The United Nations' most recent Intergovernmental Panel on Climate Change report paints a bleak picture for the world's water supply: Of the 7.8 billion people on Earth, about 4 billion do not have access to sufficiently clean water for at least a month every year. While several water purification schemes have been proposed, they consistently fail at some critical point—typically, they are not stable, big or hardy enough for real-world applications, according to researchers based at Technical Institute of Physics and Chemistry, Chinese Academy of Sciences and Xiamen University in China who may have cracked the problem.