Merced County, California
22 ZIP codes · Avg score 77/100 · Grade B · Updated 2026-06-03
Across Merced County's 22 ZIP codes, EPA compliance data shows above-average performance — violation rates are minimal, none of the county's systems have triggered health-based MCL exceedances in recent cycles, and the county's scores have stayed above the national baseline across every recent reporting period.
How Merced County Compares
How Merced County Compares
Merced County scores 4 points above the California state average (73/100) and 9 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Merced County, California
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 12.1 (asthma 9.8%, diabetes 13%)
Estimated additional annual cost per homeowner: $2,498, driven primarily by sea_level
Infrastructure: 0.342% avg pipe failure probability, 19% of ZIPs at high risk
59.8% of homes built before 1978 (lead paint era)
Violation History (2021–2025)
↑ Worsening trendEPA violation counts by year across Merced County water systems. Health-based shown in red, total in blue.
Peak year: 2024 with 57 violations. Past 5 years: 112 total (112 health-based). Health-based violations are rising versus the prior 2-year window — worth closer monitoring.
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: $2,498
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
87,294 housing units in Merced 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 Merced County
Remediation costs are relatively manageable for most homeowners in Merced 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 Merced 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 Merced County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Castle Airport | 1,650 | 28 |
| 2 | CITY OF MERCED | 93,692 | 25 |
| 3 | John Latoracca Correctional Facility | 800 | 25 |
| 4 | Black Rascal Water Company | 367 | 25 |
| 5 | Planada Csd | 4,164 | 21 |
21 total water systems serve Merced County.
All ZIP Codes in Merced County
22 ZIP codes tracked in Merced County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 95324 | Hilmar | 95 | A | 0 | $442K |
| 2 | 95301 | Atwater | 90 | A | 0 | $368K |
| 3 | 95334 | Livingston | 89 | A | 4 (2 health) | $346K |
| 4 | 95343 | Merced | 88 | A | 5 (1 health) | — |
| 5 | 95344 | Merced | 88 | A | 5 (1 health) | — |
| 6 | 95315 | Delhi | 86 | A | 1 | $338K |
| 7 | 95303 | Ballico | 85 | A | 1 (1 health) | $602K |
| 8 | 95322 | Gustine | 83 | B | 2 (1 health) | $433K |
| 9 | 95369 | Snelling | 83 | B | 0 | $351K |
| 10 | 93635 | Los Banos | 82 | B | 7 (4 health) | $424K |
| 11 | 95388 | Winton | 78 | B | 3 (2 health) | $308K |
| 12 | 95340 | Merced | 76 | B | 5 (1 health) | $383K |
| 13 | 95341 | Merced | 76 | B | 5 (1 health) | $295K |
| 14 | 95348 | Merced | 76 | B | 5 (1 health) | $353K |
| 15 | 95365 | Planada | 73 | B | 2 (1 health) | $237K |
| 16 | 93661 | Santa Rita Park | 66 | C | 0 | — |
| 17 | 93665 | South Dos Palos | 66 | C | 0 | — |
| 18 | 95312 | Cressey | 66 | C | 0 | — |
| 19 | 95317 | El Nido | 66 | C | 0 | $396K |
| 20 | 95374 | Stevinson | 66 | C | 0 | $436K |
| 21 | 95333 | Le Grand | 62 | C | 9 (8 health) | $310K |
| 22 | 93620 | Dos Palos | 55 | C | 16 (15 health) | $295K |
Recommended Buyer Guides for Merced County
Editorial-only picks, screened against the EPA detections on file.
- Best Lead Paint Test Kits — 59.8% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
Deep Dive Reports
Detailed analysis for Merced County, California
Overview
Merced County in California covers 22 ZIP codes with an average Home Safety Score of B (77/100).
14 of 22 ZIP codes have recorded EPA violations. 39 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.