O Fallon

O Fallon, MO receives a water quality score of 82/100 (Grade B) based on EPA Safe Drinking Water Information System (SDWIS) compliance data for 5 public water systems serving the area.

O Fallon's water quality is above the national average, with strong compliance records and low contaminant levels. Residents generally receive clean, safe tap water that meets EPA standards.

O Fallon's score of 82 is 4 points above the Missouri state average of 78, and above the nationwide average of roughly 78/100 across all U.S. states.

Homeowners in the mid-size city of O Fallon, Missouri, receive their tap water from one of several distinct distribution systems, which draw from a region shaped by the agricultural plains near the Mississippi and Missouri river confluence. While the area's water quality generally aligns with solid safety standards, the surrounding agricultural landscape introduces runoff challenges typical of the Midwest. Consequently, prospective homebuyers might experience slight differences in tap water characteristics depending on which utility serves their property, though the city's supply remains highly dependable overall.

Water quality data is sourced from the U.S. EPA SDWIS database and updated quarterly. Learn about our scoring methodology → Read our Missouri water quality rankings report →