Diamond a Mutual Water Company
EPA ID: CA4900562 · 640 people served · 1 ZIP code
With a five-year violation-free history, Diamond a Mutual Water Company delivers safe water to 640 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Diamond a Mutual Water Company Source: EPA SDWIS service area boundaries.
Service area boundary
Service Area Demographics
The Diamond a Mutual Water Company 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?
Diamond a 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 Sonoma 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. 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
Diamond a Mutual Water Company (EPA ID: CA4900562) is a community water system in California that serves approximately 640 people from groundwater sources.
This system serves ZIP code 95476 in Sonoma.
Violation History
Lead & Copper
No Lead and Copper Rule sampling data available for this water system.
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 Diamond a Mutual Water Company (CA4900562) on EPA.gov.
Frequently Asked Questions
Is Diamond a Mutual Water Company water safe to drink?
Based on EPA records, Diamond a Mutual Water Company has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does Diamond a Mutual Water Company serve?
Diamond a Mutual Water Company serves approximately 640 people across 1 ZIP code in California.
Where does Diamond a 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.