How a deep-ocean desalination startup hopes to rewrite California's water future

An elephant standing full weight on a smartphone.That’s the pressure 1,400 feet underwater that a startup hopes to use to push seawater through ultrafine filters and make drinking water off the coast of Malibu — without much of the controversy that surrounds desalination.

Desalination plants are notoriously large electricity users.Some have natural gas pipelines running to them to fuel dedicated power plants.

The company OceanWell estimates its technology will cut that electricity use by up to 40%.Its goal is to anchor an array of units 4.5 miles offshore, at a cost of $500 million to $1 billion, to deliver 60 million gallons of water per day.

That’s enough for about 400,000 people.Prompted by severe water cutbacks four years ago, the Las Virgenes Municipal Water District has been working with Menlo Park-based OceanWell to develop a cheaper, less power-hungry way to turn saltwater into drinking water without sucking in tons of sea life.In a recent test at a local reservoir, it worked.“I’m really excited about it.

I think there’s a potential for this to be a game-changer,” said David Pedersen, the district’s general manager.“We’ve done what we can in the reservoir.

We really need to get in the ocean now.”OceanWell’s chief executive was equally pleased.“It went really, really well,” Robert Bergstrom said.

“It’s working.”The trial in Las Virgenes Reservoir near Westlake Village showed that the system prevented most plankton from being sucked in and killed, he said.Later this year, the company plans to test one of its “pods” suspended from a boat offshore.The next step would be to anchor one of the devices to the seafloor for a longer test.The goal is to build what Bergstrom calls Water Farm No.

1, an array of dozens of 40-foot-long pods.At a depth of about 1,400 feet, the pressure is more than 40 times greater than at the surface.

The technology harnesses that pressure to push seawater through reverse-osmosis membranes.Pur...