PHOTO: OCEANWELL
BY STAS MARGARONIS
The Los Angeles Times recently reported on a start-up company, OceanWell which plans to test a new desalination technology in deep water off the coast of Malibu, California in the latter part of 2026 after a successful trial in a California reservoir. The company says its deep-sea system, if proved viable, would transform salt water into pure drinking water at lower cost than a coastal desalination plant. 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.
The Times said that for nine months in 2025, OceanWell’s engineers tested a prototype desalination unit 50 feet underwater at Las Virgenes Reservoir. The trial in Las Virgenes Reservoir near Westlake Village in Los Angeles County showed that the system prevented most plankton from being sucked in and killed. The next step would be to anchor one of the devices to the seafloor for a longer test.
The goal is to build ‘Water Farm No. 1’, an array of dozens of 40-foot-long pods. At a depth of about 500 metres, the pressure is more than 40 times greater than at the surface. The technology harnesses that pressure to push seawater through reverse-osmosis membranes. Pure fresh water would be pumped to shore by pipeline.[1]
The 500-metre requirement suggests that the system will work well where the sea depth drops off dramatically as it does off the coast of California but less so on the shallower draft Atlantic coast where sea depth declines more gradually requiring power lines to be longer and more costly
Bergstrom says of the Malibu project: “We’re advancing Water Farm 1 in Santa Monica Bay, our first commercial-scale project, and studying how water produced offshore can be integrated into regional supply systems. The goal is to deliver fresh water to the region by 2031. We’re advancing Water Farm 1 with Las Virgenes and six other Southern California water agencies. The project is designed to deliver up to 60 million gallons of drinking water per day – enough to provide a secure base supply for 6.1 million Southern California residents … OceanWell would own and operate the offshore array and sell the water under contract, with initial estimates putting the cost between $2,000 and $3,000 per acre-foot. Full-scale costs will depend on the site, infrastructure, permitting, energy source and project scale.”
In a Q & A, OceanWell CEO Robert Bergstrom discussed the steps OceanWell is taking to perhaps finally create an economical and environmentally safe technology to build up fresh water supplies and head off the water shortages threatening California, Nevada and Arizona due to Colorado River fresh water shortfalls.
Margaronis: How well is the OceanWell desalination technology working and what are the potential markets?
Bergstrom:
The technology is definitely working, and we’re encouraged by what we’ve seen so far.
With Las Virgenes Municipal Water District, we completed a year-long pilot in the Las Virgenes Reservoir. The system produced high-quality fresh water, ran with 93% uptime during an endurance test, and performed in line with our engineering model.
That matters because OceanWell is not trying to make a slightly better version of conventional desalination; we want to make big improvements. We’re looking to provide a huge reduction in power use and, at the same time, eliminate environmental problems of traditional desalination systems. Our subsea water farms use natural ocean pressure at depth to help drive reverse osmosis. At roughly 500 meters, the ocean is already providing the pressure that a traditional plant needs to create with energy-intensive pumps. By harnessing that natural pressure, our system can reduce energy use by up to 40% compared with average traditional onshore desalination plants. The subsea designed also avoids the need for a large industrial plant onshore and is designed to reduce environmental impacts through a lower-salinity outfall and a low-velocity intake system that helps protect marine life.
The next step is proving it in the ocean. We’re advancing Water Farm 1 in Santa Monica Bay, our first commercial-scale project, and studying how water produced offshore can be integrated into regional supply systems. The goal is to deliver fresh water to the region by 2031. We’re advancing Water Farm 1 with Las Virgenes and six other Southern California water agencies. The project is designed to deliver up to 60 million gallons of drinking water per day – enough to provide a secure base supply for 6.1 million Southern California residents… OceanWell would own and operate the offshore array and sell the water under contract, with initial estimates putting the cost between $2,000 and $3,000 per acre-foot. Full-scale costs will depend on the site, infrastructure, permitting, energy source and project scale.
The clearest markets are water-stressed coastal regions that need new, drought-resilient supply and have access to deep water, from Southern California to island communities like Hawaii. The model can also support inland areas through regional water exchanges, including the Colorado River Basin, by adding new supply to coastal systems and easing pressure on existing imported sources. Internationally, we’ve already begun expanding, with our first European deployment now underway in Nice, France.
Internationally, we’ve signed an MOU with Eau d’Azur, the public utility serving the 51 municipalities of the Nice Metropolis, for our first deployment in France. We’re also backed by Kubota Corporation and have advanced to the semifinalists stage in the XPRIZE Water Scarcity competition.
Margaronis How cost-efficient is the technology?
Bergstrom:
The biggest cost advantage is energy.
Traditional desalination uses high-pressure pumps to force seawater through reverse-osmosis membranes onshore. We use natural ocean pressure at depth to help do that work, which we estimate can reduce energy use by up to 40%.
The system is also modular. Each pod is designed to produce up to one million gallons of fresh water per day, so a water farm can scale by adding pods rather than building one large onshore plant upfront. Onshore plants have a fixed production limit; OceanWell’s modular concept can easily scale as demand increases.
Margaronis: Can the desal technology run on renewable energy?
Bergstrom:
Yes. OceanWell’s water farms can be powered by renewable energy through the grid, with the long-term goal of operating on 100% renewable power. And since the system also uses about 40% less energy, this approach favors renewable sources. This is in keeping with OceanWell’s environment-first philosophy that informed the whole design.
Margaronis: Does the need to be proximate to a 500-meter depth pose challenges in delivering the water from the seabed to land-based communities? What are the challenges to transfer the fresh water to shore? A pipeline? Tanker ships?
Bergstrom:
OceanWell’s system requires two connections between the shore and the offshore water farm: an umbilical power cable that powers the pumps in the system, and a freshwater pipeline that carries the produced water back to shore. It is helpful for a site to be relatively close to a port with access to the types of vessels needed to lay the pipelines and install the pods, such as those used by the offshore energy industry. For OceanWell’s project in Nice, for example, the company plans to use vessels from Marseille, which has an established offshore energy network.
Existing pipelines could potentially be used, depending on their condition and what they previously carried. Because pipelines used for drinking water need to be clean, OceanWell’s working assumption is that it will install its own freshwater pipeline at each site.
Freshwater pipelines are relatively standard and readily available. The umbilical power cables are more specialized, take longer to manufacture and cost more per mile. OceanWell’s preference for sites where deep water is close to shore is therefore driven more by the required length of the power cable than by the freshwater pipeline.
If the distance from the water farm to shore becomes too long, OceanWell may need to step up the power supplied to the system to account for power losses over distance. This would add infrastructure costs. The need to install these connections is also why OceanWell conducts detailed site surveys at every location. The surveys allow the company to plan the routes for the power cable and freshwater pipeline back to shore.
Margaronis: I also read that OceanWell has discussed the possibility of a collaboration between Arizona and LAMWD about providing additional desal water to LA and having LA share its Colorado River allocation with Arizona. Could you explain how that will work? I note the following summary: “In June 2026, Arizona, California, Nevada, and the Bureau of Reclamation signed a Memorandum of Understanding to explore a framework for interstate exchanges. This initiative allows the Southwest states to collaboratively finance water supply solutions—such as the Claude “Bud” Lewis Carlsbad Desalination Plant—providing participating agencies with water during peak demands or shortages.”
Bergstrom:
A water exchange works when multiple regions receive their water from a common source. If Southern California gains access to a new, reliable freshwater supply from OceanWell’s offshore desalination, it can reduce its reliance on Colorado River allocations. That would allow more Colorado River water to remain available for Arizona and Nevada, effectively delivering water without constructing a new interstate pipeline.
Under the model OceanWell is exploring, desalinated water would be delivered into the Metropolitan Water District of Southern California’s system. Arizona and Nevada could help fund the new Pacific water supply, production and exchange process in return for corresponding benefits within the Colorado River system.
The June 2026 memorandum of understanding referenced in the question is separate from OceanWell and Water Farm 1. Neither OceanWell nor Las Virgenes is a signatory.
Margaronis: What is the cost per acre foot that OceanWell is projecting to deliver water?
Bergstrom:
The current preliminary estimate for Water Farm 1 is between $2,000 and $3,000 per acre-foot. The $3,000 figure is therefore the upper end of the estimated range, not a fixed or contracted price. The range will be refined as the project’s feasibility and design work advances and will ultimately depend on factors including inflation before construction, the site, infrastructure, permitting, energy requirements and project scale. This water supply will provide only 10-15% of the total supply to 6.1 million people, so any price impact on customers’ utility bills will be relatively small. The role of this supply is to provide these millions of people with a base supply of climate-resilient water, defined as supplies on which “variation in rainfall and temperature has little or no influence”.
Margaronis: The California Coastal Commission objected to the Carlsbad desal project in part because of the salt plume that desal generates. Can you tell me how OceanWell addresses this plume issue and also the threat of fish and marine life being sucked in?
Bergstrom:
OceanWell’s LifeSafe™ system is designed to avoid the concentrated brine discharge and marine-life disruption associated with traditional desalination. OceanWell’s outfall salinity is only one-quarter the salinity increase of standard desalination plants. This much lower salinity concentration … is dispersed through risers into deep-water currents, where it readily diffuses to ambient ocean salinity. The riser height is designed around conditions at each site to support rapid diffusion within meters of the discharge point and prevent the brine from settling or being drawn back into the pods.
Seawater enters through fine, 0.5-millimeter wedge-wire screens at low velocity. The screens are twice as fine as the recommendation in the 2019 California Ocean Plan Amendment and the intake velocity is three times slower than the relevant EPA recommendation, helping avoid the entrainment and impingement of larger organisms. The design intent is for microscopic organisms to pass safely past the membranes and return to the ocean without experiencing a pressure change.
OceanWell successfully tested its LifeSafe circulation system during its year-long pilot in the highly biologically active Las Virgenes Reservoir—conditions more demanding than those expected in the deep ocean. The system demonstrated safe operation for aquatic life while maintaining consistent performance.
Margaronis: The issue of renewable solar energy powering desal has been applied in the Middle East and I wonder what information we have about renewables reducing desal costs compared to fossil fuels. I note your response as follows: “Yes. OceanWell’s water farms can be powered by renewable energy through the grid, with the long-term goal of operating on 100% renewable power. And since the system also uses about 40% less energy … This is in keeping with OceanWell’s environment-first philosophy that informed the whole design.”
Bergstrom:
OceanWell’s energy requirements are 40% less than those of the average traditional onshore desalination systems. OceanWell’s water farms can be powered through the grid or by renewable sources, with the long-term goal of operating on 100% renewable power as renewable energy infrastructure is developed.
Margaronis: Has anyone considered linking desal plants to offshore wind farms?
Bergstrom:
While we would happily welcome such a co-location, water is expensive to transport, so it would require a large volume of water at the wind farm’s shore crossing, and we have not yet seen both factors coincide.
FOOTNOTE
[1] https://www.latimes.com/environment/story/2026-06-02/california-desalination-tech-oceanwell-testing