TTHM (Total Trihalomethanes) violations in Illinois
355 active public water systems in Illinois had a TTHM (Total Trihalomethanes) violation in the past three years, 50 of them in the latest quarter of EPA's data. What TTHM (Total Trihalomethanes) is and why it matters.
Systems with a TTHM (Total Trihalomethanes) violation
Latest quarter first, then largest first| System | Serves | Status | Rules violated, 3 yr | Unresolved |
|---|---|---|---|---|
|
Wyoming Wyoming · Stark County |
1,300 | 4 | 1 | |
|
Good Shepherd Hospital Lake County |
1,290 | 8 | 2 | |
|
Fairfield Rural Waterworks--New Hope Fairfield · Wayne County |
1,285 | 4 | 1 | |
|
Hartford Hartford · Madison County |
1,260 | 2 | 0 | |
|
Aqua Illinois-Skyline (northern) Kane County |
1,200 | 2 | 0 | |
|
Chatsworth Chatsworth · Livingston County |
1,200 | 3 | 1 | |
|
ST Anne Saint Anne · Kankakee County |
1,200 | 4 | 0 | |
|
Windsor Windsor · Shelby County |
1,200 | 2 | 0 | |
|
New Berlin Sangamon County |
1,150 | 6 | 2 | |
|
Heartville Pwd Effingham County |
1,125 | 3 | 0 | |
|
Johnsburg No.2 McHenry County |
1,124 | 3 | 0 | |
|
Griggsville Pike County |
1,097 | 3 | 1 | |
|
Worden Worden · Madison County |
1,096 | 2 | 1 | |
|
Hamel Hamel · Madison County |
1,087 | 2 | 0 | |
|
Edinburg Edinburg · Christian County |
1,068 | 3 | 1 | |
|
Goreville Goreville · Johnson County |
1,068 | 3 | 0 | |
|
Thomasboro Thomasboro · Champaign County |
1,066 | 3 | 0 | |
|
Harbor Point Estates MHP Northbrook · Cook County |
1,064 | 4 | 0 | |
|
Shawneetown Shawneetown · Gallatin County |
1,054 | 2 | 1 | |
|
Coulterville Coulterville · Randolph County |
1,052 | 2 | 0 | |
|
Illiopolis Illiopolis · Sangamon County |
1,037 | 3 | 0 | |
|
Buncombe Water District Jackson County |
1,030 | 5 | 1 | |
|
EJ Water-Sangchris New Berlin · Sangamon County |
1,025 | 4 | 1 | |
|
Mounds Mounds · Pulaski County |
1,011 | 3 | 0 | |
|
Ridge Farm Ridge Farm · Vermilion County |
973 | 2 | 0 | |
|
Alpine Village MHP Lynwood · Cook County |
970 | 3 | 0 | |
|
Apple Creek Water Coop Morgan County |
968 | 3 | 0 | |
|
Percy Percy · Randolph County |
961 | 4 | 0 | |
|
Clay City Clay City · Clay County |
957 | 3 | 0 | |
|
Atkinson Atkinson · Henry County |
955 | 4 | 1 | |
|
Willow Lake Estates MHP Elgin · Kane County |
920 | 6 | 0 | |
|
Olympia School McLean County |
918 | 7 | 0 | |
|
Grand Valley Village MHP Springfield · Sangamon County |
912 | 4 | 1 | |
|
McClure-East Cape Pwd Alexander County |
910 | 2 | 0 | |
|
Argenta Argenta · Macon County |
900 | 4 | 1 | |
|
Bismarck Community Water District Vermilion County |
900 | 2 | 0 | |
|
Franklin Grove Franklin Grove · Lee County |
896 | 2 | 0 | |
|
Galatia Galatia · Saline County |
887 | 5 | 1 | |
|
Lawrence County Correctional Center Lawrence County |
870 | 5 | 2 | |
|
Dunfermline-St David Water Commission Fulton County |
850 | 1 | 0 | |
|
Albany Albany · Whiteside County |
846 | 7 | 0 | |
|
Cissna Park Cissna Park · Iroquois County |
846 | 2 | 0 | |
|
Exeter-Merritt Water Coop Scott County |
820 | 2 | 0 | |
|
Round Prairie Water Coop Springfield · Sangamon County |
813 | 1 | 0 | |
|
Blairsville Pwd Carterville · Williamson County |
807 | 6 | 1 | |
|
Elizabeth Elizabeth · Jo Daviess County |
802 | 1 | 0 | |
|
Forest View Forest View · Cook County |
800 | 2 | 0 | |
|
Willisville Willisville · Perry County |
799 | 2 | 0 | |
|
IL American-Walk UP Woods McHenry County |
775 | 3 | 0 | |
|
Fyre Lake Water Company Mercer County |
760 | 3 | 0 |
About this data
A system is counted once if any of its violations in the past three years involved TTHM (Total Trihalomethanes), including monitoring and reporting lapses. Rules violated and status in the table are for the whole system, not TTHM (Total Trihalomethanes) alone.
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.