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...