| County | Water System |
|---|
| Allegheny | Braddock Borough Water Authority |
| Allegheny | Harmar Township Municipal Authority |
| Allegheny | Monroeville Municipal Authority |
| Allegheny | Oakmont Borough Municipal Authority |
| Allegheny | Plum Borough Municipal Authority |
| Allegheny | Wilkinsburg-Penn Joint Water Authority |
| Armstrong | Gilpin Township Municipal Authority |
| Armstrong | Parks Township Municipal Authority |
| Bedford | Evitts Creek Water Company |
| Berks | Flying Hills Water System, Aqua Pennsylvania |
| Berks | Bern Township Municipal Authority |
| Berks | Reading Area Water Authority |
| Berks | Western Berks Water Authority |
| Berks | Shillington Municipal Authority |
| Berks | Wernersville Municipal Water Authority |
| Berks | West Reading Borough Water Authority |
| Berks | Boyertown Municipal Authority |
| Berks | Wyomissing Borough Water System |
| Berks | Ontelaunee Township Municipal Authority |
| Bucks | Bristol, Aqua Pennsylvania |
| Bucks | Bucks County Water & Sewer Authority |
| Bucks | Lower Bucks County Joint Municipal Authority |
| Bucks | Yardley, Pennsylvania American Water |
| Bucks | Bensalem, Aqua Pennsylvania |
| Bucks | Bristol Township, Water Department |
| Bucks | Warwick Township Water & Sewer Authority |
| Butler | Butler, Pennsylvania American Water |
| Chester | Uwchlan Township, Aqua Pennsylvania |
| Chester | Oxford Borough |
| Chester | Kennett Square Municipal Water Works |
| Chester | London Grove Township Municipal Authority |
| Clarion | Clarion, Pennsylvania American Water |
| Clarion | Farmington Township |
| Delaware | Chester Water Authority |
| Delaware | Bethel, United Water |
| Fayette | Pleasant Valley Water Authority |
| Fayette | Municipal Authority of Washington Township |
| Fayette | Connellsville, Pennsylvania American Water |
| Lawrence | Ellwood City, Pennsylvania American Water |
| Lawrence | New Wilmington Borough Water Department |
| Lebanon | Cornwall Borough Municipal Authority |
| Lebanon | Lebanon Water Authority |
| Lebanon | Fredericksburg Water Authority |
| Lebanon | West Lebanon Township Water Supply |
| Lebanon | Fort Indiantown Gap |
| Lehigh | Whitehall Township Authority |
| Mercer | Greenville Municipal Water Authority |
| Mercer | Shenango Valley, Aqua Pennsylvania |
| Montgomery | Hatboro, Aqua Pennsylvania |
| Montgomery | Horsham Water & Sewer Authority |
| Montgomery | North Penn Water Authority |
| Montgomery | Norristown, Pennsylvania American Water |
| Montgomery | Audubon Water Company |
| Montgomery | Aqua Pennsylvania Main Water System |
| Philadelphia | Philadelphia Water Department |
| Westmoreland | Municipal Authority of Westmoreland County |
| Westmoreland | New Kensington Municipal Authority |
| York | Glen Rock Water Authority |
| York | Stewartstown Borough Water Authority |
| York | Windsor Borough Water Authority |
| York | Dover Township Water system |
| York | New Freedom Borough Water Authority |
| York | Dallastown Water Authority |
| York | Red Lion Borough |
| York | York Water Company |
