Southern California water agencies are kicking the tires on a very untraditional project: an undersea "water farm" that would park modular desalination pods more than 1,000 feet below the Pacific and quietly pipe drinking water back to shore.
OceanWell, a water-technology company working with several California agencies, says its "Water Farm 1" concept would tap natural deep-sea pressure to power reverse osmosis. The idea is to push large-scale freshwater production offshore and underwater, potentially delivering tens of millions of gallons per day while trimming some of the energy use and coastal impacts that have dogged traditional desalination plants. In a region where imported supplies are increasingly shaky, that is a tempting pitch.
How Water Farm 1 would work
Instead of forcing seawater at high pressure through membranes on land, OceanWell’s design lets physics do more of the work. At roughly 1,300 feet below the surface, hydrostatic pressure is intense enough that it can help drive the reverse-osmosis process, which in turn can shrink onshore pumping needs and overall energy demand.
According to OceanWell, a full Water Farm 1 field could scale to about 60 million gallons of potable water per day. Each modular pod is designed to produce up to one million gallons daily. The deeper placement is pitched as an efficiency upgrade, with the company claiming about a 40 percent cut in plant energy use compared with conventional shore-based desalination.
OceanWell also highlights its LifeSafe™ intake screens, which are meant to limit the entrainment of plankton and fish larvae, and deeper outfalls that are intended to better disperse concentrated brine. Together, those features are designed to address two of the main environmental complaints that routinely surface when new desal plants are proposed.
Pilot tests in a local reservoir
Before it can drop equipment into the ocean, OceanWell has been proving out the hardware closer to home. The company has been running a prototype pod inside the Las Virgenes Reservoir in a public-private pilot with the Las Virgenes Municipal Water District in the western San Fernando Valley.
As detailed by LVMWD, district staff lowered a pod into the reservoir and produced potable water in real time. The trial is meant to push the intake screens and filtration components in biologically active, somewhat messy conditions, rather than in a lab tank. Those reservoir results are being used to shape plans for onshore pipelines, water exchanges and permitting ahead of any open-ocean trials.
Why Carlsbad still looms large
Any new desalination idea in Southern California has to contend with the shadow of Carlsbad.
The Claude "Bud" Lewis Carlsbad desalination plant, which began commercial operations in 2015, remains the state’s most high-profile example of large-scale seawater desalination. It can produce roughly 54 million gallons per day, about 10 percent of San Diego County’s water supply, according to Poseidon Water.
The plant’s long permitting path and ongoing monitoring have laid bare the tradeoffs that come with that kind of coastal facility. A 2009 Regional Water Quality Control Board order required mitigation for intake impacts, according to the San Diego Regional Water Board. A 2019 peer-reviewed study later documented a salinity plume near the plant’s outfall that exceeded permitted levels, although it found limited measurable biological change in that already disturbed area, per the San Diego Regional Water Board and the journal Water.
Those kinds of findings are part of why subsea concepts like Water Farm 1 are trying to push intakes deeper and avoid the slug of dense brine that can pool on the seafloor when discharge is not well mixed.
Industry growth, emissions and expert caution
Desalination is not a niche experiment anymore. More than 20,000 plants operate worldwide, and the industry has been growing at about 7 percent annually since 2010. That rapid build-out is fueling a search for lower-impact designs instead of simply cloning existing coastal plants.
As reported by The Associated Press, the sector’s global emissions are estimated between roughly 500 million and 850 million tons of CO2-equivalent each year. That climate footprint has many experts arguing that any new desalination supply should be paired with aggressive recycling and conservation rather than replace them. Gregory Pierce, who directs water-resources work at UCLA, told The Associated Press that cost is likely to be the real tipping point for subsea systems like OceanWell’s.
Permitting, costs and what comes next
For now, Water Farm 1 remains an ambitious blueprint backed by some promising pilot data. OceanWell says it is moving from reservoir trials into ocean planning and is targeting a staged rollout around 2030, while participating agencies map out onshore infrastructure and water-exchange options, according to OceanWell.
"The freshwater future of the world is going to come from the ocean," CEO Robert Bergstrom told reporters, putting a clear stake in the ground. The company has also signaled that it plans to test its system off Nice, France, while its consortium partners continue feasibility studies and environmental reviews, according to The Associated Press.
If the pilots succeed, the permits materialize and the price per acre-foot can compete with recycling and conservation, subsea water farms could become one more tool in California’s drought toolkit. If those pieces do not fall into place, the concept is likely to stay where it is for now: an intriguing, high-tech niche rather than the region’s next big water lifeline.
