O Fallon, IL Water Quality
What's in O Fallon's water?
O Fallon has a health-based violation on record, but none in the last five years - an older issue, not necessarily a current one. 46,603 people get their water from it, across 18,497 connections.
O Fallon's record against the rest of the country
Out of 12,903 systems in this dataset, O Fallon ranks 1,092th by violation burden (92th percentile) - 29 violations total, 17 health-based.
Against the IL average
IL's 572 covered systems average 5.1 health-based violations each; O Fallon carries 17, more than typical for the state. See the lead and copper guide for why lead counts differently.
Most recent violation on record
O Fallon's most recent violation on record is dated 2026-01-01, with the most recent health-based one dated 1999-01-07. Last reported to EPA: 05/27/2026.
The concern categories on record
O Fallon's flagged contaminants and rule violations, grouped by what they actually mean for a filter choice rather than left as EPA's raw code list:
- Lead & copper - flagged from: Lead and Copper Rule
- Microbial contamination / treatment technique - flagged from: Coliform (TCR)
The most severe category on record is lead & copper, which points toward a lead-class filter if you want to address it directly.
What O Fallon's record does not cover
Everything on this page is O Fallon's own reported record under the Safe Drinking Water Act - a regulatory filing, not a sample of your tap. Between the utility's meter and O Fallon's customers' taps is household plumbing, invisible to a system-level record ranked 1,092th of 12,903 by violation count. The guide to what this data misses covers that gap.