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Illinois Water Quality
1,134
Utilities in database
12.0M
Residents served
20%
On private wells
3
Key contaminants tracked
Drinking Water in Illinois
Illinois has 1,134 community water systems serving approximately 12.0 million residents. Primary water sources include groundwater. The most commonly reported contaminants include lead, disinfection byproducts, nitrates. 20% of Illinois residents rely on private wells. IEPA holds primary enforcement authority under the Safe Drinking Water Act.
Utilities in Illinois
926–950 of 1,134Glenbrook Sd
IL0315310 · 822 served
Sheffield
IL0110950 · 821 served
Exeter-merritt Water Coop
IL1710010 · 820 served
West Salem
IL0470200 · 819 served
Round Prairie Water Coop
IL1670090 · 813 served
Loami
IL1670700 · 812 served
Blairsville Pwd
IL1995350 · 807 served
New Memphis Pwd
IL0275350 · 805 served
Noble
IL1590150 · 805 served
Elizabeth
IL0850150 · 802 served
Shannon
IL0150300 · 801 served
Forest View
IL0310930 · 800 served
Lake Iroquois Association
IL0755200 · 800 served
Brownsville Water Project, Inc
IL1930020 · 800 served
Aqua Illinois-village Woods
IL1970060 · 800 served
Franklin
IL1370150 · 800 served
Braceville
IL0630050 · 800 served
Willisville
IL1450300 · 799 served
Mc Lean
IL1130850 · 791 served
Pearl City
IL1770400 · 790 served
Poplar Grove West-countryside
IL0070350 · 790 served
Dallas City
IL0674300 · 788 served
Kaho Public Water District
IL1170030 · 785 served
Ej Water-witt
IL1350850 · 785 served
Sherrard
IL1310400 · 785 served
Key Contaminant Concerns in Illinois
Lead
Lead is a naturally occurring heavy metal that was widely used in plumbing infrastructure until it was banned for new installations in 1986. An estimated 9.2 million lead service lines still connect homes to public water mains across the United States, along with millions of homes with lead solder in their internal plumbing.
Nitrates
Nitrate (NO₃⁻) is a nitrogen-containing compound that forms naturally through the decomposition of organic matter. At elevated concentrations — almost always from human activity — nitrate interferes with the blood's ability to carry oxygen. The United States produces over 23 million tons of nitrogen fertilizer annually, making agricultural runoff the dominant source of nitrate contamination.
DBPs
When utilities add chlorine to water to kill pathogens, it reacts with dissolved organic matter — leaves, algae, soil — to produce disinfection byproducts (DBPs). Over 600 DBPs have been identified. The EPA regulates two groups: total trihalomethanes (TTHMs, including chloroform) and haloacetic acids (HAA5). DBP levels tend to be highest in surface water systems and in warm months when organic matter is elevated.
Illinois Water FAQs
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Data source: Utility data from EPA SDWIS. 1,134 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-17