Desalination Is Having a Moment

The need for desalination has long been clear in water-scarce regions of the planet. But with roughly a quarter of the global population now facing extreme water stress and drought conditions only projected to intensify, the technology is becoming an increasingly necessary tool for survival in a wider array of geographies.

Typically, scaling up desalination infrastructure has meant building costly, energy-intensive coastal plants that rely on a process called reverse osmosis, which involves pushing seawater through semi-permeable membranes that block salt and other contaminants, leaving only fresh water behind. Now, however, a number of startups are attempting to rework that model, with solutions that range from subsea facilities to portable desalination devices for individuals and families.

They could find potential customers across the globe. Many countries in the Middle East — including Saudi Arabia, Israel, Bahrain, Kuwait, and Qatar — rely on desalination for the bulk of their municipal water. Meanwhile, drought-prone regions from Australia to the Caribbean and California have also turned to the technology to shore up supply. But as the Iran war has underscored, this vital infrastructure is increasingly being treated as a military target, exposing a significant vulnerability in a resource relied upon by hundreds of millions.

One more resilient alternative is to move the plants underwater — making them more difficult to target while also harnessing subsurface pressure to do some of the energy-intensive work of desalination.

“I came up with the idea of using natural pressure to run the process,” Robert Bergstrom, a veteran of the water industry and CEO of the desalination startup OceanWell, told me. That meant “putting the membranes in a place where it’s already 800 pounds [of pressure] per square inch” — e.g. inside pods on the ocean floor, each capable of producing 1 million gallons of freshwater daily. By using the natural pressure of the ocean to drive the reverse osmosis process, this approach cuts energy use by about 40%, he said, thus slashing the system’s largest operating cost: electricity.

OceanWell’s design maintains a lower internal pressure within each pod than the surrounding environment, causing seawater to flow passively inside and push through membranes — just like on land, but without the high-pressure pumps. Compact pumps inside the pods then push the freshwater up a pipeline to the shore, while the resulting brine dissipates in the deep ocean.

The method also helps solve another problem with conventional desalination: environmental impact. Today’s facilities typically produce a more concentrated brine that they discharge at the ocean’s surface, which is more disruptive to marine ecosystems. The plants also frequently cause damage to organisms large and small by either trapping them against water intake screens or pulling them into the plant itself. That’s been a big sticking point when it comes to permitting these facilities, especially in California where the startup is based. OceanWell’s system, Bergstrom said, is able to filter out larger organisms while allowing microscopic ones to pass through the pods and return to the ocean.

The company began a trial last year in partnership with Las Virgenes Municipal Water District in southern California, testing its system in a freshwater reservoir full of marine life to verify its safety. Next it will test its pods in the ocean before undertaking a pilot in a to-be-determined location — California, Hawaii, and Nice in southern France are all contenders. If all goes according to plan, OceanWell will follow that up with a full-fledged commercial system targeted for 2030.

But it’s not the only startup pursuing underwater desalination — or even the one with the most aggressive timeline. Two years ago, Norwegian startup Flocean spun out of the subsea pump specialist FSubsea with a similar technical approach and a plan to deploy its first commercial system off Norway’s western coast this year. Flocean has already logged over a year of testing in the deep ocean, a stage OceanWell has yet to reach.

OceanWell thinks it can differentiate itself by meeting the unusually stringent permitting required in California. “If we can get it done in California, then the rest of the world will follow,” Bergstrom told me, meaning more resilient, more energy-efficient freshwater infrastructure for all. But it’s a high bar. The last major effort to build a desalination facility in the state led to a long-running fight that ended in 2022 with a rejection. Over 100 groups opposed the facility proposed for Orange County, citing risks to marine life, as well as high energy requirements and costs, with many arguing that alternatives — such as conservation and wastewater treatment — would be more superior options.

Megan Mauter, an associate professor of civil engineering at Stanford, thinks the groups may have a point, especially when it comes to overall system costs. The high capex of desalination can be hard to justify in California, she told me, since the state doesn’t need it 100% of the time, only in bad drought years. For example, just a few weeks ago, The Wall Street Journal reported that San Diego County’s desalination plant, by far the largest in California, now has a surplus of desalinated water that it’s looking to sell to drought-ridden Western states such as Nevada and Arizona.

And while desalination startups purport to cut overall system costs, she has her doubts about that. “The energy savings that they’re going to get are offset by some pretty high increased costs of the other elements of their plant designs,” Mauter told me. “In a subsea system, you’ve got these unproven and not mass-manufactured skids. You’ve got subsea installation, and then mooring it, and putting in pipelines that you’ve got to maintain all the way to land. You’ve got to convey water back to shore, which takes energy, and you are going to have significantly higher maintenance burdens in an open ocean environment.”

Despite her reservations, she certainly sees the appeal of non-traditional water sources, “even at costs that would have been totally infeasible a decade ago.” Municipal planners are staring down a future of worsening drought at the same time that states in the Colorado River basin remain locked in contentious negotiations over water rights, debating how to allocate cuts as river flows have declined nearly 20% since 2000. California’s narrow continental shelf also makes it an ideal environment for subsea desalination, as having deep water close to shore allows the system to harness pressure depths while minimizing the length of the pipeline needed to transport freshwater to land. Norway is also favored in this way.

“I don’t know whether the cost gaps can be solved, but I bet that the technology gaps could be solved,” Mauter told me.

Ultimately, she thinks the binding constraint is likely to be regulatory rather than technical. “Permitting is going to be a nightmare unless something fundamentally changes,” she said. Bergstrom told me that OceanWell is currently working with the California State Water Resources Control Board to revise its rules that govern desalination facilities in order to account for new technologies, though how long that process will take is anyone’s guess.

There’s one idea emerging in this ecosystem that largely sidesteps the regulatory constraints that control our land and seas. The startup Vital Lyfe has developed a portable desalination unit roughly the size of a small cooler that allows individuals and households to produce freshwater on demand with reverse osmosis — effectively decentralizing the desalination industry in the same way that the startup’s founders, former SpaceX engineers, helped decentralize internet infrastructure with Starlink.

“We’ve seen this paradigm shift coming out of Starlink that traditional, large, centralized, systems are very expensive,” Vital Lyfe CEO Jon Criss told me. “They’re hard to deploy and hard to scale up when you really need them.”

After raising a $24 million seed round in December, the startup launched its first product a few weeks ago, which retails for $750. At that price point, it’s a great deal for sailors spending days or weeks at sea, but likely too expensive for the individuals in remote communities far from water infrastructure that might need it most. Criss’s goal is to quickly iterate on this first product to bring more affordable models to the market in short order.

Portable desalination devices aren’t anything new in and of themselves — they’ve been used in military, maritime, and humanitarian scenarios for decades. The startup’s breakthrough, Criss explained, is more about manufacturing efficiency than technology. “We went all the way back, looked at why every component was designed and how to redesign it for high rate manufacturing. So we were able to substantially drop the cost of ownership and operation of these things.”

You’ll soon find Vital Lyfe’s product in big box retail stores, Criss said, though he also aims to partner with large-scale desalination facilities and utilities to help boost their output. Either way, the startup is already generating buzz — it’s seen significant inbound interest as of late, as the inherent resilience of its small system stands in sharp contrast to the vulnerability of conventional desalination infrastructure now being targeted in the Middle East.

The company is scaling up to meet the moment, building out a facility in Los Angeles county that Criss said will eventually produce 120 portable units per hour. He’s aiming to start production by summer’s end, ramping to full capacity by October. “Within the next three years we plan to account for about 10% of total membrane production at Vital Lyfe alone,” he told me, referring specifically to the production for the desalination industry.

The future of the industry, of course, could look like any combination of all of these approaches — portable devices, conventional plants on land, and modular systems at sea. What seems certain is that as the globe continues to heat up, so will desalination tech.