Desalination can turn seawater or brackish water into drinking water. California has four seawater desalination facilities, with more proposed. Poseidon Water’s facility in Carlsbad, the largest in the Western Hemisphere, provides about 12% of water used in San Diego County. Common concerns include cost, energy required and environmental impacts.
Desalination’s high cost mainly stems from its enormous use of fossil fuels, which also emit greenhouse gases. Pipes taking in water can kill marine organisms as they take in water, as well as the brine that is discharged back into the environment. Researchers in California and around the world are studying how to lower costs and improve desalination technology.