The world faces a water crisis — 4 powerful charts show how

The United Nations water conference starts tomorrow. Co-hosted by the Netherlands and Tajikistan, the three-day event will take place at UN headquarters in New York and will be the first such event in nearly half a century. During that time, a rising number of people around the world have gained access to safe water and sanitation (see ‘A tale of two halves’) — except in sub-Saharan Africa (see ‘The neglect of Africa’), where the numbers without safe drinking-water services are greater than they were in 2000. Globally, around 500 million people are compelled to use open defecation, and millions more rely on contaminated water supplies. Can this conference make a difference?