Virtual Water
If you thirst for new ideas, try this:Virtual water is the amount of water that is embedded in food or other products needed for its production. For example, to produce one kilogram of wheat we need about 1,000 litres of water, i.e. the virtual water of this kilogram of wheat is 1,000 litres. For meat, we need about five to ten times more.
The per capita consumption of virtual water contained in our diets varies according to the type of diets, from 1m3/day for a survival diet, to 2.6m3/day for a vegetarian diet and over 5m3 for a USA style meat based diet.
(Via WorldChanging.)