German scientists create a material that can pull drinking water from dry air—even at 18% humidity

Researchers have developed a highly porous material called CAU-10-H that can capture water vapour from the atmosphere even when relative humidity falls to just 18 percent. Combined with conductive carbon structures, the material can rapidly absorb and release water, opening up the possibility of decentralized freshwater systems in areas where conventional water sources are under growing pressure.

The technology could be particularly useful in regions such as the Mediterranean, where rising temperatures and declining rainfall are putting increasing pressure on freshwater supplies.

How does the material turn air into water?

CAU-10-H belongs to a class of materials known as metal-organic frameworks, or MOFs. These materials contain extremely porous structures with microscopic cavities that can trap molecules.


In the case of CAU-10-H, those tiny cavities allow the material to capture water molecules from humid air at room temperature. Once the material is heated to around 70 degrees Celsius, the stored water is released and can be collected as liquid water.

Laboratory tests showed that the composite can absorb as much as 0.17 grams of water per gram of material under dry conditions.

According to Kiel University, one kilogram of the composite could produce up to 1.8 litres of clean drinking water per day under suitable dry conditions.

The breakthrough works in very dry air

One of the most significant features of the material is the low humidity level at which it can operate.

Many atmospheric water-harvesting technologies work best when there is already considerable moisture in the air. CAU-10-H, however, can capture water when relative humidity is as low as 18 percent, a level approaching desert-like conditions.

That makes the material potentially relevant to places where conventional atmospheric water harvesting becomes difficult.

"The material's ability to work even in arid air is what makes it particularly attractive for producing drinking water in dry regions," said Lasse Wegner, lead author of the water-harvesting study.

Adding carbon makes the process faster

The Kiel team, led by Professor Norbert Stock, improved the material by integrating CAU-10-H with electrically conductive carbon structures.

The carbon component allows the material to be heated more efficiently, speeding up the process of releasing the captured water.

The composite can be heated using electricity or sunlight, and a complete capture-and-release cycle can take only a few hours rather than an entire day.

That faster cycle could be important for practical applications. Even if the amount of water captured during each cycle remains unchanged, a system capable of resetting several times a day could potentially produce more water over the same period.

It could also make cooling systems more efficient

The material's potential does not stop at producing drinking water.

Researchers also tested CAU-10-H as a refrigerant in adsorption-based cooling systems, which use repeated cycles of water vapour adsorption and release to create a cooling effect.

In tests, CAU-10-H delivered up to three times the cooling performance of silica gel, which is widely used in adsorption-based cooling applications.

A second study led by Kalle Mertin examined the material at a larger pilot scale and included a techno-economic assessment of its potential use in a full-scale cooling system.

Waste heat could power future systems

Another potential advantage is that CAU-10-H can be regenerated using relatively low-temperature heat.

That means future cooling systems using the material could potentially use waste heat generated by data centres, factories, bakeries and other industrial facilities instead of relying entirely on electricity.

Such systems could combine heat that would otherwise be discarded with cooling demand, potentially improving overall energy efficiency.

From a laboratory material to a real-world technology

CAU-10-H was first discovered at Kiel University around 15 years ago, while Professor Stock has studied its properties for more than two decades.

The latest research marks an important step because the material has now reached pilot-scale production, moving beyond the small batches typically produced for laboratory experiments.

Scaling up manufacturing will be critical if the technology is eventually to be deployed in real-world water-harvesting or cooling systems.

The research also arrives as interest in metal-organic frameworks continues to grow. The broader field received major recognition with the 2025 Nobel Prize in Chemistry, highlighting the potential of these highly porous materials.

For regions facing hotter temperatures, less rainfall and shrinking freshwater supplies, the ability to repeatedly pull water from air containing just 18 percent humidity could offer a potentially useful new source of freshwater—without relying on rivers, lakes or groundwater.