Franklin County, Ohio: drinking water report. Franklin County – Columbus and its suburbs – serves approximately 1.3 million residents.
Franklin County – Columbus and its suburbs – serves approximately 1.3 million residents. The City of Columbus draws from three reservoirs: Hoover, O'Shaughnessy, and Griggs, all fed by the Scioto River and its tributaries. The city operates three water treatment plants and provides wholesale service to several suburban communities. The Scioto watershed drains agricultural land across central Ohio, which shapes the contaminant profile of the source water.
Columbus faces a challenge common to Midwest cities drawing from agricultural watersheds: seasonal algal blooms that produce microcystins and other cyanotoxins. Ohio's experience with the 2014 Toledo water crisis – caused by a Lake Erie algal bloom – led to statewide investments in algal toxin monitoring. Franklin County's reservoirs are susceptible to blooms during warm, nutrient-rich conditions.
UCMR5 data shows low-level PFAS detections in the Columbus water system. Ohio does not have state-specific PFAS MCLs, relying on federal standards. According to the Ohio EPA's 2024 compliance data, the Columbus system met all federal contaminant limits but recorded disinfection byproduct levels that fluctuated seasonally with changes in source water organic content.
Seasonal variation is the key dynamic in Franklin County – water quality shifts with rainfall, temperature, and agricultural activity in the watershed.
Check your water for the latest monitoring data in your area. An activated carbon filter handles both disinfection byproducts and provides some PFAS reduction. Our water filter guide covers which certifications to look for. Pull your detailed report for seasonal trends, and visit our Ohio page for statewide data.