Many villagers in the deserts of Africa and India walk for hours each day to collect water, yet one-third of the planet’s fresh water is floating in the atmosphere rather than pooling in rivers and lakes. MIT engineers, inspired by the bumpy surface of a Namib Desert beetle that collects moisture from the air, have developed a mesh to harvest water from fog. The team refined a decades-old concept to find the optimal balance of water-attracting and -repelling surfaces on the mesh so that droplets coalesce and drip into a container. One square metre of the prototype material can produce about 1 litre of water a day.