A small panel managed to extract a glassful of clean water from the bone-dry air of Death Valley in California, which suggests that the device could provide the vital resource to arid regions. The atmosphere over extremely dry land can hold large volumes of water, but extracting this in significant quantities without power is difficult. In the past, researchers have come up with innovative ways to tap into this reservoir, such as fog-catching nets made from simple mesh fabrics or spider silk-like artificial fibres, but they have struggled to make them work effectively in real-world conditions. Now, Xuanhe Zhao at the Massachusetts Institute of Technology and his colleagues have developed a power-free water-collecting device that is about 0.5 metres tall and 0.1 m across. It is comprised of a glass panel that contains an absorbent hydrogel, a jelly-like substance made from long-chain polymers, and lithium salts that can store water molecules.