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 |
|---|---|---|---|---|
|
Joliet Joliet · Will County |
160,000 | 4 | 0 | |
|
Berwyn Berwyn · Cook County |
57,250 | 3 | 0 | |
|
Glenview Glenview · Cook County |
47,856 | 2 | 0 | |
|
Country Club Hills Country Club Hills · Cook County |
16,500 | 2 | 1 | |
|
Westchester Westchester · Cook County |
16,241 | 2 | 0 | |
|
River Grove River Grove · Cook County |
10,282 | 1 | 0 | |
|
Osf ST Francis Hospital Peoria County |
10,000 | 4 | 1 | |
|
Volo Volo · Lake County |
6,629 | 2 | 0 | |
|
Aqua Illinois-Candlewick Dvn Boone County |
6,426 | 1 | 1 | |
|
Northshore University Evanston Cook County |
6,300 | 4 | 1 | |
|
Fayette Water Company Fayette County |
5,608 | 5 | 0 | |
|
Millstone Pwd Pope County |
5,565 | 5 | 1 | |
|
Posen Posen · Cook County |
5,331 | 3 | 1 | |
|
U of I Chicago Medical Center Cook County |
5,000 | 4 | 1 | |
|
Lebanon Lebanon · St. Clair County |
4,714 | 2 | 0 | |
|
Saline Valley Conservancy District Eldorado · Saline County |
3,921 | 2 | 0 | |
|
Red Bud Red Bud · Randolph County |
3,804 | 1 | 0 | |
|
Gillespie Macoupin County |
3,737 | 8 | 3 | |
|
Northshore Univ Glenbrook Cook County |
3,200 | 4 | 1 | |
|
Dixmoor Dixmoor · Cook County |
2,973 | 5 | 4 | |
|
Menard Correctional Center Randolph County |
2,950 | 4 | 2 | |
|
Highland Park Hospital Lake County |
2,800 | 5 | 2 | |
|
Northshore University Skokie Cook County |
2,500 | 4 | 1 | |
|
Waubonsee Community College Kane County |
2,000 | 7 | 0 | |
|
Mitchellsville Pwd Saline County |
1,970 | 3 | 0 | |
|
Bluford Bluford · Jefferson County |
1,880 | 1 | 0 | |
|
Grantfork Grantfork · Madison County |
1,766 | 5 | 2 | |
|
Sheridan Correctional Center LaSalle County |
1,670 | 2 | 2 | |
|
Cerro Gordo Cerro Gordo · Piatt County |
1,350 | 2 | 1 | |
|
Assumption Assumption · Christian County |
1,315 | 4 | 2 | |
|
Lake Williamson Christian Center Macoupin County |
1,250 | 4 | 0 | |
|
Albers Albers · Clinton County |
1,231 | 3 | 2 | |
|
Swedish Covenant Hospital Cook County |
1,200 | 6 | 1 | |
|
Mechanicsburg-Buffalo Water Commission Sangamon County |
1,170 | 7 | 2 | |
|
Royalton Royalton · Franklin County |
1,118 | 6 | 0 | |
|
Franciscan Health Olympia Fields Cook County |
1,050 | 2 | 0 | |
|
Camargo Camargo · Douglas County |
750 | 1 | 0 | |
|
Vermont Vermont · Fulton County |
738 | 4 | 0 | |
|
JW Marriot Hotel Cook County |
700 | 4 | 2 | |
|
Pocahontas Pocahontas · Bond County |
697 | 5 | 4 | |
|
River Oaks Estates MHP Calumet City · Cook County |
677 | 1 | 0 | |
|
Golconda Golconda · Pope County |
630 | 2 | 0 | |
|
Beach MHP Zion · Lake County |
624 | 1 | 0 | |
|
Damiansville Damiansville · Clinton County |
602 | 6 | 2 | |
|
College View Subdivision Lockport · Will County |
570 | 2 | 1 | |
|
Beecher City Beecher City · Effingham County |
500 | 6 | 1 | |
|
Marianjoy Rehab Hospital DuPage County |
500 | 3 | 0 | |
|
Sunnyland Subdivision Joliet · Will County |
300 | 4 | 2 | |
|
Uaw Senior Citizens Center Pekin · Tazewell County |
240 | 4 | 4 | |
|
Kane County Div of Transport Kane County |
40 | 4 | 1 |
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.