Water has long been the object of political ambition and conflict. Recent history is full of leaders who tried to harness water to realize national dreams. Yet the people who most need water-farmers, rural villages, impoverished communities-are too often left, paradoxically, with desiccated fields, unfulfilled promises, and refugee status. It doesn't have to be this way, according to Fred Pearce. A veteran science news correspondent, Pearce...