TTHM (Total Trihalomethanes) violations in Pennsylvania
535 active public water systems in Pennsylvania had a TTHM (Total Trihalomethanes) violation in the past three years, 39 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 |
|---|---|---|---|---|
|
East Donegal Lancaster County |
4,048 | 3 | 0 | |
|
Shohola Falls Trails End Sys#2 Pike County |
3,933 | 3 | 2 | |
|
Hegins Hubley Authority Schuylkill County |
3,870 | 2 | 0 | |
|
Mountain Water Assn Fayette County |
3,856 | 6 | 1 | |
|
Masontown Muni Water Works Fayette County |
3,841 | 4 | 0 | |
|
Tobyhanna Army Depot Monroe County |
3,800 | 4 | 0 | |
|
Cooper Twp Municipal Auth Clearfield County |
3,700 | 3 | 0 | |
|
Middlesex Twp Muni Auth Cumberland County |
3,527 | 2 | 0 | |
|
Borough of Cornwall Lebanon County |
3,343 | 3 | 0 | |
|
Lykens Boro Auth Dauphin County |
3,220 | 6 | 0 | |
|
Procter&gamble Paper Products Wyoming County |
3,200 | 1 | 0 | |
|
Esasd North Campus Pike County |
3,175 | 1 | 0 | |
|
Coudersport Boro Authority Potter County |
3,166 | 9 | 1 | |
|
East Taylor Muni Auth Cambria County |
3,152 | 6 | 1 | |
|
Aspinwall Boro Water Dept Allegheny County |
3,151 | 3 | 1 | |
|
Tower City Borough Authority Schuylkill County |
3,150 | 3 | 0 | |
|
Midland Boro Muni Auth Beaver County |
3,100 | 7 | 1 | |
|
Bcwsa New Hope Bucks County |
3,017 | 2 | 0 | |
|
Orwigsburg Municipal Water Wks Schuylkill County |
3,000 | 2 | 0 | |
|
Seven Springs Muni Auth Somerset County |
3,000 | 2 | 0 | |
|
Ford City Muni Water Works Armstrong County |
2,991 | 2 | 0 | |
|
Northwestern Lancaster CO Auth Lancaster County |
2,968 | 1 | 0 | |
|
Reynoldsville Water Auth Jefferson County |
2,908 | 4 | 0 | |
|
North Coventry Water System Chester County |
2,907 | 3 | 0 | |
|
Sci Dallas Luzerne County |
2,900 | 5 | 0 | |
|
Honey Brook Boro Water Chester County |
2,892 | 5 | 0 | |
|
Nesquehoning Boro Water Auth Carbon County |
2,850 | 3 | 1 | |
|
Hughesville Borough Water Auth Lycoming County |
2,800 | 7 | 0 | |
|
Milesburg Borough Water Auth Centre County |
2,750 | 4 | 2 | |
|
Ohioville Boro Muni Auth Beaver County |
2,750 | 6 | 0 | |
|
Youngstown Boro Muni Auth Westmoreland County |
2,730 | 1 | 0 | |
|
Montgomery Water Authority Lycoming County |
2,700 | 3 | 0 | |
|
Upmc Western Psychiatric Inst Allegheny County |
2,645 | 3 | 1 | |
|
Bentleyville Muni Auth Washington County |
2,600 | 4 | 1 | |
|
Meyersdale Muni Auth Somerset County |
2,566 | 5 | 0 | |
|
State Correctional Inst Cumberland County |
2,522 | 4 | 0 | |
|
Cresson Twp Muni Auth Cambria County |
2,500 | 1 | 0 | |
|
Lehigh Carbon Community Colleg Lehigh County |
2,500 | 1 | 0 | |
|
Milford Water Authority Pike County |
2,420 | 3 | 0 | |
|
Johnsonburg Municipal Auth Elk County |
2,413 | 6 | 1 | |
|
Lehigh Career & Technical Inst Lehigh County |
2,400 | 1 | 0 | |
|
Misericordia University Luzerne County |
2,400 | 7 | 2 | |
|
Reynolds Water Company Mercer County |
2,370 | 4 | 1 | |
|
Duncansville Muni Water Auth Blair County |
2,350 | 5 | 1 | |
|
Mercersburg Muni Water Auth Franklin County |
2,350 | 7 | 1 | |
|
Coatesville Veterans Adm Hosp Chester County |
2,000 | 3 | 0 | |
|
General McLane Schools Erie County |
2,000 | 2 | 0 | |
|
McConnellsburg Boro Muni Auth Fulton County |
2,000 | 9 | 0 | |
|
West Kittanning Muni Auth Armstrong County |
2,000 | 1 | 0 | |
|
Evans City Borough Butler County |
1,990 | 1 | 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 Pennsylvania 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.