Quenching San Diego’s Thirst With Seawater

From the Ocean to Your Faucet

Jill Cowan��Reporting from Carlsbad, Calif.

The plant, which opened in 2015, makes 50 million gallons of drinkable water every day. A massive pipe delivers water directly from the Pacific to tanks that work like Brita filters.

From the Ocean to Your Faucet

Jill Cowan��Reporting from Carlsbad, Calif.

Then, the water makes its way through a labyrinthine system of pipes where more impurities are removed, until there’s basically just salt left in the water. This gets the water ready for a high-tech reverse osmosis desalination process.

From the Ocean to Your Faucet

Jill Cowan��Reporting from Carlsbad, Calif.

Finally, the water is treated with fluoride and chlorine before it’s piped miles away to be added to the rest of the county’s water supply. The brine that’s left over gets mixed in with seawater and pumped back into the ocean.

From the Ocean to Your Faucet

Jill Cowan��Reporting from Carlsbad, Calif.

Right now, about 8 percent of the county’s water comes from the ocean. Critics call it some of the most expensive water that exists, and argue that operating the plant can harm the ocean ecosystem.

From the Ocean to Your Faucet

Jill Cowan��Reporting from Carlsbad, Calif.

Still, communities up the coast have taken notice — some are exploring seawater desalination. And another Poseidon Water plant is in the works for Huntington Beach.