A second plant, similar to Carlsbad, is being built in Huntington Beach, Calif., with the same 50-million-gallon-a-day capability. Currently there are 11 desalination plants in California, and 10 more are proposed. … For decades, we have been told it would one day turn oceans of salt water into fresh and quench the world’s thirst. But progress has been slow. That is now changing, as desalination is coming into play in many places around the world.