Carlsbad Desalination Plant construction, as of January 2015. (San Diego County Water Authority)

As California heads into its fourth year of drought, more communities are looking to tap into the ocean for drinking water through the process of desalination, which removes salt from seawater to make it drinkable. Proponents see the ocean as a "drought-proof water supply," but desalination is expensive and critics say it's harmful to marine life.

David Jassby, assistant professor of chemical and environmental engineering at the University of California, Riverside, gives Here & Now's Jeremy Hobson an overview of desalination.

We then turn to Sandy Kerl of the San Diego County Water Authority, which is partnering with Poseidon Water on the Carlsbad Desalination Project in Carlsbad, California. When the project is completed this fall, it will provide more than 50 million gallons of drinking water a day to 112,000 homes in San Diego County and will be the largest desalination plant in the Western Hemisphere.

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