- EPA's UCMR 5 testing looked for 30 contaminants here and found 3.
- Lithium: found in 10 of 12 samples, average 31.6 µg/L, highest 71.3 µg/L (EPA UCMR 5 testing, Feb 2024–Sep 2025)
- PFBA (a PFAS): found in 1 of 12 samples, average 0.50 ppt, highest 6.1 ppt (EPA UCMR 5 testing, Feb 2024–Sep 2025)
- PFPeA (a PFAS): found in 1 of 12 samples, average 0.30 ppt, highest 3.4 ppt (EPA UCMR 5 testing, Feb 2024–Sep 2025)
- Lead, 90th percentile: 1.48 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2023–Dec 31, 2025). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
Public EPA test results
Can you drink O'Fallon tap water? What EPA records show
EPA MO6010588 · serves O Fallon, MO · about 32,515 people (EPA SDWIS)
This report shows EPA's federal records for this water system: UCMR 5 testing, lead testing and violations. It isn't a test of the water at your tap, and it has no Water Score.
Public EPA test results
Ofallon PWS (EPA MO6010588)
EPA data as of October 14, 2026. For O'Fallon's main utility, Ofallon PWS: We found no health-based violations in EPA's records for this system (MO6010588) since July 1, 2021, as of October 14, 2026. PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
What EPA records show for Ofallon PWS, as of October 14, 2026
We found no health-based violations in EPA's records for this system (MO6010588) since July 1, 2021, as of October 14, 2026.
Source: EPA ECHO record for Ofallon PWS (SDWIS). Data as of October 14, 2026.
Lead, 90th percentile: 1.48 ppb at the latest result in EPA records for a monitoring period that ran on or after July 1, 2021, at or below EPA's 15 ppb action level (EPA SDWIS, monitoring period Jan 1, 2023–Dec 31, 2025). The 90th percentile is a system-wide measure from homes sampled under EPA's lead rule; it isn't a result for your home.
EPA's UCMR 5 testing looked for 30 contaminants here and found 3.
PFOA and PFOS were not detected at or above EPA's reporting level in EPA's UCMR 5 testing.
Source: EPA records (SDWIS, UCMR 5). SDWIS: data as of Oct 14, 2026. EPA UCMR 5 data, samples through June 2026.
Your water bill names your utility.
Does Ofallon PWS use chloramine?
EPA treatment records (state-reported) list chloramines for Ofallon PWS. EPA record