Sonoma, CA: 1 Health Violation — 73/100 (2026)
1 ZIP code · 9 water systems · Updated 2026-06-03
Across Sonoma, EPA monitoring data shows low violation rates and healthy safety margins — a pattern that places the city well above CA's average for drinking water compliance across recent reporting cycles.
How Sonoma Compares
Data: EPA SDWIS Last verified: 2026-06-03
Sonoma Water: The Quick Version
- Your city's water systems recorded 4 violations in the past 5 years.
- Average lead level: 0.0084 mg/L.
- Homes built before 1986: 69% — older plumbing may contain lead solder.
- Estimated remediation: $2,700 per household.
- CDC health risk index: 11.32.
Water Systems Serving Sonoma
Water delivery in Sonoma, CA is handled by 3 utilities rather than a single system — drawn from 9 providers in federal records, each filing its own compliance reports and setting its own rates.
Overview
We track water quality and home safety data for 1 ZIP code in Sonoma, California (population ~35,139), covering 9 community water systems serving approximately 182,197 people region-wide.
1 of 1 ZIP code (100%) have recorded EPA violations. 1 health-based violation documented.
Home Safety Score
Average Home Safety Score for Sonoma: B (73/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
Sonoma water systems draw from: Groundwater.
Lead & Copper
- Average lead level (90th percentile): 0.0084 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Stage 2 DBP Rule | Treatment Technique | 6 | 1 |
| Barium | Inorganic | 2 | 1 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 95476 | B | 4 | 1 | City of Sonoma, |
All ZIP Codes in Sonoma
- 95476 [B] — 4 violations ⚠
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
CDC Health Data for Sonoma
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Key Contaminants Detected in Sonoma
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
How Old Is Sonoma's Housing Stock?
With 69% of homes built before 1986, lead solder in plumbing is a potential concern. The EPA banned lead solder in 1986, but many older homes retain original plumbing.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
When more than half a city's housing predates the 1986 federal ban on lead solder, plumbing-era lead risk becomes a citywide concern rather than an exception. Sonoma's median build year of 1973 places it squarely in that category.
Over half of homes in Sonoma were built before 1986, when lead solder was banned. Older plumbing may leach lead into drinking water, especially with corrosive water chemistry.
Source: U.S. Census Bureau ACS B25034.
Sonoma: Remediation Cost in Perspective
For most homeowners in Sonoma, the estimated cost of water and safety remediation represents a proportionally modest share of what properties are worth — placing this area in the lower tier of the remediation share scale.
Remediation costs in Sonoma are relatively low compared to home values. The $1,750–$3,900 estimated range is a small fraction of median property value. Home values are 19% above the California average.
Protecting Children from Lead in Sonoma
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
Older stock in Sonoma represents 69% of the inventory, and citywide monitoring runs at or above the federal action level — making an in-home read a standard household-level step.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Climate-Related Water Risk for Sonoma
Measured across the NFIP's multi-decade tracking period, Sonoma shows a moderate flood record — 93 claims and 100% of ZIP codes carrying FEMA flood zone status. For water quality, that combination matters because flood events at this frequency can periodically stress infrastructure: treatment plants, private wells, and distribution systems all face elevated risk during significant flooding.
Sonoma has a moderate flood history with 93 FEMA claims averaging $24,828 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$2,700</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
Deep Dive Reports
Detailed analysis for Sonoma, CA