1. Pensacola, Fla. (Emerald Coast Water Utility). 
  2. Riverside, Calif. (City of Riverside Public Utilities). 
  3. Las Vegas (Las Vegas Valley Water District). 
  4. Riverside County, Calif. (Eastern Municipal Water District). 
  5. Reno (Truckee Meadows Water Authority). 
  6. Houston (City of Houston Public Works).
  7. Omaha (Metropolitan Utilities District).
  8. North Las Vegas (City of North Las Vegas Utilities Department). 
  9. San Diego (San Diego Water Department).
  10. Jacksonville, Fla. (JEA). 


Source: NBC News
Photo by  Wisconsin Department of Natural Resources