Marion County, Indiana: drinking water report. Marion County is coterminous with the City of Indianapolis, serving about 980,000 residents.
Marion County is coterminous with the City of Indianapolis, serving about 980,000 residents. Citizens Water (formerly Indianapolis Water Company) draws from three sources: the White River, Fall Creek, and Geist and Morse reservoirs. The system also uses a small amount of groundwater. Indianapolis sits in the central Indiana agricultural belt, and the White River receives runoff from one of the most intensively farmed landscapes in the Midwest.
The White River's agricultural watershed means elevated nutrient levels and seasonal spikes in organic content that drive disinfection byproduct formation. Citizens Water has invested in advanced treatment including ozone and biologically active filtration to manage these seasonal challenges.
UCMR5 data shows low-level PFAS detections in the Indianapolis water system. Indiana does not have state-specific PFAS standards. According to the Indiana Department of Environmental Management's 2024 compliance data, the Citizens Water system met all federal contaminant limits, though disinfection byproduct levels fluctuated seasonally. The city's combined sewer system also creates periodic water quality events during heavy rainfall, when combined sewer overflows discharge into the White River upstream of some intake points.
Seasonal variation matters in Marion County – summer and fall bring higher treatment chemical demand and more variable water quality.
Check your water for current monitoring data. An activated carbon filter reduces disinfection byproducts and chlorine taste. For PFAS, reverse osmosis provides stronger protection. Our water filter guide helps you choose. Pull your detailed report, and visit our Indiana page for statewide context.