Most Americans get their drinking water from fresh water sources like lakes and rivers, or from groundwater drawn from wells.
But freshwater supplies are falling at a time when demand is rising. Now a massive effort is underway in southern California to make drinking water out of something there's plenty of: Sea water.
San Diego water authorities are planning the largest desalination plant in the Western Hemisphere. The project's developer closed financing for the nearly $1 billion project just last week.
With more is Alison St. John, a reporter for PBS in San Diego.