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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
526–550 of 1,134Akin Water District
IL0555120 · 2,368 served
Lick Creek Pwd
IL1815100 · 2,365 served
Hickory-kerton Wtr Coop
IL1695200 · 2,358 served
Polo
IL1410450 · 2,355 served
Seneca
IL0991050 · 2,353 served
Davis Junction
IL1410030 · 2,344 served
Otter Creek Lake Utilities District
IL2015320 · 2,342 served
Thornton
IL0313090 · 2,333 served
Egyptian Water Company
IL1570010 · 2,330 served
Aqua Illinois-timber Ridge
IL1970410 · 2,322 served
Oblong
IL0330150 · 2,321 served
White Hall
IL0610400 · 2,313 served
Altamont
IL0490050 · 2,300 served
Lake Barrington Shores Subdivsion
IL0975520 · 2,300 served
Arthur
IL1394040 · 2,300 served
Prairie Path Water Company-galena
IL0855050 · 2,294 served
Prospect Heights
IL0312530 · 2,280 served
T-l Rural Water District
IL1430030 · 2,243 served
Henry
IL1230050 · 2,230 served
Elwood
IL1970350 · 2,229 served
Tamaroa
IL1450250 · 2,197 served
Pecatonica
IL2010250 · 2,195 served
Mount Olive
IL1170700 · 2,193 served
Southwater Inc
IL0030020 · 2,185 served
Groveland Township Water District
IL1795200 · 2,185 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