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 |
|---|---|---|---|---|
|
Wilkinsburg-Penn JT Water Auth Allegheny County |
125,000 | 3 | 0 | |
|
ST Marys Area Water Auth Elk County |
19,588 | 4 | 0 | |
|
E Stroudsburg Boro Water Dept Monroe County |
13,000 | 2 | 0 | |
|
City of Lock Haven Water Dept Clinton County |
8,450 | 6 | 1 | |
|
North East Township Water Erie County |
5,848 | 4 | 0 | |
|
Hilltown Twp Water&sewer Auth Bucks County |
5,770 | 5 | 0 | |
|
Tarentum Boro Water Dept Allegheny County |
4,927 | 6 | 0 | |
|
Fawn Frazer JT Water Auth Allegheny County |
4,650 | 3 | 0 | |
|
New Wilmington Boro Water Dept Lawrence County |
4,500 | 3 | 0 | |
|
Southwestern Cambria Cnty Auth Cambria County |
4,400 | 7 | 0 | |
|
Pleasant Valley Water Auth Fayette County |
3,630 | 3 | 1 | |
|
Nanty Glo Water Auth Cambria County |
3,152 | 6 | 1 | |
|
Gallitzin Boro Water Auth Cambria County |
3,130 | 8 | 0 | |
|
Sandycreek Twp Waterworks Venango County |
2,417 | 2 | 0 | |
|
Hastings Muni Auth Cambria County |
2,100 | 3 | 1 | |
|
East Deer Twp Water Dept Allegheny County |
2,000 | 3 | 1 | |
|
Sandy Township Clearfield County |
1,828 | 4 | 0 | |
|
Ridgway Twp Water Auth Elk County |
1,763 | 2 | 0 | |
|
Shamokin Dam Borough Snyder County |
1,700 | 3 | 0 | |
|
Blacklick Valley Muni Auth Cambria County |
1,650 | 4 | 1 | |
|
Township of Springdale Allegheny County |
1,600 | 4 | 1 | |
|
South Buffalo Twp Muni Auth Armstrong County |
1,230 | 3 | 1 | |
|
Galeton Borough Authority Potter County |
1,200 | 5 | 1 | |
|
Bloomfield Boro Water Auth Perry County |
1,170 | 2 | 0 | |
|
Polk Center Venango County |
1,058 | 13 | 0 | |
|
Thomas Jefferson Univ Hospital Philadelphia County |
1,000 | 4 | 0 | |
|
Huston Twp Muni Auth Clearfield County |
960 | 2 | 0 | |
|
Landis Homes Lancaster County |
850 | 2 | 0 | |
|
Donegal Township Washington County |
820 | 7 | 1 | |
|
Marion Twp Water Sys Beaver County |
700 | 1 | 0 | |
|
Mapleton Muni Water Auth Huntingdon County |
570 | 6 | 1 | |
|
Icmsa Cherry Tree Indiana County |
375 | 4 | 1 | |
|
Woodhaven Mobile Home Park Erie County |
350 | 12 | 4 | |
|
Api Technologies Mfg Erie County |
300 | 2 | 0 | |
|
Ross Elementary School Luzerne County |
130 | 5 | 1 | |
|
Gillett MHC Bradford County |
100 | 10 | 1 | |
|
Richmond Center YMCA Berks County |
100 | 1 | 0 | |
|
Mehoopany Twp Municipal Auth Wyoming County |
85 | 6 | 2 | |
|
Barr Area Municipal Authority Cambria County |
60 | 2 | 0 | |
|
Pittsburgh Water & Sewer Auth Allegheny County |
520,000 | 3 | 0 | |
|
City of Lancaster Lancaster County |
120,000 | 2 | 0 | |
|
Lca Allentown Division Lehigh County |
118,000 | 3 | 0 | |
|
Lebanon Water Auth Lebanon County |
57,000 | 2 | 0 | |
|
Cranberry Twp Wtp Butler County |
42,000 | 3 | 0 | |
|
Southwestern PA Water Auth Greene County |
40,200 | 3 | 0 | |
|
Newtown Artesian Water CO Bucks County |
38,500 | 1 | 0 | |
|
Moon Twp Muni Auth Allegheny County |
38,000 | 4 | 0 | |
|
Northampton Bucks CO Mun Auth Bucks County |
36,750 | 4 | 0 | |
|
Plum Boro Muni Auth Allegheny County |
27,500 | 2 | 0 | |
|
Auth of Boro of Charleroi Washington County |
27,000 | 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 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.