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.