An international team of engineers is a winner of the 2025 Gizmodo Science Fair for creating an atmospheric water harvesting device that could improve access to potable water in the most remote, arid regions of the world.
The question
Can we pull water out of thin air, even in the driest places on Earth?
The results
Engineers led by Xuanhe Zhao, a professor of mechanical engineering and civil and environmental engineering at the Massachusetts Institute of Technology (MIT), created an atmospheric water harvesting “window” (AWHW) that produces clean drinking water in extremely resource-limited conditions. It’s compact, completely self-sustainable, and only requires one input: sunlight.
“I invent soft materials to solve hard problems for the world,” Zhao told Gizmodo.
The core water-harvesting component of the AWHW is a hydrogel. This material is made from a hydrophilic polymer network and enriched with hygroscopic salts that readily absorb water from the air. It looks a bit like black bubble wrap, with small domed structures that swell when saturated, then shrink back down as they dry out. That swelling-shrinking transformation, inspired by origami, maximizes the material’s efficiency, Zhao said.
The next step was to design a chamber that captures the water collected by the hydrogel. They initially attempted to build a pyramid-shaped chamber, but this resulted in a large footprint for the device and sacrificed efficiency. So, Zhao asked his team, what would the simplest possible design look like?
The engineers ultimately sandwiched the hydrogel between two glass sheets coated with a cooling layer to create a black, window-sized vertical panel. When this panel is placed outside overnight, the hydrogel soaks up water vapor as temperatures drop and humidity rises. During the day, sunlight heats the gel and causes the captured water to evaporate, condense onto the glass, and then trickle down the panels and out through a tube for collection.
“This window-like design turns out to be very effective,” Zhao said.
The team tested their atmospheric water harvesting window (AWHW) for one week in Death Valley—the driest region of North America. The results, published in the journal Nature Water[1] in June, showed that this device is effective even in extremely low-humidity conditions. It worked across humidity levels ranging from 21 to 88% and produced water at rates of up to two-thirds of a cup (160 milliliters) per day. What’s more, this water was ready to drink immediately.
“We were so surprised by this,” “Will” Chang Liu, co-first author of the Death Valley study and former MIT postdoc, told Gizmodo. “It works pretty well at such low relative humidity.” This test also showed that the team’s vertical configuration is central to its efficiency, allowing the hydrogel panel to harvest water from both sides, Liu added.
“We are truly proud and excited about this work—and about the potential to help people most in need of safe drinking water,” Zhao said.
Why they did it
More than 2 billion people around the world lack access to clean drinking water, according to data from the World Health Organization and United Nations Children’s Fund[2]. Experts expect that figure to rise as population growth, economic development, poor resource management, and climate change drain Earth’s fresh water supply.
Developing a way to provide safe, manageable drinking water for people living in resource-limited regimes “is a grand challenge for the world,” Zhao said. Most people experiencing water scarcity lack access to terrestrial resources such as rivers, aquifers, and lakes, but there is a vast reserve of fresh water that’s present everywhere on Earth: the atmosphere.
“There is seven times more fresh water in air than in all the world’s rivers,” Zhao said. Harnessing even a small fraction of the millions of billions of gallons of water vapor in the atmosphere would go a long way toward improving access to clean water. Many people living in rural, water-stressed areas also lack reliable electricity and the resources necessary for technical equipment maintenance, Zhao explained. To overcome those gaps, an atmospheric water harvesting system needs to be simple, self-sustaining, and robust.
The hydrogel-based AWHW passively responds to the environment, no electricity required, Liu explained. This makes it especially well-suited for enhancing off-grid water security, she said.
“If you deploy this facility in those regimes, you can supply life-saving drinking water to people,” Zhao said.
Why they’re a winner
This isn’t the only team working to develop an atmospheric water harvesting device. Though other designs have proven effective[3], the AWHW improves on them in several key ways.
Designs made from metal-organic frameworks (MOFs) have emerged as some of the most efficient so far. These ultra-porous materials absorb water quickly and are effective in humidity levels as low as 14%, but they’re not very cost-effective, Liu said. What’s more, MOFs don’t swell or stretch when absorbing water, limiting their vapor-carrying capacity. Hydrogels, on the other hand, absorb water molecules into the volume of their materials, allowing them to hold more water. Additionally, their network of micro- and nanopores speeds up water absorption and release.
Not all hydrogels are created equal, however. Many designs—including MIT’s—use hydrogels enriched with salts to enhance their water-absorbing abilities. This often leads to salt leakage that contaminates harvested water. The AWHW overcomes this problem by adding glycol into the hydrogel. This liquid compound naturally stabilizes salt to prevent it from crystallizing and leaking into the water. For added protection, his hydrogel contains a microstructure that lacks nanoscale pores, further preventing salt leakage. As such, salt levels in water produced by the AWHW are significantly lower than those of other hydrogel-based designs.
“Without further purification, it’s directly drinkable,” Zhao said.
What’s next
Even though the Death Valley test showed that the AWHW works well in extremely arid conditions, Zhao and his team are still working to improve the device’s efficiency. Their ultimate goal is to produce enough water to supply entire households, even in desert climates. To that end, they are developing arrays of multiple panels that work together to further amplify water capture.
The team plans to test the device in other locations, including Morocco, where collaborator Youssef Habibi directs the Sustainable Materials Research Center at Mohammed VI Polytechnic University, Liu said. Now an assistant professor of mechanical engineering at the National University of Singapore, Liu also hopes to test the AWHW in Singapore’s humid, tropical climate. After that, the next steps are scaling up manufacturing, making this technology affordable for people, and getting the word out.
The team
The MIT team, led by Xuanhe Zhao, also consisted of “Will” Chang Liu, Xiao-Yun Yan, Shucong Li, and Bolei Deng. Non-MIT-affiliated contributors include Nicholas X. Fang of the University of Hong Kong, Hongshi Zhang of the University of Singapore, Youssef Habibi of Mohammed VI Polytechnic University in Morocco, and Shih-Chi Chen of the Chinese University of Hong Kong.
Click here to see all of the winners of the 2025 Gizmodo Science Fair.[4]
References
- ^ Nature Water (www.nature.com)
- ^ World Health Organization and United Nations Children’s Fund (www.unwater.org)
- ^ other designs have proven effective (gizmodo.com)
- ^ here (gizmodo.com)