Four roads to fresh water

The United Nations says 1.8 billion people in the world use a source of drinking water that is faecally contaminated. Up to 2.4 billion lack access to basic sanitation (toilets and latrines). Charity WaterAid estimates that a child dies every two minutes as a result of diarrhoeal diseases caused by dirty water and poor sanitation. Engineering promises to change that with projects that range from smart pumps to devices that capture water from thin air, although effective change is likely to go beyond technological fixes.