Ofallon Public Water System
EPA ID: MO6010588 · 32,515 people served · 4 ZIP codes
In the most recent five-year monitoring window, Ofallon Public Water System posted zero EPA violations serving 32,515 residents.
Data: EPA SDWIS Last verified: 2026-04-02
Service Area Map
Coverage area for Ofallon Public Water System Source: EPA SDWIS service area boundaries.
Service area boundary
Service Area Demographics
The Ofallon Public Water System serves a community with a median household income of $105,044 and an estimated 225,607 residents across its service area.
🌊 Where Does Your Water Come From?
Ofallon Public Water System's water is drawn from rivers, lakes, or reservoirs. Surface water sources are more exposed to agricultural runoff, stormwater, and upstream discharges, but they typically receive more intensive treatment before reaching your tap.
About 1% of homes in St. Charles County, Missouri rely on private wells rather than public water systems. Private well owners are responsible for their own water testing and treatment.
Superfund Proximity Note: This service area ranks in the 70th percentile nationally for proximity to Superfund (NPL) sites.
Infrastructure Risk
PFAS Detected in Service Area
PFAS ("forever chemicals") have been detected in water serving this system's area. 8 detections recorded. 1 exceeds federal EPA limits (4 ppt for PFOA/PFOS).
Comparable Water Systems
Similar-sized systems in Missouri
Estimated Remediation Costs
Average estimated costs across ZIP codes served by this system
Based on national averages for common remediation projects. Actual costs vary by property. Only issues flagged by EPA, FEMA, or state data for each ZIP code are included.
System Overview
Ofallon Public Water System (EPA ID: MO6010588) is a community water system in Missouri that serves approximately 32,515 people from surface water sources.
This system provides water to 4 ZIP codes across 3 communities.
Violation History
Lead & Copper
No Lead and Copper Rule sampling data available for this water system.
Need help with your water quality?
Typical cost: Water test: typically $20–$50 (DIY kit) · Professional inspection: $150–$400
Find the Right Water FilterFree tip: Let cold water run for 2 minutes before drinking — this helps flush lead from your pipes.
ZIP Codes Served
Coverage: 3 ZIP codes confirmed via EPA Community Water System Service Area Boundaries v3 plus 1 additional ZIP inferred from SDWIS registry data. The EPA-confirmed set is the most reliable; SDWIS-inferred entries may be narrower than the real deployment area.
Data Sources
This report uses public data from the EPA Safe Drinking Water Information System (SDWIS). View the full compliance record for Ofallon Public Water System (MO6010588) on EPA.gov.
Frequently Asked Questions
Is Ofallon Public Water System water safe to drink?
Based on EPA records, Ofallon Public Water System has no recorded violations in the past 5 years — a positive indicator of water quality management.
How many people does Ofallon Public Water System serve?
Ofallon Public Water System serves approximately 32,515 people across 4 ZIP codes in Missouri.
Where does Ofallon Public Water System get its water?
The primary water source is surface water.
Federal UCMR5 PFAS Monitoring: Detected
This water system was tested under the federal EPA Unregulated Contaminant Monitoring Rule (UCMR5). PFAS compounds were detected below the current state-enforceable MCL.
Current MCL reflects the lowest state-enforceable limit (NYS 10 ppt for PFOA/PFOS, effective August 2020). The federal final MCL of 4 ppt for PFOA/PFOS (EPA April 2024 rule) is not enforceable until April 2029. Detections above 4 ppt but below 10 ppt are below current MCL but above the future federal limit.
Source: U.S. EPA UCMR5 (Unregulated Contaminant Monitoring Rule, 5th cycle) — per-system federal sampling, 2023–2025. EPA UCMR5 monitoring program →
Lead Service Line Inventory
Service line breakdown reported under the federal Lead and Copper Rule Improvements (LCRI) inventory requirement:
Federal LCRI rule (effective October 2024) requires every public water system to inventory its service lines and complete lead-line replacement within 10 years.
Source: EPA SDWIS Federal Service Line Inventory (Phase 2) · Submitted 2026
ZipCheckup is not affiliated with the utility or state agency. Inventory figures render verbatim from the public LCRI submission cited above; ZipCheckup does not perform inspections or replacements.
How Water Systems Appear in Rankings
Water systems are evaluated by violation history, contaminant detections, and service population. Larger systems with more service connections appear in more rankings.
- #30 / 50 Highest Exposure Burden (Missouri)