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 |
|---|---|---|---|---|
|
Alhambra Alhambra · Madison County |
755 | 1 | 0 | |
|
Moro Pwd Madison County |
750 | 4 | 1 | |
|
Brownstown Brownstown · Fayette County |
740 | 2 | 1 | |
|
Oakland Oakland · Coles County |
739 | 3 | 0 | |
|
Shawnee Valley Pwd Union County |
738 | 1 | 0 | |
|
IL American-Bahl Water Company Jo Daviess County |
700 | 7 | 1 | |
|
Westfield Westfield · Clark County |
678 | 6 | 2 | |
|
Cambridge Courts MHP Northbrook · Lake County |
658 | 2 | 0 | |
|
Shops of Kildeer Lake County |
650 | 7 | 2 | |
|
Vergennes Vergennes · Jackson County |
648 | 3 | 0 | |
|
Coffeen Coffeen · Montgomery County |
647 | 3 | 1 | |
|
Cordova Cordova · Rock Island County |
640 | 3 | 0 | |
|
Ashmore Ashmore · Coles County |
637 | 8 | 0 | |
|
Keyesport Keyesport · Clinton County |
625 | 2 | 0 | |
|
Wayne School DuPage County |
625 | 4 | 0 | |
|
Union-York Water District Clark County |
600 | 3 | 1 | |
|
Fairview Fairview · Fulton County |
588 | 2 | 0 | |
|
ST Francisville Saint Francisville · Lawrence County |
583 | 7 | 0 | |
|
Sawyerville Sawyerville · Macoupin County |
578 | 4 | 1 | |
|
Cullom Cullom · Livingston County |
563 | 1 | 0 | |
|
Sidell Sidell · Vermilion County |
557 | 1 | 0 | |
|
Baldwin Baldwin · Randolph County |
547 | 1 | 0 | |
|
Dorchester Dorchester · Macoupin County |
540 | 2 | 0 | |
|
Farina Farina · Fayette County |
540 | 1 | 0 | |
|
Wilsonville Wilsonville · Macoupin County |
536 | 3 | 1 | |
|
Choate MHC Anna · Union County |
533 | 3 | 2 | |
|
Decatur Mhp, LLC Decatur · Macon County |
500 | 3 | 1 | |
|
Lake Shannon Essex · Kankakee County |
500 | 5 | 0 | |
|
Mount Auburn Mount Auburn · Christian County |
480 | 2 | 0 | |
|
Towanda Towanda · McLean County |
480 | 3 | 2 | |
|
Meadowbrook MH Community, LLC Belleville · St. Clair County |
463 | 4 | 1 | |
|
Dalton City Dalton City · Moultrie County |
454 | 1 | 0 | |
|
Alexander Water District Morgan County |
442 | 2 | 0 | |
|
Arenzville Arenzville · Cass County |
419 | 1 | 0 | |
|
Blm GW Mhp, LLC Bloomington · McLean County |
390 | 6 | 2 | |
|
Forge at the Lake Madison County |
387 | 6 | 0 | |
|
Henderson Henderson · Knox County |
375 | 5 | 3 | |
|
Sunny Hill Estates Subdivision Henry County |
375 | 1 | 0 | |
|
EJ Water-Dewey Champaign County |
350 | 2 | 1 | |
|
New Piasa Chautauqua PWS Jersey County |
335 | 4 | 2 | |
|
Easton Easton · Mason County |
325 | 2 | 0 | |
|
Woodland Woodland · Iroquois County |
319 | 4 | 1 | |
|
Fsh Water Commission Smithton · St. Clair County |
313 | 2 | 0 | |
|
Lee Lee · Lee County |
313 | 2 | 0 | |
|
Little York Little York · Warren County |
304 | 3 | 0 | |
|
Ilpo Redwood MHP LLC Pontiac · Livingston County |
300 | 1 | 0 | |
|
Loraine Loraine · Adams County |
300 | 5 | 3 | |
|
Northwestern Medicine Woodstock Hospital McHenry County |
300 | 2 | 1 | |
|
Olivet Pwd Vermilion County |
300 | 1 | 0 | |
|
Stepan Company Will County |
300 | 5 | 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.