Neighborhood Report
Grade C
San Mateo, CA Neighborhood Water Quality — Grade C
5 ZIP codes · 20 EPA violations
Data source: EPA SDWIS Last verified: 2026-06-04
Water quality varies significantly across San Mateo, CA. We analyzed 5 ZIP codes to help you compare neighborhoods by water safety, lead risk, and EPA compliance.
City Overview: Grade C (66/100)
| Grade | Neighborhoods | % |
|---|---|---|
| A | 0 | 0% |
| B | 0 | 0% |
| C | 5 | 100% |
| D | 0 | 0% |
| F | 0 | 0% |
Neighborhood Rankings
Every ZIP code in San Mateo ranked by Home Safety Score:
| Rank | ZIP Code | Score | Grade | Violations | Lead Risk |
|---|---|---|---|---|---|
| 1 | 94497 | 68 | C | 4 | 0.0017 mg/L |
| 2 | 94401 | 66 | C | 4 | 0.0017 mg/L |
| 3 | 94402 | 66 | C | 4 | 0.0017 mg/L |
| 4 | 94403 | 66 | C | 4 | 0.0017 mg/L |
| 5 | 94404 | 66 | C | 4 | 0.0017 mg/L |
How Neighborhoods Compare
Each ZIP code compared to county and state averages:
- 0 neighborhoods score better than county average
- 5 neighborhoods score worse than county average
EPA Violations
- 20 total violations across San Mateo
- 15 health-based violations
- 5 of 5 ZIP codes have violations
- 0 ZIP codes exceed EPA lead action level
Top Contaminants
| Contaminant | Violations | ZIPs |
|---|---|---|
| Lead | 10 | 5 |
| Stage 2 DBP Rule | 10 | 5 |
Frequently Asked Questions
What is the safest neighborhood in San Mateo?
ZIP code 94497 has the highest safety score in San Mateo at 68/100 (grade C). Check the full report for details.
Is San Mateo water safe to drink?
San Mateo has an average water safety score of 66/100 (C). Water quality varies by neighborhood — no ZIP codes currently exceed EPA lead limits. Always check your specific ZIP code.
Related Pages
Data Sources
- EPA SDWIS
- U.S. Census Bureau
Updated daily.