California — 4th District
119th Congress · 127 ZIP codes · Avg score 77/100 · Grade B · Updated 2026-06-03
Data: EPA SDWIS / Census 119th Congress Last verified: 2026-06-03
Top Contaminants
ZIP Codes in This District
100 ZIP codes tracked in California's 4th District. Showing top 50 by safety score.
| # | ZIP Code | City | Safety Score | Grade | Violations |
|---|---|---|---|---|---|
| 1 | 94083 | South San Francisco | 99 | A | 0 |
| 2 | 94592 | Vallejo | 99 | A | 0 |
| 3 | 95444 | Graton | 99 | A | 0 |
| 4 | 95406 | Santa Rosa | 98 | A | 2 |
| 5 | 95433 | El Verano | 97 | A | 0 |
| 6 | 94931 | Cotati | 95 | A | 0 |
| 7 | 95439 | Fulton | 95 | A | 0 |
| 8 | 94955 | Petaluma | 94 | A | 2 (1 health) |
| 9 | 94975 | Petaluma | 94 | A | 2 (1 health) |
| 10 | 94999 | Petaluma | 94 | A | 2 (1 health) |
| 11 | 95402 | Santa Rosa | 94 | A | 2 |
| 12 | 95409 | Santa Rosa | 94 | A | 2 |
| 13 | 94951 | Penngrove | 92 | A | 4 |
| 14 | 94953 | Petaluma | 91 | A | 2 (1 health) |
| 15 | 94510 | Benicia | 90 | A | 0 |
| 16 | 94589 | Vallejo | 90 | A | 0 |
| 17 | 94591 | Vallejo | 90 | A | 0 |
| 18 | 95452 | Kenwood | 90 | A | 0 |
| 19 | 94922 | Bodega | 89 | A | 0 |
| 20 | 95403 | Santa Rosa | 89 | A | 2 |
| 21 | 95404 | Santa Rosa | 89 | A | 2 |
| 22 | 95405 | Santa Rosa | 89 | A | 2 |
| 23 | 95407 | Santa Rosa | 89 | A | 2 |
| 24 | 95419 | Camp Meeker | 89 | A | 0 |
| 25 | 95426 | Cobb | 89 | A | 4 (2 health) |
| 26 | 95457 | Lower Lake | 89 | A | 2 |
| 27 | 95425 | Cloverdale | 88 | A | 1 |
| 28 | 95441 | Geyserville | 88 | A | 1 |
| 29 | 95625 | Elmira | 88 | A | 0 |
| 30 | 94503 | American Canyon | 87 | A | 0 |
| 31 | 94923 | Bodega Bay | 87 | A | 0 |
| 32 | 94954 | Petaluma | 86 | A | 2 (1 health) |
| 33 | 95461 | Middletown | 86 | A | 2 (1 health) |
| 34 | 95465 | Occidental | 86 | A | 6 |
| 35 | 94080 | South San Francisco | 85 | A | 0 |
| 36 | 94571 | Rio Vista | 85 | A | 0 |
| 37 | 94590 | Vallejo | 85 | A | 0 |
| 38 | 94497 | San Mateo | 84 | B | 4 (3 health) |
| 39 | 95401 | Santa Rosa | 84 | B | 2 |
| 40 | 94547 | Hercules | 83 | B | 4 (2 health) |
| 41 | 95421 | Cazadero | 83 | B | 4 |
| 42 | 95442 | Glen Ellen | 82 | B | 0 |
| 43 | 95467 | Hidden Valley Lake | 82 | B | 0 |
| 44 | 95492 | Windsor | 82 | B | 0 |
| 45 | 95620 | Dixon | 82 | B | 0 |
| 46 | 92602 | Irvine | 81 | B | 19 |
| 47 | 92603 | Irvine | 81 | B | 19 |
| 48 | 92606 | Irvine | 81 | B | 19 |
| 49 | 92614 | Irvine | 81 | B | 19 |
| 50 | 92616 | Irvine | 81 | B | 19 |
Overview
California's 4th District serving an estimated 10,942,678 residents encompasses 127 ZIP codes tracked by ZipCheckup. The district's average Home Safety Score is B (77/100).
519 EPA violations have been recorded across this district's water systems. 142 are health-based violations. About 43% of tracked ZIP codes have at least one violation.
Top Contaminants
The most frequently cited water quality issues in this district:
- Total Trihalomethanes (TTHM) — 157 violations
- Haloacetic Acids (HAA5) — 146 violations
- Consumer Confidence Report Rule — 61 violations
- Stage 2 DBP Rule — 51 violations
- Lead — 46 violations
Housing Context
Homes in this district were built on average around 1973 (~53 years old). Older homes may have lead pipes or solder — consider a water filter if your home predates 1986.
Lead Alert: 5 ZIP codes in this district exceed the EPA action level for lead. Consider using a certified lead-removal filter.
Data Sources
- Water quality violations: EPA Safe Drinking Water Information System (SDWIS)
- Congressional district boundaries: U.S. Census Bureau, 119th Congress
- Housing age: U.S. Census Bureau American Community Survey
Updated daily. Data covers 127 ZIP codes in California's 4th District.