Hamilton County, Ohio: drinking water report. Hamilton County – Cincinnati and its suburbs – serves about 830,000 residents.
Hamilton County – Cincinnati and its suburbs – serves about 830,000 residents. Greater Cincinnati Water Works (GCWW) draws from the Ohio River, which by the time it reaches Cincinnati has received discharges from Pittsburgh, Wheeling, and dozens of communities along its 981-mile course. GCWW operates one of the oldest continuously operating water treatment facilities in the country, with treatment upgrades added over the decades to address the river's complex and variable contamination profile.
The Ohio River is one of the most heavily utilized water sources in the eastern United States, and the contaminant mix at Cincinnati's intake reflects that. GCWW treats for a wide range of compounds, and the utility has invested in granular activated carbon filtration – unusual for a surface water plant – specifically to handle organic compounds and taste-and-odor issues.
UCMR5 data shows PFAS detections in the GCWW system. The Ohio River receives PFAS from upstream industrial discharges and municipal wastewater plants. According to the Ohio EPA's 2024 compliance data, GCWW's PFAS readings were below proposed federal MCLs, but the utility has flagged emerging contaminant monitoring as a priority.
The Ohio River's complexity means GCWW treats for more contaminants than most utilities. But individual building plumbing – particularly in Cincinnati's older housing stock – can introduce lead after water leaves the treatment system.
Check your water for data specific to your area. GCWW's carbon filtration already provides some PFAS reduction, but a home RO system adds another layer. Our water filter guide helps you decide what makes sense. Pull your detailed report, and see our Ohio page for statewide data.