| City of Chino |
| City of Chino Hills |
| City of Colton |
| City of Corona |
| City of Norco |
| City of Ontario |
| City of Rialto |
| City of Riverside |
| City of San Bernardino |
| City of Upland |
| Cucamonga Valley Water District |
| Eastern Municipal Water District |
| Fontana Water Company |
|
| Home Gardens County Water District |
| Inland Empire Utilities Agency |
| Jurupa Community Services District |
| Monte Vista Water District |
| Riverside Highland Water Company |
| Rubidoux Community Service District |
| San Bernardino Valley Municipal Water District |
| Santa Ana River Water Company |
| West Valley Water District |
| Western Water |
