Professor John Anthony Allan (University of London), the Inventor of the Virtual Water concept, was awarded the 2008 Stockholm Water Prize last week.
I had never heard of this concept but it's very interesting. It is a method of calculating the amount of water spent in the production of certain products, particularly food products.
Did you know, for instance, that it takes 140 liters of water to produce a cup of coffee? (this is a calculation based on the water that was consumed to grow, produce, package and ship the coffee beans). That is the same amount of water that is consumed daily by a person in England by drinking, bathing, cooking, etc.
Take a look at these links:
http://www.reuters.com/article/inDepthNews/idUSL1850227220080319