Illinois
Cook County drinking water quality
423 active public water systems serve 5,279,874 people in Cook County. 203 are compliant, 220 had at least one EPA violation in the past three years, 43 are designated serious violators, and 5 carry a health flag.
Needs attention
37 more systems with a serious violator or health flag designation are in the lists below.
Community water systems
163 systems, largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Olympia Fields Olympia Fields |
4,922 | 3 | 1 | |
|
Palos Park Palos Park |
4,873 | 0 | 0 | |
|
Stone Park Stone Park |
4,576 | 1 | 1 | |
|
Hometown Hometown |
4,240 | 2 | 1 | |
|
Burnham Burnham |
3,989 | 7 | 3 | |
|
Rosemont Rosemont |
3,952 | 0 | 0 | |
|
South Chicago Heights South Chicago Heights |
3,924 | 1 | 0 | |
|
Indian Head Park Indian Head Park |
3,240 | 1 | 1 | |
|
Oasis MHP |
3,000 | 1 | 0 | |
|
Dixmoor Dixmoor |
2,973 | 5 | 4 | |
|
Mission Brook SD |
2,852 | 1 | 0 | |
|
South Palos Twsp Sanitary Dist |
2,800 | 3 | 0 | |
|
Kenilworth Kenilworth |
2,514 | 1 | 0 | |
|
Central Stickney SD |
2,400 | 3 | 0 | |
|
Thornton Thornton |
2,386 | 2 | 1 | |
|
Aqua Illinois-Timber Ridge Matteson |
2,322 | 0 | 0 | |
|
Prospect Heights Prospect Heights |
2,280 | 1 | 0 | |
|
Phoenix Phoenix |
1,994 | 4 | 2 | |
|
Merrionette Park Merrionette Park |
1,969 | 3 | 2 | |
|
Sterling Estates MHP Justice |
1,954 | 1 | 0 | |
|
IL American-Waycinden |
1,934 | 0 | 0 | |
|
Ford Heights East Chicago Heights |
1,813 | 4 | 3 | |
|
Hodgkins Hodgkins |
1,597 | 2 | 1 | |
|
East Hazel Crest East Hazel Crest |
1,500 | 1 | 0 | |
|
Garden Home SD |
1,472 | 1 | 1 | |
|
Sunset MHP |
1,400 | 2 | 0 | |
|
Blackhawk Estates LLC |
1,238 | 3 | 1 | |
|
South Barrington |
1,175 | 1 | 1 | |
|
Harbor Point Estates MHP Northbrook |
1,064 | 4 | 0 | |
|
Alpine Village MHP Lynwood |
970 | 3 | 0 | |
|
Spring Lakes MHP |
940 | 1 | 0 | |
|
Willoway Terrace MHP |
900 | 0 | 0 | |
|
Glenbrook SD |
822 | 0 | 0 | |
|
Forest View Forest View |
800 | 2 | 0 | |
|
IL American-Alpine Heights |
707 | 0 | 0 | |
|
Buckhorn Ranch Estates MHP Des Plaines |
702 | 0 | 0 | |
|
River Oaks Estates MHP Calumet City |
677 | 1 | 0 | |
|
Bedford Park Bedford Park |
602 | 0 | 0 | |
|
Franciscan Sisters of Chicago Lemont |
505 | 1 | 1 | |
|
Golf Golf |
497 | 0 | 0 | |
|
IL American-Moreland |
445 | 0 | 0 | |
|
LA Grange Estates MHP La Grange |
440 | 1 | 0 | |
|
Candlelight Village MHP |
420 | 1 | 1 | |
|
Des Plaines MHP |
405 | 2 | 1 | |
|
Paradise MHP |
390 | 0 | 0 | |
|
Oak Lane MHC Merrionette Park |
388 | 0 | 0 | |
|
Linway Estates MHP |
380 | 1 | 1 | |
|
Glen Eden Estates Homeowners Association |
312 | 3 | 0 | |
|
MC Cook Mccook |
280 | 0 | 0 | |
|
Lindentree Townhomes |
232 | 1 | 1 |
Non-community systems (260: schools, campgrounds, workplaces, restaurants)
These systems serve places people visit rather than homes.
Inactive systems (2,682, no longer operating or reporting)
Kept for the record and excluded from the county totals above. Browse inactive systems.
About this data
Totals cover active systems. Systems serving more than one county are counted in each county. EPA counts the rules a system was in violation of, not the individual violations; one rule can carry several.
Source: the U.S. EPA's Enforcement and Compliance History Online system (ECHO), which publishes the federal Safe Drinking Water Information System. EPA's terms and values are shown as published. The Illinois records are from EPA's data refresh of Oct 7, 2026; EPA refreshes this data quarterly, and states report to EPA with a lag of three to six months, so the newest violations may not appear yet. Retrieved from ECHO on Oct 11, 2026.