| City of Calgary, Alberta, Canada |
City of Charlottesville, Virginia |
| Cal Am Water-Baldwin Hills |
Cinco Municipal Utility District #1 |
| Cal Am Water-Larkfield District |
Cinco Municipal Utility District #8 |
| Cal Am Water-Monterey County Dist. |
City of Chicago, Illinois |
| Cal Am Water-Sacramento District |
Chicago Faucets |
| Cal Am Water-San Diego County Dist. |
Chicago Metropolitan Agency for Planning |
| Cal Am Water-Ventura County Dist. |
City of Chino, California |
| CA State Water Resources Control Board |
City of Chino Hills, California |
| CA Urban Water Conservation Council |
Cindy Dyballa Consulting |
| California Water Conservation Company |
City West Water, Ltd (Australia) |
| California Water Service Company |
Clean Water America Alliance |
| Cambria Community Services District |
Cobb County Water System |
| Canadian Water & Wastewater Association |
Joyce Coffee |
| Capital Regional District |
City of College Station, Texas |
| Caroma USA |
Colorado Springs Utilities |
| Cascade Water Alliance |
Colorado Water Conservation Board |
| Castleman & Sons Plumbing, Inc. |
Connecticut Water |
| CDM |
Conserve Florida Water Clearinghouse |
| City of Cedar Park, Texas |
City of Corpus Christi, Texas |
| Center for Water Efficient Landscaping, USU |
crmOrbit, Inc. |
| Central Basin Municipal Water District |
Cucamonga Valley Water District |
| Central Utah Water Conservancy District |
Cyber-Rain, Inc. |
| CH2M Hill |
Cypress Forest Public Utility District |