Peoria County, Illinois: drinking water report. Peoria County in central Illinois has about 181,000 residents, with Peoria as the county seat.
Peoria County in central Illinois has about 181,000 residents, with Peoria as the county seat. Illinois American Water draws from the Illinois River and groundwater from the Sankoty-Mahomet Aquifer. The Illinois River at Peoria has traveled through some of the most intensive agricultural land in the country, carrying the nutrients and chemicals that the landscape sheds.
The Illinois River at Peoria carries elevated nitrate from upstream agriculture. According to the Illinois EPA's 2024 river monitoring data, nitrate at the Peoria intake averaged 6.2 mg/L during spring – well below the MCL but high enough to indicate substantial agricultural influence. Atrazine follows the same seasonal pattern, peaking at 1.8 ppb during May-June.
Caterpillar's global headquarters and manufacturing operations in Peoria have contributed industrial contamination to specific sites in the county. The General Wayne A. Downing Peoria International Airport has documented AFFF use. Illinois EPA's 2024 PFAS investigation found PFOS at 8 ppt in monitoring wells near the airport.
Peoria's Illinois River supply is treated to meet all standards, and the Sankoty-Mahomet Aquifer groundwater supplement is naturally well-filtered. The primary household concerns are the agricultural contaminants in the river supply and trace PFAS from regional sources.
Check your water for current results. A carbon filter handles atrazine and disinfection byproducts. For PFAS, reverse osmosis adds comprehensive protection. Our water filter guide covers both options. Get your detailed report for seasonal patterns, and visit our Illinois page for statewide context.
Drinking water is one exposure route. These federal datasets also cover Peoria County, IL.
The EPA places Peoria County, IL in Zone 1 - the EPA's highest-risk category, where the predicted average indoor radon level is above 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
72% of homes in Peoria County, IL were built before 1980, and 29% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Peoria County, IL averages 9 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide