Science and technology for water purification in the coming decades

Water under pressure Over a billion people around the world lack access to safe drinking water and over two billion have little or no sanitation. Do we have the resources — and the will — to provide the water to support a booming population? This issue of Nature (see introduction, p. 269 and Editorial, p. 253) tackles the science, economics and politics of the global water crisis. Climate scientists say that unreliable rains and drier summer soils will become more common: Quirin Schiermeier reports on water strategies for a drier world. The pressure is on farmers to get maximum crop yields with minimum water use. As Emma Marris reports, the collaboration between plant breeders, agronomists and geneticists to that end has been far from smooth. As the population of India grows, the demand for water keeps rising. Daemon Fairless investigates an ambitious plan to redistribute the country's water supplies by linking rivers in a vast canal network. Jamie Bartram says it is time to improve the global targets for access to water and sanitation to make them relevant to all. In most countries, crop irrigation accounts for most freshwater use — more than drinking water and domestic consumption — but water use in energy production is catching up fast. Mike Hightower and Suzanne Pierce describe the measures being developed to economize on water use in the energy sector. The need for research into water purification is pressing. In an extensive Review Article, Mark Shannon et al. highlight the developing technologies that — it is hoped — can provide our drinking water in the decades ahead. Water is (almost) everywhere, yet physicists still trade theory and counter theory to explain its structure: Phil Ball explains. And Books & Arts looks at a documentary on water security, and at art inspired by water's surprising patterns. Go to http://www.nature.com/news/specials/water/index.html for the on-line start-page.