San Joaquin County, California
55 ZIP codes · Avg score 78/100 · Grade B · Updated 2026-06-04
Although county size varies, San Joaquin County's 55 ZIP codes share reliably safe tap water records and above-average compliance scores.
How San Joaquin County Compares
How San Joaquin County Compares
San Joaquin County scores 5 points above the California state average (73/100) and 10 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
ZIP Code Risk Map
Water Quality Map: San Joaquin County, California
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 11.2 (asthma 9.5%, diabetes 11.9%)
Estimated additional annual cost per homeowner: $2,040, driven primarily by sea_level
Infrastructure: 0.348% avg pipe failure probability, 26% of ZIPs at high risk
60.4% of homes built before 1978 (lead paint era)
Violation History (2021–2025)
↓ Improving trendEPA violation counts by year across San Joaquin County water systems. Health-based shown in red, total in blue.
Peak year: 2023 with 86 violations. Past 5 years: 133 total (133 health-based). Health-based violations are declining versus the prior 2-year window.
Source: EPA SDWIS historical violations. Data may lag 6–12 months for the most recent year.
County Health Indicators vs National Average
Black markers indicate national averages. Source: CDC PLACES, Census ACS.
Infrastructure Overview
Sources: Census ACS (housing age), EPA SDWIS (infrastructure risk model), state bridge inspection data.
Compound Risk Breakdown
Estimated additional annual cost per homeowner: $2,040
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
299,034 housing units in San Joaquin County
Source: U.S. Census Bureau ACS B25034 (Year Structure Built).
Water Safety Affordability
How much it costs to fix water issues relative to home values in San Joaquin County
Remediation costs are relatively manageable for most homeowners in San Joaquin County, representing a small fraction of property value.
Remediation includes water filtration, lead abatement, radon mitigation, and flood protection where applicable. Source: Census ACS, EPA SDWIS.
Health Outcomes vs National Average
CDC PLACES data for San Joaquin County residents
Black markers = national averages. Red = above national avg. Green = below. Source: CDC PLACES, Census ACS.
Water Systems with Most Violations
Top 5 systems in San Joaquin County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | San Joaquin County-mokelumne Acres | 3,802 | 201 |
| 2 | City of Stockton | 191,302 | 198 |
| 3 | San Joaquin County - Lincoln Village | 5,990 | 180 |
| 4 | Cdcr California Health Care Facility | 5,551 | 180 |
| 5 | San Joaquin County - Colonial Heights | 1,841 | 180 |
51 total water systems serve San Joaquin County.
All ZIP Codes in San Joaquin County
55 ZIP codes tracked in San Joaquin County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 95230 | Farmington | 99 | A | 0 | $611K |
| 2 | 95241 | Lodi | 98 | A | 2 (1 health) | — |
| 3 | 95378 | Tracy | 98 | A | 2 (1 health) | — |
| 4 | 95391 | Tracy | 98 | A | 2 (1 health) | $860K |
| 5 | 95258 | Woodbridge | 95 | A | 0 | $554K |
| 6 | 95320 | Escalon | 95 | A | 0 | $490K |
| 7 | 95242 | Lodi | 94 | A | 2 (1 health) | $550K |
| 8 | 95377 | Tracy | 94 | A | 2 (1 health) | $774K |
| 9 | 95330 | Lathrop | 90 | A | 0 | $605K |
| 10 | 95240 | Lodi | 89 | A | 2 (1 health) | $444K |
| 11 | 95376 | Tracy | 89 | A | 2 (1 health) | $588K |
| 12 | 95237 | Lockeford | 88 | A | 0 | $423K |
| 13 | 95366 | Ripon | 88 | A | 0 | $673K |
| 14 | 95236 | Linden | 87 | A | 0 | $648K |
| 15 | 95336 | Manteca | 86 | A | 3 (1 health) | $523K |
| 16 | 95304 | Tracy | 84 | B | 2 (1 health) | $869K |
| 17 | 95220 | Acampo | 83 | B | 0 | $719K |
| 18 | 95337 | Manteca | 81 | B | 3 (1 health) | $611K |
| 19 | 95632 | Galt | 78 | B | 2 (1 health) | $488K |
| 20 | 95201 | Stockton | 77 | B | 9 (6 health) | — |
| 21 | 95202 | Stockton | 77 | B | 9 (6 health) | $322K |
| 22 | 95205 | Stockton | 77 | B | 9 (6 health) | $289K |
| 23 | 95208 | Stockton | 77 | B | 9 (6 health) | — |
| 24 | 95209 | Stockton | 77 | B | 9 (6 health) | $465K |
| 25 | 95210 | Stockton | 77 | B | 9 (6 health) | $337K |
| 26 | 95211 | Stockton | 77 | B | 9 (6 health) | — |
| 27 | 95213 | Stockton | 77 | B | 9 (6 health) | — |
| 28 | 95214 | Stockton | 77 | B | 9 (6 health) | — |
| 29 | 95267 | Stockton | 77 | B | 9 (6 health) | — |
| 30 | 95269 | Stockton | 77 | B | 9 (6 health) | — |
| 31 | 95296 | Stockton | 77 | B | 9 (6 health) | — |
| 32 | 95297 | Stockton | 77 | B | 9 (6 health) | — |
| 33 | 91775 | San Gabriel | 73 | B | 0 | $1043K |
| 34 | 94528 | Diablo | 73 | B | 0 | $2000K |
| 35 | 94913 | San Rafael | 73 | B | 0 | — |
| 36 | 94914 | Kentfield | 73 | B | 0 | — |
| 37 | 94979 | San Anselmo | 73 | B | 0 | — |
| 38 | 95227 | Clements | 73 | B | 0 | $730K |
| 39 | 95385 | Vernalis | 73 | B | 0 | — |
| 40 | 95203 | Stockton | 72 | B | 9 (6 health) | $350K |
| 41 | 95204 | Stockton | 72 | B | 9 (6 health) | $358K |
| 42 | 95206 | Stockton | 72 | B | 9 (6 health) | $389K |
| 43 | 95207 | Stockton | 72 | B | 9 (6 health) | $409K |
| 44 | 95212 | Stockton | 72 | B | 9 (6 health) | $499K |
| 45 | 95215 | Stockton | 72 | B | 9 (6 health) | $379K |
| 46 | 95219 | Stockton | 72 | B | 9 (6 health) | $540K |
| 47 | 94912 | San Rafael | 66 | C | 0 | — |
| 48 | 94978 | Fairfax | 66 | C | 0 | — |
| 49 | 95253 | Victor | 66 | C | 0 | — |
| 50 | 95697 | Yolo | 66 | C | 0 | — |
| 51 | 95231 | French Camp | 62 | C | 11 (11 health) | $478K |
| 52 | 94930 | Fairfax | 60 | C | 0 | $1152K |
| 53 | 94901 | San Rafael | 55 | C | 0 | $1370K |
| 54 | 94957 | Ross | 55 | C | 0 | $2000K |
| 55 | 94960 | San Anselmo | 55 | C | 0 | $1589K |
Recommended Buyer Guides for San Joaquin County
If FEMA records flag flood-top-risk status or EPA samples show PFAS exceedances, the matching logic lifts emergency-water and PFAS-rated filtration into the recommendations — federal data drives the order, not retailer arrangements.
- Best Lead Paint Test Kits — 60.4% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
Deep Dive Reports
Detailed analysis for San Joaquin County, California
Overview
San Joaquin County in California covers 55 ZIP codes with an average Home Safety Score of B (78/100).
32 of 55 ZIP codes have recorded EPA violations. 142 health-based violations have been documented.
← Back to California water quality report
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Home values: U.S. Census Bureau ACS (median estimates by ZCTA)
Updated daily.