San Quentin, CA Water Safety: 66/100 (2026)
2 ZIP codes · 1 water system · Updated 2026-06-03
San Quentin, CA: mid-range safety grade, uneven compliance across service areas.
How San Quentin Compares
Data: EPA SDWIS Last verified: 2026-06-03
Water Systems Serving San Quentin
Consolidated water delivery characterizes San Quentin, CA: among 1 system in federal records, one utility holds the dominant service position — carrying the rate-setting authority, the infrastructure obligations, and the EPA reporting burden for most residential addresses.
Overview
We track water quality and home safety data for 2 ZIP codes in San Quentin, California (population ~2,115), covering 1 community water system serving approximately 186,895 people region-wide.
No EPA violations recorded across any ZIP codes in San Quentin — an excellent indicator of water quality.
Home Safety Score
Average Home Safety Score for San Quentin: C (66/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
San Quentin water systems draw from: Surface water.
Lead & Copper
- Lead data: not yet available for San Quentin
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 3 (Low Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 0 ZIP codes
- Zone 3 (Low): 2 ZIP codes
Areas with No Violations
| ZIP Code | Safety Score | System | Population |
|---|---|---|---|
| 94964 | C | MARIN MUNICIPAL WATER DISTRICT | 186,895 |
| 94974 | C | MARIN MUNICIPAL WATER DISTRICT | 186,895 |
All ZIP Codes in San Quentin
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.
CDC Health Data for San Quentin
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
What You Can Do in San Quentin
- Test your water at home. City-level data shows averages — your tap may differ. NSF-certified test kits cost $20-40 and give results in days.
- Install a certified water filter. An NSF-certified pitcher or under-sink filter removes most common contaminants.
- Check your home's plumbing. Homes built before 1986 may have lead solder in pipes. A licensed plumber can assess your risk.
Deep Dive Reports
Detailed analysis for San Quentin, CA