Monday, October 4, 2010

What's the water footprint of the foods we grow?

I recently came across a book called The Green Blue Book: The Simple Water-Savings Guide to Everything in your Life, by Thomas M. Kostigen. The premise of the book is that "everything in your life" has a 'water footprint', which is made up of it's 'virtual water' content, or the total amount of water that it takes to make or grow something. Kostigan wrote the book to make readers aware of just how much water goes into the products that we use everyday so that we can make choices that will help us save water.

Although I think saving water is a really important fact of life, I'm not sure that knowing that the water footprint of a pound of beef (1500 gallons, according to The Green Blue Book is going to help encourage people to eat more soybeans (224 gallons per pound).

Determining the 'virtual water' content is pretty complicated for some things. The pound of beef listed above, for instance, takes into account the water required to grow the feed that the cow eats, the water the cow drinks, and the water required to process the beef. Kostigen doesn't go into the full details of how he came up with most of the numbers, such as the 39,000 gallon footprint for the average car.

I thought the book might list which fruits and vegetables required less water to grow, so that I could decide which ones I could plant that might survive drought conditions. After reading the book, I'm still not entirely sure that the figures he lists for fruits and vegetables JUST take into account the water required to grow them of whether something else is factored into his 'virtual water' number. Plus, although he does list that an apple, for example, has a virtual water footprint of 18.5 gallons per apple, you would have to try to figure out how many apples were on the average tree to come up with a number to represent how much water an apple tree would take. The same would hold true for the other fruits and vegetables he lists.

So, if you are trying to find a listing of waterwise fruits and vegetables to grow, The Green Blue Book probably isn't going to help much. But if you are curious about the water footprint of his book (42.8 gallons for the average book) or the computer you are reading this on (10,556 - 42,267 depending on the type of computer), you might want to give the book a read. Checking the book out of the library, like I did, will save the planet 42.8 more gallons of water.

1 comment:

  1. It is very important that people start thinking about the amount of water it takes to produce things and I appreciate the entry. The concept of your water footprint is key to that understanding.

    I do think knowing how much water it takes to produce a pound of beef versus a pound of vegetable protein is important to the argument. That in itself may not change one's behavior, but you can begin to see the difference made by skipping meat in one meal – and add that over time.

    What's not included in the water footprint (since its not necessarily a "use") is the impact of beef and other animal feedlot operations (Combined Animal Feeding Operations – CAFOs) to surface waters (local streams and the Chesapeake Bay) and groundwater from nutrients, sediment and pesticides. I guess that's another discussion altogether.


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