Sonoma Ranch Mutual Water Company
EPA ID: CA4900843 · 151 people served · 14 ZIP codes
Sonoma Ranch Mutual Water Company's five-year compliance history is clean by every EPA metric — no health-based violations, no monitoring lapses, no enforcement actions on record, reflecting consistent performance for a utility that supplies water to approximately 151 residents year after year.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Sonoma Ranch Mutual Water Company Source: EPA SDWIS service area boundaries.
Service area boundary — Grade C
Service Area Demographics
The Sonoma Ranch Mutual Water Company serves a community with a median household income of $108,322 and an estimated 271,867 residents across its service area. Approximately 75% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
💧 Where Does Your Water Come From?
Sonoma Ranch Mutual Water Company'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.
About 1% of homes in Contra Costa County, California rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Infrastructure Risk
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 14 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
Sonoma Ranch Mutual Water Company (EPA ID: CA4900843) is a community water system in California that serves approximately 151 people from groundwater sources.
This system provides water to 14 ZIP codes across 7 communities.
Average Home Safety Score: C (67/100)
Based on water quality violations, lead levels, and radon risk across all ZIP codes served by this system.
Violation History
Lead & Copper
No Lead and Copper Rule sampling data available for this water system.
Radon Risk in Service Area
Dominant radon zone for ZIP codes served by this system: Zone 3 (Low Risk)
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: 1 ZIP code confirmed via EPA Community Water System Service Area Boundaries v3 plus 13 additional ZIPs inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
- 94547 — Hercules
- 94564 — Pinole
- 94572 — Rodeo
- 94801 — Richmond
- 94802 — Richmond
- 94803 — El Sobrante
- 94804 — Richmond
- 94805 — Richmond
- 94806 — San Pablo
- 94807 — Richmond
- 94808 — Richmond
- 94820 — El Sobrante
- 94850 — Richmond
- 95476 — Sonoma
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Sonoma Ranch Mutual Water Company (CA4900843) on EPA.gov.
Frequently Asked Questions
Is Sonoma Ranch Mutual Water Company water safe to drink?
Based on EPA records, Sonoma Ranch Mutual Water Company has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does Sonoma Ranch Mutual Water Company serve?
Sonoma Ranch Mutual Water Company serves approximately 151 people across 14 ZIP codes in California.
Where does Sonoma Ranch Mutual Water Company get its water?
The primary water source is groundwater.
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
This system reports zero confirmed lead service lines in its inventory. Unknown-material counts may still warrant verification.
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
Frequently Asked Questions
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
Sonoma Ranch Mutual Water Company (EPA ID: CA4900843) — request the latest Consumer Confidence Report or ask about specific contaminants.