Catching up on a month’s backlog of reading, I came across an excellent piece on water shortages by Michael Specter, a former colleague of mine who writes on science and public health issues. It’s called “The Last Drop: Confronting the possibility of a global catastrophe,” in the 23 October issue of the New Yorker.

Specter opens the article by introducing us to Shoba, a young mother living with her husband and five children in Kesum Purbahari, a New Delhi slum, where women with buckets and pails line up at dawn to wait for a tanker truck carrying water. Everyone knows that to drink the thick, brown water from the community standpipe is to risk serious illness or even death. Some days, the tanker doesn’t come.

India, with 20% of global population, receives only 4% of the world’s annual supply of fresh water. India’s groundwater aquifers are quickly disappearing from over-pumping.

Even in prosperous neighborhoods of cities like Delhi and Mumbai, water is available for just a few hours a day — and often only as a brown and sludgy trickle — forcing millions of middle class Indians to stumble out of bed at three or four in the morning to turn on their taps.

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.”