Water Quality in O Fallon, MO: 10 Violations - Grade N/A
5 water systems · 2 directly mapped ZIP records
Available EPA records report 10 violations across 2 directly mapped ZIP records with known counts for O Fallon. This is compliance evidence, not a property-level tap-water verdict.
Data: EPA Safe Drinking Water Information System (SDWIS)
Water Quality by ZIP Code in O Fallon
This table shows typed EPA water evidence only. Missing violation counts are displayed as N/A, not zero.
| ZIP Code | Violations | Health | |
|---|---|---|---|
| 63366 | 10 | 0 | View report → |
| 63368 | 2 | 0 | View report → |
Water Quality Overview
O Fallon, Missouri has directly mapped EPA water-system data for 2 ZIP codes. This page reports typed compliance facts and does not relabel the multi-source Home Safety Score as a drinking-water grade.
The available EPA records report 10 violations (all classified as monitoring/reporting type in the available record) across 2 directly mapped ZIP records with reported counts.
Lead Levels
The average 90th percentile lead level across O Fallon water systems is 0.0029 mg/L - within EPA limits. No exceedances appear among the 2 ZIP records with known lead status.
Water Systems Serving O Fallon
O Fallon is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 100,311 people across 2 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 18 enforcement actions against water systems serving O Fallon. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in O Fallon
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels and violation history
Request your CCR - your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test - certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration - NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories - monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in O Fallon Water Systems
The following contaminants have been detected or caused violations across O Fallon's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Stage 1 DBP Rule | Treatment Technique | N/A | 3 | 1 | No |
| Surface Water Treatment Rule | Treatment Technique | N/A | 3 | 1 | No |
| Stage 2 DBP Rule | Treatment Technique | N/A | 1 | 1 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
EPA Enforcement History
The EPA and state regulators have taken 9 enforcement actions against water systems serving O Fallon. Recent actions:
| Date | Action Type |
|---|---|
| 2025-09-03 | State Order Extension |
| 2025-08-22 | State Informal Action |
| 2025-07-21 | State Informal Action |
| 2025-07-21 | State Informal Enforcement |
| 2025-04-14 | State Order Extension |
| 2022-07-22 | State Informal Action |
| 2022-07-06 | State Order Extension |
| 2021-08-02 | State Informal Action |
| 2021-08-02 | State Informal Enforcement |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-09-03.
O Fallon vs. Nearby Missouri Cities
How O Fallon's water quality compares to similar cities in Missouri:
| City | Direct EPA ZIPs | Violations | Systems | Population |
|---|---|---|---|---|
| O Fallon | 2 | 10 | 5 | 100,311 |
| Ballwin | 2 | 4 | 6 | 92,571 |
| Lees Summit | 6 | 18 | 9 | 109,974 |
| Florissant | 3 | 0 | 1 | 112,073 |
Recommended Water Filters for O Fallon
Based on contaminants detected in O Fallon's water supply, these filter types are recommended:
Reverse Osmosis (under-sink)
- Removes: Lead
- Effectiveness: 95-99%
- Cost range: $150–$500
- Certification: NSF/ANSI 58
- Recommended products:
- Waterdrop G3P800
- Aquasana AQ-5200
- Clearly Filtered Pitcher
Common Questions About O Fallon Water
These are the most common questions residents search for about water quality in O Fallon, Missouri:
Is O Fallon water hard or soft? Water hardness varies by source. O Fallon's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink O Fallon tap water? City-level EPA records cannot determine safety at a specific tap. No health-based violations are recorded across 2 directly mapped ZIP records with known counts, but this is not a property-level safety guarantee.
What is the best water filter for O Fallon? Based on detected contaminants, a reverse osmosis (under-sink) filter is most recommended. See our Water Filter Matcher for personalized recommendations.
O Fallon vs. Missouri Average
Understanding how O Fallon compares to the broader Missouri average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below - water quality can vary significantly even within O Fallon.
ZIP Codes in O Fallon
O Fallon spans 2 ZIP codes. EPA water-system coverage is available for 2 directly mapped ZIP codes. Check each ZIP code for detailed contaminant data, violation history, and system information.
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
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Source reporting periods vary. See each cited source for its publication schedule.