The international trade in agricultural commodities at the same time constitutes a trade with water in virtual form. Water in external areas has been used to produce the food and feed items that are imported. The water footprint of a good or a service is the total amount of water, external and internal, that is required to produce it. The concept can be used to calculate and compare the strain on water resources resulting from different options. It can also be extended to provide water budgets for whole nations or continents.
The Swedish Research Council for Environment