The California drought has brought the relationship between food production and water supplies into stark relief. Without adequate supplies of clean water, agriculture is impossible. Farmers know this all too well, but the average eater has no idea how much water goes into his or her diet. The hidden water, also called virtual water, behind food production makes up the majority of water that a person uses indirectly every day.

The water footprint method provides a sense of how much water is used for a given product or process. It is a total of all the water used to grow edible crops for humans and animals, to process food, and to clean up pollution caused by the food