CITY REPORT
MO
O Fallon, MO Water Quality Report
1 ZIP code · 5 water systems · Updated 2026-03-16
Data: EPA SDWIS Last verified: 2026-03-16
1
ZIP Codes
5
Water Systems
1
ZIPs with Violations
Zone 1
Radon Risk (High)
Overview
We track water quality and home safety data for 1 ZIP code in O Fallon, Missouri, covering 5 community water systems serving approximately 100,587 people.
1 of 1 ZIP code (100%) have recorded EPA violations. All violations are monitoring/reporting type.
Water Sources
O Fallon water systems draw from: Groundwater, Surface water.
Lead & Copper
- Lead data: not yet available for O Fallon
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 1 (High Risk)
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Contaminant 0700 | Other | 8 | 1 |
| Consumer Confidence Report Rule | Reporting | 2 | 1 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 63366 | — | 5 | 0 | ST CHARLES COUNTY PWSD 2 |
All ZIP Codes in O Fallon
- 63366 — 5 violations
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
Updated daily.