More than one in 10 people in the world lack basic drinking water access, and by 2025, half of the world’s population will be living in water-stressed areas, which is why access to clean water is one of the National Academy of Engineering’s Grand Challenges. Engineers at Washington University in St. Louis have designed a novel membrane technology that purifies water while preventing biofouling, or buildup of bacteria and other harmful microorganisms that reduce the flow of water.