City of Sonoma
EPA ID: CA4910012 · 11,725 people served · 1 ZIP code
ZipCheckup's reading of EPA records for City of Sonoma (CA4910012): 1 violation recorded with unresolved status in the SDWIS data used. City of Sonoma | open status in EPA data: 1 violation | people served: about 11,725.
Data: EPA SDWIS
Service Area Map
Coverage area for City of Sonoma Source: EPA SDWIS service area boundaries.
Service area boundary
Demographics of ZIP Codes Served
The ZIP codes associated with City of Sonoma have a median household income of $108,322 and about 35,139 residents live in those ZIP codes (Census; not the number of people this system supplies). 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 classified in EPA records as a groundwater source. 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
PFAS in ZIP Codes This System Serves
PFAS ("forever chemicals") have been reported in samples from water systems associated with the ZIP codes in this system's area. These results can come from other water systems serving the same ZIP codes; check the UCMR5 section for any results reported for this system. 6 detections recorded. 2 detections are above the level of a federal PFAS MCL (4 ppt for PFOA and PFOS), with compliance required from 2029.
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 | LEAD AND COPPER RULE REVISIONS | Non-health-based | Unaddressed (current) |
| April 1, 2021 | Arsenic | Non-health-based | Resolved |
Contaminants Detected
The following contaminants have been flagged in EPA records for this water system:
| Contaminant | Category | Violations | Health-Based |
|---|---|---|---|
| Arsenic | Monitoring & Reporting | 1 | No |
| LEAD AND COPPER RULE REVISIONS | Monitoring & Reporting | 1 | No |
Lead & Copper
EPA Lead and Copper Rule evidence attributed directly to this water system:
| Lead Level | Exceeds Action Level | Sample Date |
|---|---|---|
| Below the reporting limit | No | 2023-12-31 |
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: Ask your water utility whether running cold water for 2 minutes is enough to flush your plumbing before drinking.
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 available EPA compliance records 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: Sample Above an EPA MCL Value or State Standard
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). One or more PFAS measurements were above the level of the EPA MCL for that compound (April 2024 rule, which takes effect in 2029) or above an applicable state drinking-water standard; a monitoring result above that level is not by itself a violation.
EPA's April 2024 PFAS rule sets MCLs of 4 ppt for PFOA and PFOS and 10 ppt for PFHxS, PFNA and HFPO-DA (GenX); water systems must comply from 2029. Other PFAS compounds have no individual federal MCL. A state standard is shown only where this system's state has its own enforceable PFAS limit. Detection results are EPA UCMR5 samples, not a measurement at your tap.
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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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.