An underwater desalination plant off Norway cuts the energy cost of making drinking water by 40 to 50%

How an underwater desalination plant uses ocean pressure instead of pumps

Desalination means removing the salt from seawater to make it safe to drink. Most desalination plants sit on the coast and use powerful electric pumps to force seawater through a membrane, a thin filter that blocks salt, in a process called reverse osmosis. Running those pumps is normally the biggest cost. Flocean, a company based in Oslo, Norway, lowers the whole treatment unit onto the seabed, an underwater desalination plant off Mongstad, Norway, at 500 meters below the surface, where the weight of the ocean already pushes on the water close to the pressure a reverse osmosis membrane needs. The company states that moving a system 400 to 600 meters down lets it use the natural pressure of the ocean to cut cost and cut deployment time, the time it takes to build and start running a plant.

We're not making an incremental improvement, we're changing the fundamental economics of water.

Alexander Fuglesang, founder and chief executive of Flocean. Source 1.

Flocean reached first delivered water backed by 22.5 million dollars

Flocean announced 22.5 million dollars in extended Series A funding in November 2025, when the Mongstad unit had run for 12 months of testing, backed by Xylem, a water technology company, and 8 other investors. In June 2026, the unit produced its first drinkable water, up to 1 million liters a day, enough for about 6,000 households.

First water is more than a technical milestone.

Sivan Zamir, chief innovation and products officer at Xylem, an investor in Flocean, not a neutral outside voice. Source 2.

Scaling one seabed desalination unit into a full site

One Flocean unit produces about 1,000 cubic meters of desalinated water a day, the same 1 million liters converted into the volume measure the company uses for site scale. Flocean says a full site built from several units can produce between 5,000 and 50,000 cubic meters a day, a range GCN, a technology news outlet, confirms independently. Flocean states the achieved unit supplies about 6,000 households, while GCN separately estimates a comparably sized unit serves roughly 37,500 people. Dividing those 2 sourced numbers, a MAOWCE calculation neither source states, implies roughly 6 people per household counted, a check that the 2 estimates describe a similar amount of water rather than 2 different scales of unit. Two rivals, Waterise and OceanWell, are building similar pressure based systems for Jordan and California, Yahoo News reports.

The drinking water gap this seabed desalination pod could help close

The World Health Organization reports that 6,000,000,000 people used safely managed drinking water in 2022, its most complete category, meaning water available at home, free of contamination, whenever needed. Another 2,200,000,000 people did not, split between 1,500,000,000 people with only basic service and about 700,000,000 people below even that level. More than 4,000,000,000 people live in 135 low and middle income countries without safe drinking water, a figure Yahoo News attributes to the United Nations. No source examined for this article gives an independent benchmark for how much energy a conventional coastal desalination plant uses, so the 40 to 50% reduction Flocean reports stays a company comparison, worth remembering before signing a 15 to 25 year water contract under the build own operate model Flocean uses.