For Parched Times, a New Water Calculus By Leslie Kaufman NYT

In my article about efforts by Levi Strauss & Company to adapt to climate change by reducing its water consumption, I mention the company’s estimate that each pair of 501 Levi’s jeans will consume 919 gallons of water during its life cycle. That includes everything from irrigating the cotton crop, to rinsing the jeans during the manufacturing process, to lots of home launderings.

But do those measurements go far enough?

It turns out that measuring water use is just as tricky as measuring carbon dioxide emissions. Yet the Water Footprint Network, a nonprofit group based in the Netherlands, has developed what it calls a gold standard for water use measurement and is urging that it be embraced by corporations, nations and individuals.

The method involves a calculation of “blue water” – that is, the amount of fresh water a company extracts from, say, a reservoir, a stream or an underground aquifer.

But the group also factors in categories that are less obvious. It counts “green water,” for example, or precipitation that falls but does not recharge groundwater or streams because it is absorbed for other purposes like growing cotton. And it measures “gray water,” or the water used to dilute pollutants in a manufacturing process so that they do not harm the local water quality when they are discharged from the factory.

Read the rest on The New York Times