St. Clair County, Illinois
30 ZIP codes · Avg score 68/100 · Grade C · Updated 2026-06-03
Water monitoring across St. Clair County's 30 ZIP codes paints a mid-range picture — solid compliance in some zones, documented concerns in others; most violations on record are concentrated in specific prior years rather than spread evenly across the full compliance history, and the overall county grade has held steady in the middle tier without major shifts in either direction.
How St. Clair County Compares
How St. Clair County Compares
St. Clair County scores 7 points above the Illinois state average (61/100) and 0 points above the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-03
ZIP Code Risk Map
Water Quality Map: St. Clair County, Illinois
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 13.7 (asthma 11.1%, diabetes 13.1%)
Estimated additional annual cost per homeowner: $1,600, driven primarily by flood
Infrastructure: 0.385% avg pipe failure probability, 43% of ZIPs at high risk
64.2% of homes built before 1978 (lead paint era)
Violation History (2024–2025)
→ Stable trendEPA violation counts by year across St. Clair County water systems. Health-based shown in red, total in blue.
Peak year: 2024 with 25 violations. Past 5 years: 29 total (29 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: $1,600
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
110,629 housing units in St. Clair 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 St. Clair County
Remediation costs are relatively manageable for most homeowners in St. Clair 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 St. Clair 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 St. Clair County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Il American-east St Louis | 131,368 | 76 |
| 2 | MEADOWBROOK MH COMMUNITY, LLC | 463 | 70 |
| 3 | Arapaho Village Mhp | 368 | 70 |
| 4 | O Fallon | 46,603 | 47 |
| 5 | Smithton | 4,006 | 28 |
28 total water systems serve St. Clair County.
All ZIP Codes in St. Clair County
30 ZIP codes tracked in St. Clair County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 62001 | Alhambra | 83 | B | 1 | $209K |
| 2 | 62225 | Scott Air Force Base | 83 | B | 0 | — |
| 3 | 62289 | Summerfield | 83 | B | 0 | $74K |
| 4 | 62222 | Belleville | 81 | B | 14 (2 health) | — |
| 5 | 62224 | Mascoutah | 81 | B | 1 | — |
| 6 | 62257 | Marissa | 80 | B | 4 | $119K |
| 7 | 62243 | Freeburg | 78 | B | 6 | $268K |
| 8 | 62254 | Lebanon | 78 | B | 1 | $197K |
| 9 | 62220 | Belleville | 76 | B | 14 (2 health) | $141K |
| 10 | 62221 | Belleville | 76 | B | 14 (2 health) | $207K |
| 11 | 62223 | Belleville | 76 | B | 14 (2 health) | $150K |
| 12 | 62226 | Belleville | 76 | B | 14 (2 health) | $163K |
| 13 | 62258 | Mascoutah | 76 | B | 1 | $230K |
| 14 | 62269 | O Fallon | 76 | B | 2 | $274K |
| 15 | 62260 | Millstadt | 75 | B | 1 | $230K |
| 16 | 62255 | Lenzburg | 71 | B | 2 | $153K |
| 17 | 62239 | Dupo | 69 | C | 5 | $112K |
| 18 | 62264 | New Athens | 68 | C | 4 | $137K |
| 19 | 62285 | Smithton | 68 | C | 3 | $265K |
| 20 | 62240 | East Carondelet | 65 | C | 0 | $85K |
| 21 | 62059 | Lovejoy | 63 | C | 0 | $37K |
| 22 | 62232 | Caseyville | 63 | C | 1 | $115K |
| 23 | 62208 | Fairview Heights | 55 | C | 0 | $168K |
| 24 | 62202 | East Saint Louis | 53 | D | 0 | — |
| 25 | 62282 | Saint Libory | 53 | D | 0 | $169K |
| 26 | 62204 | East Saint Louis | 50 | D | 0 | $48K |
| 27 | 62205 | East Saint Louis | 50 | D | 0 | $46K |
| 28 | 62206 | East Saint Louis | 50 | D | 0 | $58K |
| 29 | 62207 | East Saint Louis | 50 | D | 0 | $54K |
| 30 | 62203 | East Saint Louis | 45 | D | 0 | $73K |
Recommended Buyer Guides for St. Clair County
Methodologically, the recommendation order reflects severity in the federal record: contaminants flagged in EPA detection records for this county outrank generic water concerns, FEMA-confirmed hazard ratings shift emergency-related categories upward, and CDC lead-exposure markers govern when lead-test kits and certified filters appear at the top of the list.
- Best Lead Paint Test Kits — 64.2% of homes built before 1978
- Best Under-Sink Reverse Osmosis Systems — Multi-contaminant removal at the kitchen tap
- Best Sump Pumps — Flood is the top compound risk factor
- Best Mold Test Kits — Flood-driven moisture and mold risk
Deep Dive Reports
Detailed analysis for St. Clair County, Illinois
Overview
St. Clair County in Illinois covers 30 ZIP codes with an average Home Safety Score of C (68/100).
18 of 30 ZIP codes have recorded EPA violations. 10 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.