St. Louis County, Missouri
8 ZIP codes · Avg score 66/100 · Grade C · Updated 2026-06-04
Current EPA records place St. Louis County in the middle tier for drinking water safety, with 8 ZIP codes showing a range of outcomes.
How St. Louis County Compares
How St. Louis County Compares
St. Louis County scores 3 points below the Missouri state average (69/100) and 2 points below the national average (68/100).
Data: EPA SDWIS Last verified: 2026-06-04
ZIP Code Risk Map
Water Quality Map: St. Louis County, Missouri
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Key Risk Factors
Health risk index: 12.5 (asthma 10.6%, diabetes 11.5%)
Estimated additional annual cost per homeowner: $1,810, driven primarily by flood
Infrastructure: 0.365% avg pipe failure probability, 25% of ZIPs at high risk
46.5% of homes built before 1978 (lead paint era)
Violation History (2022–2025)
→ Stable trendEPA violation counts by year across St. Louis County water systems. Health-based shown in red, total in blue.
Peak year: 2024 with 13 violations. Past 5 years: 36 total (36 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: $1,810
Bar widths proportional to share of total annual risk cost. Source: compound risk model (FEMA, EPA, USGS).
Housing Age Distribution
57,575 housing units in St. Louis 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. Louis County
Remediation costs are relatively manageable for most homeowners in St. Louis 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. Louis 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. Louis County ranked by EPA violation count.
| # | Water System | Population | Violations |
|---|---|---|---|
| 1 | Mo American St Louis St Charles Counties | 1,111,000 | 31 |
| 2 | Mo American Ironton | 1,460 | 24 |
| 3 | Mo American Pevely Farms | 343 | 24 |
| 4 | Mo American Rogue Creek Utilities | 276 | 24 |
| 5 | Franklin County Pwsd 3 | 8,250 | 10 |
21 total water systems serve St. Louis County.
All ZIP Codes in St. Louis County
8 ZIP codes tracked in St. Louis County.
| # | ZIP Code | City | Safety Score | Grade | Violations | Home Value |
|---|---|---|---|---|---|---|
| 1 | 63055 | Labadie | 82 | B | 2 | $254K |
| 2 | 63099 | Fenton | 81 | B | 3 (2 health) | — |
| 3 | 63049 | High Ridge | 72 | B | 1 (1 health) | $209K |
| 4 | 63006 | Chesterfield | 66 | C | 8 (8 health) | — |
| 5 | 63025 | Eureka | 62 | C | 3 | $364K |
| 6 | 63026 | Fenton | 61 | C | 3 (2 health) | $282K |
| 7 | 63017 | Chesterfield | 56 | C | 8 (8 health) | $452K |
| 8 | 63005 | Chesterfield | 51 | D | 8 (8 health) | $671K |
Recommended Buyer Guides for St. Louis County
Filtered against EPA monitoring data and CDC lead-exposure guidance, the guides below skip the generic catalog and connect directly to the contaminants and hazards on file here.
- 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. Louis County, Missouri
Overview
St. Louis County in Missouri covers 8 ZIP codes with an average Home Safety Score of C (66/100).
8 of 8 ZIP codes have recorded EPA violations. 29 health-based violations have been documented.
← Back to Missouri 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.