Clark County, Illinois
7 ZIP codes · Avg score 69/100 · Grade C · Updated 2026-06-03
Within Clark County, 7 tracked ZIP codes reveal moderate water quality — national standards are generally met, with some documented exceptions.
How Clark County Compares
How Clark County Compares
Clark County scores 8 points above the Illinois state average (61/100) and 1 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: Clark County, Illinois
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 13.8 (asthma 10.3%, diabetes 12%)
Estimated additional annual cost per homeowner: $890, driven primarily by energy_code_gap
Infrastructure: 0.421% avg pipe failure probability, 71% of ZIPs at high risk
67.1% of homes built before 1978 (lead paint era)
Violation History (2021–2022)
→ Stable trendEPA violation counts by year across Clark County water systems. Health-based shown in red, total in blue.
Peak year: 2021 with 2 violations. Past 5 years: 4 total (4 health-based).
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: $890
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
7,704 housing units in Clark 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 Clark County
Remediation costs are relatively manageable for most homeowners in Clark 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 Clark 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 Clark County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Westfield | 678 | 17 |
| 2 | Casey | 3,274 | 5 |
| 3 | Martinsville | 1,200 | 5 |
| 4 | Ej Water Cooperative | 29,720 | 4 |
| 5 | Greenup | 1,513 | 4 |
8 total water systems serve Clark County.
All ZIP Codes in Clark County
7 ZIP codes tracked in Clark County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 62441 | Marshall | 80 | B | 3 | $140K |
| 2 | 62442 | Martinsville | 76 | B | 1 | $85K |
| 3 | 62474 | Westfield | 75 | B | 17 (2 health) | $85K |
| 4 | 62477 | West Union | 74 | B | 2 | $152K |
| 5 | 62478 | West York | 63 | C | 0 | $132K |
| 6 | 62420 | Casey | 62 | C | 4 (1 health) | $122K |
| 7 | 62423 | Dennison | 53 | D | 0 | $148K |
Recommended Buyer Guides for Clark County
Editorial methodology pairs each documented risk in this county with the buyer category that addresses it, drawing on water-quality detections, housing-stock lead exposure, EPA Radon Zone designation, and FEMA flood and wildfire ratings. NSF-certified options surface where applicable, and products that match the specific contaminant take priority.
- Best Lead Paint Test Kits — 67.1% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
Deep Dive Reports
Detailed analysis for Clark County, Illinois
Overview
Clark County in Illinois covers 7 ZIP codes with an average Home Safety Score of C (69/100).
5 of 7 ZIP codes have recorded EPA violations. 3 health-based violations have been documented.
← Back to Illinois 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.