All known forms of life depend on water. Covering 71 per cent of the Earth's surface, water seems to be plentiful. But there are 1.2 billion people who currently live without a safe water supply, the amount of available drinking water is shrinking and the need for it is increasing relentlessly. While some regions are receiving too much rain, others are receiving too little. We are approaching a global water emergency. Julian Caldecott examines the vital role this fascinating substance plays on our planet and explores the historical, scientific, political and economic reasons behind the looming water crisis. He reveals where the water we use comes from, and at what social and environmental cost. This is an intriguing and sometimes unsettling portrait of the future of water in our changing world and what we can all do to make a difference.