O Fallon, MO: 12 Violations — 69/100 (2026)
2 ZIP codes · 8 water systems · Updated 2026-06-03
O Fallon shows moderate tap water quality for MO — some areas carry documented EPA violations while others meet standards without issues.
How O Fallon Compares
Data: EPA SDWIS Last verified: 2026-06-03
What You Should Know About O Fallon Water
- Your city's water systems recorded 12 violations in the past 5 years.
- Average lead level: 0.0011 mg/L.
- Homes built before 1986: 19% — older plumbing may contain lead solder.
- Estimated remediation: $2,400 per household.
- CDC health risk index: 11.99.
Who Supplies Your Water in O Fallon
Throughout O Fallon, MO, water comes from one of 3 primary utilities out of 8 total systems — independent providers with different rate structures, infrastructure, and compliance records that vary across the service territory.
Overview
We track water quality and home safety data for 2 ZIP codes in O Fallon, Missouri (population ~100,311), covering 8 community water systems serving approximately 1,292,378 people region-wide.
2 of 2 ZIP codes (100%) have recorded EPA violations. All violations are monitoring/reporting type.
Home Safety Score
Average Home Safety Score for O Fallon: C (69/100)
The score combines three factors:
| Factor | What It Measures |
|---|---|
| Water Quality | EPA violations and compliance history |
| Lead Levels | 90th percentile lead concentration vs EPA action level |
| Radon Risk | EPA radon zone classification |
Water Sources
O Fallon water systems draw from: Groundwater, Surface water.
Lead & Copper
- Average lead level (90th percentile): 0.0011 mg/L (EPA action level: 0.015 mg/L)
- 0 ZIP codes exceed the EPA lead action level
Radon Risk
Dominant radon zone: Zone 2 (Moderate Risk)
- Zone 1 (High): 0 ZIP codes
- Zone 2 (Moderate): 2 ZIP codes
- Zone 3 (Low): 0 ZIP codes
The EPA recommends testing homes in Zone 1 and Zone 2 areas for radon.
Top Contaminants
| Contaminant | Category | Violations | ZIPs Affected |
|---|---|---|---|
| Consumer Confidence Report Rule | Reporting | 6 | 2 |
| Contaminant 0700 | Other | 6 | 2 |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 3 | 2 |
| Stage 1 DBP Rule | Treatment Technique | 3 | 2 |
Areas with Most Violations
| ZIP Code | Safety Score | Violations | Health-Based | System |
|---|---|---|---|---|
| 63366 | C | 6 | 0 | St Charles County Pwsd 2 |
| 63368 | B | 6 | 0 | St Charles County Pwsd 2 |
All ZIP Codes in O Fallon
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.
Health Outcomes in O Fallon
Source: CDC PLACES (County-level estimates). Water contamination can correlate with respiratory and chronic health conditions.
Compared to National Average
Vertical line = national average. ■ Above national · ■ Below national
Top Contaminants in O Fallon Water
Based on EPA violation records. Check your ZIP code report for system-specific contaminant data.
Housing & Infrastructure in O Fallon
Housing age data helps assess potential lead pipe and infrastructure risks. Newer housing stock generally means lower plumbing-related contamination risk.
Source: U.S. Census Bureau American Community Survey (ACS).
Housing Age Profile
Post-1986 construction is where the lower lead-solder risk lives, because that's when the federal ban on lead solder in plumbing took effect. In O Fallon, where the median build year is 1991, the housing stock falls broadly on the newer side of that threshold — a distribution that moderates aggregate plumbing-era risk compared to older housing markets.
Most homes in O Fallon were built after 1986, reducing the risk of lead contamination from plumbing. Older homes should still be tested.
Source: U.S. Census Bureau ACS B25034.
Cost Context: What Remediation Means for O Fallon Homeowners
In O Fallon, the equity impact of remediation is proportionally small — not the kind of financial commitment that rises to the level of a genuine planning constraint, but a minor share of what most properties here are worth.
Remediation costs in O Fallon are relatively low compared to home values. The $1,300–$3,750 estimated range is a small fraction of median property value. Home values are 87% above the Missouri average.
Lead Exposure Risk for Children in O Fallon
Why children are most at risk: The CDC states there is no safe level of lead exposure for children. Children under 6 absorb lead more readily than adults, and even low levels can cause developmental delays, learning difficulties, and behavioral problems.
19% of housing in O Fallon predates the federal action against lead solder — a contained share — and aggregate readings stay beneath the regulatory benchmark. Lead therefore sits in a quiet position on the local water-quality picture, with single-home draws as the standard tool for confirming any one address.
Sources: EPA Lead and Copper Rule, U.S. Census Bureau ACS, CDC childhood lead poisoning prevention guidelines.
Flood & Climate Risk in O Fallon
347 FEMA flood insurance claims are on file for O Fallon, and 100% of local ZIP codes fall within federally designated flood zones — enough to put flood exposure on the planning radar, though short of the concentrated-risk threshold where treatment-system vulnerability becomes a primary consideration.
O Fallon has a moderate flood history with 347 FEMA claims averaging $14,185 per payout. 100% of ZIP codes fall within FEMA flood zones. Flood events can contaminate drinking water and overwhelm treatment systems.
How flooding affects water quality: Flood events can introduce sewage, agricultural runoff, and industrial chemicals into water supplies. Even after floodwaters recede, contamination can persist in wells and aging infrastructure. Flood damage can add significantly to the estimated <strong>$2,400</strong> remediation cost per household.
Residents in flood-prone areas should consider flood insurance even outside FEMA zones — over 25% of flood claims come from low-to-moderate risk areas. After any flood event, test your water before drinking.
Source: FEMA National Flood Insurance Program (NFIP) claims data, FEMA flood zone designations.
What You Can Do in O Fallon
- Test your water at home. City-level data shows averages — your tap may differ. NSF-certified test kits cost $20-40 and give results in days.
- Install a certified water filter. Filters rated for Consumer Confidence Report Rule can reduce the most common contaminant found in O Fallon's water.
- Check your home's plumbing. Homes built before 1986 may have lead solder in pipes. A licensed plumber can assess your risk.
Deep Dive Reports
Detailed analysis for O Fallon, MO