He concedes that the wastefulness (and water conservation) he chronicles has little or no effect on people in other watersheds because water is so difficult to ship.

But in the case of water, every man—or, at least, every water basin or region—is an island.

Long-term water availability is largely determined by the average conditions in a river basin, but it is often extreme events that cause acute water insecurity.

The Amazon Basin alone could see changes in biodiversity for 80 per cent of the region.

International river basins extend across the borders of 145 countries, and some rivers flow through several countries.