Water Quality in Sonoma, CA: 9 Violations - Grade N/A
5 water systems · 1 directly mapped ZIP records
Available EPA records report 9 violations across 1 directly mapped ZIP records with known counts for Sonoma. This is compliance evidence, not a property-level tap-water verdict.
Data: EPA Safe Drinking Water Information System (SDWIS)
Water Quality by ZIP Code in Sonoma
This table shows typed EPA water evidence only. Missing violation counts are displayed as N/A, not zero.
| ZIP Code | Violations | Health | |
|---|---|---|---|
| 95476 | 9 | 3 | View report → |
Water Quality Overview
Sonoma, California has directly mapped EPA water-system data for 1 ZIP codes. This page reports typed compliance facts and does not relabel the multi-source Home Safety Score as a drinking-water grade.
The available EPA records report 9 violations, including 3 health-based violations across 1 directly mapped ZIP record with reported counts.
Lead Levels
The average 90th percentile lead level across Sonoma water systems is 0.0027 mg/L - within EPA limits. No exceedances appear among the 1 ZIP records with known lead status.
With 69% of homes built before 1986, Sonoma has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Water Systems Serving Sonoma
Sonoma is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 35,139 people across 1 ZIP code.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 10 enforcement actions against water systems serving Sonoma. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Sonoma
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels and violation history
Request your CCR - your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test - certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration - NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories - monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Sonoma Water Systems
The following contaminants have been detected or caused violations across Sonoma's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Stage 2 DBP Rule | Treatment Technique | N/A | 7 | 1 | Yes |
| Barium | Inorganic | 2 mg/L | 1 | 1 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 10 enforcement actions against water systems serving Sonoma. Recent actions:
| Date | Action Type |
|---|---|
| 2024-09-19 | State Order Extension |
| 2023-06-19 | State Order Extension |
| 2022-03-23 | State Filed Suit |
| 2021-09-08 | State Filed Suit |
| 2021-07-22 | State Order Extension |
| 2021-06-29 | State Filed Suit |
| 2021-06-17 | State Order Extension |
| 2021-04-21 | State Filed Suit |
| 2021-03-24 | State Filed Suit |
| 2021-03-24 | State Filed Judgment |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2024-09-19.
Sonoma vs. Nearby California Cities
How Sonoma's water quality compares to similar cities in California:
| City | Direct EPA ZIPs | Violations | Systems | Population |
|---|---|---|---|---|
| Sonoma | 1 | 9 | 5 | 35,139 |
| Temple City | 1 | 0 | 5 | 35,136 |
| Oakdale | 1 | 3 | 5 | 35,024 |
| Ladera Ranch | 1 | 1 | 2 | 35,019 |
Common Questions About Sonoma Water
These are the most common questions residents search for about water quality in Sonoma, California:
Is Sonoma water hard or soft? Water hardness varies by source. Sonoma's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Sonoma tap water? City-level EPA records cannot determine safety at a specific tap. The measured subset contains 3 health-based violations; check the affected utility record and consider certified testing.
What is the best water filter for Sonoma? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Sonoma vs. California Average
Understanding how Sonoma compares to the broader California average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below - water quality can vary significantly even within Sonoma.
ZIP Codes in Sonoma
Sonoma spans 1 ZIP code. EPA water-system coverage is available for 1 directly mapped ZIP code. Check each ZIP code for detailed contaminant data, violation history, and system information.
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
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Source reporting periods vary. See each cited source for its publication schedule.