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Environment

Subsea desalination plant will turn Pacific Ocean into tap water

By Michael Franco
August 18, 2025
Subsea desalination plant will turn Pacific Ocean into tap water
Water, water everywhere and — soon — plenty of it to drink for Californians
Water, water everywhere and — soon — plenty of it to drink for Californians
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Water, water everywhere and — soon — plenty of it to drink for Californians
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Water, water everywhere and — soon — plenty of it to drink for Californians
The OceanWell facility will feed clean water from multiple pods through a pipeline back to shore
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The OceanWell facility will feed clean water from multiple pods through a pipeline back to shore

Dozens of water-harvesting pods are set to be deployed along the sea floor off the coast of California as the United States ramps up its first subsea desalination project. The effort is expected to produce 60 million gallons (227 million liters) of fresh water per day.

Thanks to increasing temperatures, California frequently struggles with maintaining an adequate freshwater supply. Extreme heat causes reservoirs to experience more rapid evaporation, snowmelt runoff is lower because there is simply less snow, the Colorado river is losing volume, and droughts are becoming more frequent and severe. Now, a new project aims to bring in fresh drinking water from the billions of gallons of water that lay off the state's west coast – the Pacific Ocean.

Water technology company OceanWell has just announced the launch of the Water Farm 1 (WF1) project in cooperation with Las Virgenes Municipal Water District (LVMWD), which manages fresh water for about 70,000 residents located in western Los Angeles County. Six additional California water agencies are also part of the effort.

The project will see roughly 60 of the company's modular subsea pods submerged to a depth of about 1,300 ft (400 m) and mounted to the ocean floor in Santa Monica Bay, off the coast of Malibu. The tremendous pressure at this depth forces water through the filters in each pod through reverse osmosis.

The filters are fine enough to not only block salt particles but also microplastics, bacteria, viruses, and PFAS, also known as "forever chemicals." The result is a million gallons of super-clean drinking water per pod per day That water is produced without mechanical action or disruption to marine life, and cuts energy usage by 40% compared to a traditional desalination plant, says OceanWell. The project aims to have the underwater facility pumping out 60 million gallons of clean water per day by 2030, and more beyond that.

The OceanWell facility will feed clean water from multiple pods through a pipeline back to shore
The OceanWell facility will feed clean water from multiple pods through a pipeline back to shore

"California, like much of the world, urgently needs a new source of water to replace dwindling supplies," said Robert Bergstrom, CEO of OceanWell. "Water Farm 1 shows how we can responsibly and economically harvest fresh water from the ocean by building infrastructure to withstand rapidly melting snowpack, increasing drought, more extreme atmospheric rivers, sea water intrusion, and overdrawn groundwater. Water Farm 1 is a critical milestone toward OceanWell's goal of adding one million acre-feet of new potable water to the global supply within a decade."

WF1 follows a pilot project OceanWell carried out with LVMWD in March 2025 that demonstrated the efficacy of the underwater filtration system.

As the project advances, several of the agencies in the consortium will conduct feasibility studies that examine ways to connect the WF1 water to existing infrastructure, while OceanWell's Tribal and Environmental Working Groups will continue to evaluate the results of the pilot pod. That will help the team configure the eventual size of the water harvesting field and ensure the project "reflects ecological best practices and community priorities," according to the company.

In addition to directly providing water to residents in LVMWD, the WF1 project is set to benefit other partners as well, such as the further afield city of Burbank.

"The City of Burbank does not have the ability to receive water directly from the Pacific Ocean," says Richard Wilson from Burbank Water and Power. "But with others in this consortium, we are working with the Metropolitan Water District of Southern California (MWD) to develop an innovative program to receive this water through an exchange. Burbank will pay for the delivery of OceanWell water to other partners in Water Farm. The water can then be exchanged between partners within the consortium by using water within MWD's system."

Source: OceanWell

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EnvironmentDesalinationCaliforniaWaterwater technologySalt-waterOcean
17 comments
Michael Franco
Michael Franco
Michael Franco has combined a masters degree in creative writing with a passion for peeking under the hood of life on Earth to write about the serious and silly sides of science and technology for years. He's published in Discovery Channel Magazine, Discover Magazine, CNET, HowToGeek, Lifehacker, and more. But by far, his favorite home so far is at New Atlas where he's allowed all the beakers and Bunsen burners he needs in which to mix his words. The mountains and beaches of central Portugal, where he now lives with his wife and two giant poodles, offer the perfect foil for way too much screen time.

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17 comments
Robt
This has nothing to do with warming anything. California’s population has exploded in the past fifteen / twenty years, and other than restarting a previously shuttered plant in 2015, they’ve built nothing of any size for decades. In 2022 a large, $1.4 billion plant was proposed and was turned down for ‘environmental’ reasons. That they’re finally going to do something is a minor miracle, but not everything should be ascribed to the climate. Sometimes simple math is the answer
Username
How long before the membrane gets clogged up with salt , plastic and other particulates? How do the filters get cleaned or replaced?
Ric
“Millions” of gallons of water is a very abstract figure with respect to the water needs of a community and the expense of running it. Some scale references as to how much water this actually is compared to drinking and farming and other usage per capita would be key, as well as scale comparisons to the Colorado river. Without scale of need, scale of cost, scale of alternative sources and their costs, all this other information is very difficult to evaluate.
Dave D
This is very dubious science. The problem is that pressure does exist at that depth it's well over 25 atmospheres but the pipeline needed to remove water from the depth counterbalances the pressure on the membrane and there's virtually no net pressure. Furthermore servicing a membrane that depth is difficult or impossible.
Neutrino23
The problem is agriculture. Over 80% of California water goes to agriculture. If agriculture were curtailed or more efficient then there would be plenty of water.
This is a clever technology. Water has to be pumped out of the device which lowers the pressure allowing more fresh water to replace that pumped out.
gimd
Maybe if they caught the water that is given for free and not release it all, SMH.
Bob Stuart
I don't see where the 40% energy savings is supposed to come from. After passing through the membrane, the pressure needed to get the fresh water to the surface is almost the same as the pressure going into the membrane, minus the density difference from salt to fresh in the water column.
TechGazer
David D beat me to it: the pressure deep down is useless for filtering on its own; you still need to power pumps to create a pressure _differential_. I don't see how the pressure deep down reduces that power consumption. It just adds expense of building and maintaining equipment at that depth. Maybe the company is using fast-talk about pressure to suck money from investors who don't know the difference between pressure and pressure differential.
Winterbiker
This has the potential to be cheaper and more reliable than the massive transcontinental pipelines (from the Great lakes or northern Canada) that have periodically been proposed.
Nelson
Climate change is making water shortages more prounced, so we desalinate, which uses a great deal of energy, and there we have a feedback loop for climate change.
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