR, MON. 1 are health-based violations.
How many people does SONOMA, CITY OF serve?
SONOMA, CITY OF serves approximately 11,725 people, California. The system provides water to 1 community: Sonoma.
What type of water does SONOMA, CITY OF provide?
SONOMA, CITY OF sources its water from groundwater. Groundwater is pumped from underground aquifers, which often provides natural filtration. The utility's system ID is CA4910012.
How does SONOMA, CITY OF compare to other utilities in California?
SONOMA, CITY OF scores 68/100 with a grade of B (good). This is an above-average performance for utilities statewide. Visit our California state page for a full comparison of water systems.