Researchers from Stanford University and MIT have developed a longer-lasting hydrogel that can pull moisture from the air and turn it into drinkable water using sunlight. The work could help people in dry regions where traditional water sources are limited. WHO and UNICEF reported in 2025 that one in four people globally, or 2.1 billion people, still lacked access to safely managed drinking water.

Researchers from Stanford University and MIT have developed a longer-lasting hydrogel that can pull moisture from the air and turn it into drinkable water using sunlight.

The work could help people in dry regions where traditional water sources are limited. WHO and UNICEF reported in 2025 that one in four people globally, or 2.1 billion people, still lacked access to safely managed drinking water.

The material is a sponge-like mix of lithium chloride and polyacrylamide. Lithium chloride is a highly absorbent salt, while polyacrylamide is a polymer also used in products such as diapers.

The hydrogel absorbs water vapor from the air. When sunlight heats the material, it releases the trapped moisture as vapor, which can then be condensed into drinkable water.

Earlier field testing in Chile’s Atacama Desert used a panel of the material mounted on a black-painted aluminum sheet. The sheet absorbed heat from the sun and helped the hydrogel release collected water.

The material worked in earlier tests, but it only lasted about 30 fill and release cycles before breaking down. That created both cost and safety concerns because degraded salt or polymer could enter the condenser and affect water quality.

After four years of lab work, the team found that the metal surface holding the hydrogel was causing the problem. The metal released ions that formed damaging radicals inside the gel, which then broke down the polymer chains.

The researchers fixed the issue by adding a commercial anti-corrosion coating to the metal. That coating blocked the ions from reaching the hydrogel.

With the coating in place, the hydrogel stayed stable for more than eight months in stress testing and lasted for more than 190 water harvesting cycles.

The study was published in Nature Communications on May 7.

The paper said the coating strategy allowed stable moisture absorption and release for more than 190 cycles over 96 days. It also said the approach could create a path toward producing water from air for less than $0.01 per liter.

Carlos Diaz-Marin, assistant professor of energy science and engineering at Stanford’s Doerr School of Sustainability and co-lead author of the study, said the improvement could eventually bring the cost of water produced this way to about one cent per liter.

That would be about 1% of the cost of bottled water and close to the cost of tap water in some US cities, Stanford reported.

The current design can produce up to two liters of water per day using a thin layer of material spread across a panel roughly the size of a bath towel. Stanford said that is around the amount generally needed per person per day for basic health during emergencies.

Diaz-Marin wants to increase output to five liters per day. That could make the system more useful for rural communities in dry inland regions where desalination is not practical.

The technology is not ready for large-scale deployment yet, but the researchers are working to improve efficiency and reduce cost.

The hydrogel approach is one of several emerging technologies designed to pull water from the air. Other researchers are also studying metal-organic frameworks, which can capture water at very low humidity levels.

The new work shows that durability may be just as important as water capture itself. Without a longer-lasting material, water harvesting from air would remain too expensive and unreliable for practical use.

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