Neighborhood Report
Grade C
San Marcos, CA Neighborhood Water Quality — Grade C
4 ZIP codes · 112 EPA violations
Data source: EPA SDWIS Last verified: 2026-06-04
Water quality varies significantly across San Marcos, CA. We analyzed 4 ZIP codes to help you compare neighborhoods by water safety, lead risk, and EPA compliance.
City Overview: Grade C (69/100)
| Grade | Neighborhoods | % |
|---|---|---|
| A | 0 | 0% |
| B | 1 | 25% |
| C | 3 | 75% |
| D | 0 | 0% |
| F | 0 | 0% |
Neighborhood Rankings
Every ZIP code in San Marcos ranked by Home Safety Score:
| Rank | ZIP Code | Score | Grade | Violations | Lead Risk |
|---|---|---|---|---|---|
| 1 | 92078 | 71 | B | 28 | 0.0011 mg/L |
| 2 | 92079 | 69 | C | 28 | 0.0011 mg/L |
| 3 | 92096 | 69 | C | 28 | 0.0011 mg/L |
| 4 | 92069 | 66 | C | 28 | 0.0011 mg/L |
How Neighborhoods Compare
Each ZIP code compared to county and state averages:
- 0 neighborhoods score better than county average
- 4 neighborhoods score worse than county average
EPA Violations
- 112 total violations across San Marcos
- 24 health-based violations
- 4 of 4 ZIP codes have violations
- 0 ZIP codes exceed EPA lead action level
Top Contaminants
| Contaminant | Violations | ZIPs |
|---|---|---|
| Nickel | 96 | 4 |
| Lead | 8 | 4 |
| Stage 1 DBP Rule | 4 | 4 |
| Stage 2 DBP Rule | 4 | 4 |
Frequently Asked Questions
What is the safest neighborhood in San Marcos?
ZIP code 92078 has the highest safety score in San Marcos at 71/100 (grade B). Check the full report for details.
Is San Marcos water safe to drink?
San Marcos has an average water safety score of 69/100 (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.