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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
726–750 of 1,134Assumption
IL0210050 · 1,315 served
Walnut
IL0111100 · 1,311 served
Milford
IL0750650 · 1,306 served
Taylorville Correctional Center
IL0210010 · 1,300 served
Blue Mound
IL1150100 · 1,300 served
Wyoming
IL1750200 · 1,300 served
Prairie Path Water Company-lake Wildwood
IL1235200 · 1,295 served
Countryside Lake Subdivision -lake Co Pw
IL0975200 · 1,287 served
New Hope Waterworks Corp
IL1915100 · 1,285 served
Toledo
IL0350200 · 1,278 served
Il American-washington Estates
IL1797050 · 1,278 served
Petrolia Pwd
IL1015350 · 1,275 served
Chrisman
IL0450100 · 1,273 served
St Elmo
IL0510250 · 1,272 served
Cobden
IL1810150 · 1,267 served
Ladd
IL0110450 · 1,263 served
Valmeyer
IL1330250 · 1,263 served
Hartford
IL1190500 · 1,260 served
Chatsworth
IL1050100 · 1,256 served
Liberty-ledford Pwd
IL1655050 · 1,255 served
Hanna City
IL1430400 · 1,253 served
Lake Williamson Christian Center
IL1175100 · 1,250 served
Wayne City
IL1910450 · 1,239 served
Blackhawk Estates Llc
IL0317765 · 1,238 served
Prairie Path Water Company-killarney
IL1115400 · 1,232 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.
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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