Turning air into water

Researchers at the Massachusetts Institute of Technology (MIT) have now demonstrated a novel approach: drawing water directly from the air. While the atmosphere is not considered a water source, it actually holds enormous quantities of vapour. If captured and condensed efficiently, this vapour could supply clean drinking water even in regions without rivers or groundwater.

The MIT team, led by Prof. Xuanhe Zhao, has developed an atmospheric water harvester that passively collects vapour across a wide range of humidity levels — even in desert conditions.

The device resembles a black, vertical panel, roughly the size of a window, filled with a special hydrogel. This material is engineered to swell as it absorbs vapour from the air, then contract again when the vapour is released. The collected vapour condenses on a cooled glass layer covering the panel and is funnelled out as drinkable water.

Field tests in Death Valley, California — one of the driest places in North America — showed that the system could still produce about 160 millilitres of water per day without requiring electricity, solar panels, or batteries.

Previous water-harvesting designs have often relied on embedding salts, such as lithium chloride, into hydrogels to boost water uptake. However, salts tended to leach into the harvested water, making it unsafe.

MIT’s breakthrough lies in adding glycerol, a stabiliser that keeps lithium salts from escaping into the water. Tests showed leakage levels below 0.06 ppm, well under the safety limit for groundwater set by the U.S. Geological Survey. This makes the harvested water safe for drinking without additional purification.

Although one panel produces a modest amount of water, the technology is designed for scalability. Arrays of vertical panels could be installed together, with researchers estimating that around eight panels, each measuring 3×6 feet, could meet the drinking-water needs of an average household.

Because the panels are compact and do not require an external power source, they can be deployed in resource-limited settings, such as schools, homes, and even remote desert communities. Water yields would naturally increase in humid climates, making the system adaptable to many environments.

As Zhao explains, the team views this as a proof of feasibility at scale: “We have built a meter-scale device that we hope to deploy in regions where even a solar cell is not very accessible. Now people can build it larger, or arrange multiple panels, to supply safe drinking water and achieve real impact.”

The study, published in Nature Water (2025), positions hydrogel-based water harvesting as a promising alternative to existing methods such as solar stills, fog nets, and metal-organic frameworks (MOFs). Unlike MOFs, which have limited water-carrying capacity, MIT’s hydrogel design both absorbs vapour efficiently and avoids contamination issues. This low-maintenance, passive system could help communities facing water scarcity.