The Water Footprint Network, its partners, and scientists of the University of Twente in the Netherlands have conducted foundational research into a Global Water Footprint Standard. Of particular importance in this regard is the Footprint Assessment Manual.

The diagrams and information used here by Science for the People are adapted from:
Hoekstra, A.Y. (2008) The water footprint of food, In: Förare, J. (ed.) Water for food, The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (Formas), Stockholm, Sweden, pp. 49-60.

Illustrated data also available at The Water Footprint Network and at VirtualWaterEU