Howell Mountain Mutual Water Company
EPA ID: CA2810001 · 1,240 people served · 5 ZIP codes
Five clean years on EPA record — Howell Mountain Mutual Water Company, 1,240 residents served.
Data: EPA SDWIS Last verified: 2026-04-02
Compliance Trajectory
Stable · Risk tier: High · 85% chance of violation in next 12 months
Violations went from 6 (2021) to 1 (2024). Violation counts have remained relatively steady.
Service Area Map
Coverage area for Howell Mountain Mutual Water Company Source: EPA SDWIS service area boundaries.
Service area boundary — Grade C
Service Area Demographics
The Howell Mountain Mutual Water Company serves a community with a median household income of $116,534 and an estimated 18,668 residents across its service area. Approximately 74% of housing stock was built before 1986, which increases the likelihood of lead service lines and older plumbing.
🌊 Where Does Your Water Come From?
Howell Mountain Mutual Water Company's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 2% of homes in Napa 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. 4 detections recorded. 2 exceed federal EPA limits (4 ppt for PFOA/PFOS). 2 exceed 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
Howell Mountain Mutual Water Company (EPA ID: CA2810001) is a community water system in California that serves approximately 1,240 people from surface water sources.
This system provides water to 5 ZIP codes across 5 communities.
Average Home Safety Score: C (66/100)
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: 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.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Howell Mountain Mutual Water Company (CA2810001) on EPA.gov.
Frequently Asked Questions
Is Howell Mountain Mutual Water Company water safe to drink?
Based on EPA records, Howell Mountain Mutual Water Company has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does Howell Mountain Mutual Water Company serve?
Howell Mountain Mutual Water Company serves approximately 1,240 people across 5 ZIP codes in California.
Where does Howell Mountain Mutual Water Company get its water?
The primary water source is surface water.
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
Howell Mountain Mutual Water Company (EPA ID: CA2810001) — request the latest Consumer Confidence Report or ask about specific contaminants.