Calculating Water Use, Direct and Indirect
Henry Fountain
New York Times
04/19/2010
How much water do you use every day?
Your household water meter only tells part of the story — what was directly used for washing, cooking and other tasks. But what about the water that was used to grow the food you ate for dinner? Or to manufacture the book you bought or the gasoline your car burned?
Researchers at Carnegie Mellon University have estimated this kind of direct and indirect water use — not for households, but for American industries. Their goal was to create a tool for better assessing the impact on water use of decisions made up and down the industrial supply chain, just as one might assess cost or carbon footprint.
Chris Hendrickson, a professor of civil and environmental engineering; Michael Blackhurst, a graduate student; and Jordi Sels i Vidal, a visiting researcher, used water data from the United States Geological Survey (from 2000) and applied an economic model to estimate direct and indirect use in paint manufacturing, fiber and yarn making, grain farming and about 420 other industrial sectors, big and small. Their findings are reported in Environmental Science and Technology.
