Humans need about 50 liters of water a day, of which only 2-3 liters are consumed as drinking water -- the rest is for cooking, bathing, and sanitation. The average American consumes 400-600 liters daily, more than anyone else, while European consumption is half that. India, Specter notes, promises its people -- but rarely provides -- 40 liters per day. (Unlike energy consumption, however, North America's waste of water has little or no relationship to shortages on the other side of the world.)

Nearly half the people in the world don't have the kind of clean water and sanitation that were available two thousand years ago to the citizens of ancient Rome. More than a billion people lack access to potable drinking water, and at least that many have never seen a toilet. Half the hospital beds on earth are occupied by people with an easily preventable waterborne disease.

The article examines India's emerging water crisis in considerable depth. In his conclusion, Specter cites Peter Gleick, who points out that per capita water consumption in the U.S. is now less than it was 25 years ago -- not because of conscious efforts to reduce water use, but because of changes in the U.S. economy and the introduction of more efficient ways of using water in both agriculture and industry.

"This is really good news," Gleick says. "Because it means we can do better. We don't need to run out of water. We just need to think more seriously about how we can avoid using it."