City of Sonoma
EPA ID: CA4910012 · 11,725 people served · 1 ZIP code
ZipCheckup's reading of EPA SDWIS for City of Sonoma (CA4910012): 1 unresolved EPA violation on record. 1 open EPA finding remain on record at City of Sonoma - the utility supplies approximately 11,725 people.
Data: EPA SDWIS
Service Area Map
Coverage area for City of Sonoma Source: EPA SDWIS service area boundaries.
Service area boundary
Service Area Demographics
The City of Sonoma serves a community with a median household income of $108,322 and an estimated 35,139 residents across its service area. Approximately 69% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
City of Sonoma's water is pumped from underground aquifers. Groundwater is naturally filtered through rock and soil, but it can be vulnerable to PFAS contamination, nitrates from agriculture, and industrial chemicals that seep into the water table.
Infrastructure Risk
Detected Contaminants
How City of Sonoma compares to EPA limits
What This Means For You
Stage 2 DBP Rule at 1 mg/L exceeds the EPA maximum of mg/L.
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 6 detections recorded. 2 exceed federal EPA limits (4 ppt for PFOA/PFOS). 1 exceeds state limits.
Comparable Water Systems
Similar-sized systems in California
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
City of Sonoma, (EPA ID: CA4910012) is a community water system in California that serves approximately 11,725 people from groundwater sources.
This system serves ZIP code 95476 in Sonoma.
Violation History
Status breakdown for accepted records with record years 2021-2026: 1 resolved, 0 archived, 0 addressed, and 1 unaddressed. Under this source contract, current noncompliance is the sum of addressed and unaddressed records. Archived and resolved records are excluded from current noncompliance.
Recent Violations
| Date | Contaminant | Type | Status |
|---|---|---|---|
| July 2, 2025 | Stage 2 DBP Rule | Non-health-based | Unaddressed (current) |
| April 1, 2021 | Barium | Non-health-based | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Barium | Inorganic | 1 | No |
| Stage 2 DBP Rule | Treatment Failure | 1 | No |
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| 0 mg/L | No | N/A |
No copper action-level exceedance record appears for this PWSID in the accepted LCR snapshot. This does not establish a clean copper measurement.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: Service area ZIP codes sourced from EPA Community Water System Service Area Boundaries v3 (March 2026 release). These ZIPs reflect the actual deployment footprint recorded by CA or modeled from parcel and building-footprint data.
- 95476 - Sonoma
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for City of Sonoma (CA4910012) on EPA.gov.
Frequently Asked Questions
Is City of Sonoma water safe to drink?
The accepted 2026Q2 ECHO snapshot shows 1 current noncompliance record and zero current records classified as health-based. That classification is not a property-specific water test or safety guarantee.
How many people does City of Sonoma serve?
City of Sonoma serves approximately 11,725 people across 1 ZIP code in California.
Where does City of Sonoma get its water?
The primary water source is groundwater.
Federal UCMR5 PFAS Monitoring: Detected
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). PFAS compounds were detected below the current state-enforceable MCL.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Frequently Asked Questions
How to cite this page
ZipCheckup. (n.d.). City of Sonoma (CA): 2 EPA Violations. https://zipcheckup.com/water-system/ca4910012/
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author = {{ZipCheckup}},
title = {{City of Sonoma (CA): 2 EPA Violations}},
year = {n.d.},
url = {https://zipcheckup.com/water-system/ca4910012/}
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What You Can Do
Test your water
Home test kits can detect lead, bacteria, and other contaminants at your tap. Find the right filter →
Check your specific ZIP code
Water quality can vary within a system. View nearest ZIP report →
Contact your utility
City of Sonoma (EPA ID: CA4910012) - request the latest Consumer Confidence Report or ask about specific contaminants.