Events are taking place around the world to mark World Water Day 2013.
This year's theme is about water cooperation - whether at the local scale in deciding how water should be apportioned, or at the international scale where resources cross borders.
Here are some facts the UN has released to spread awareness of the problem:
- Three-and-a-half planets would be needed to if the whole population was to attain the living standards of an average European.
- Almost 800 million people do not have access to clean water; almost 2.5 billion do not have access to adequate sanitation.
- Between six and eight million people die annually from the consequences of disasters and water-related diseases.