Virtual water was defined at the beginning of the 1990s by Professor J.A. Allan as „water embedded in commodities“ .
Virtual water is an important tool for calculating the real water consumption of a country.
Water consumption is the sum of domestic consumtion and virtual water import (import of products) minus virtual water export (export of products) of a country. The global volume of virtual water flows related to the international trade in commodities is 1.600 km3/yr.
About 80% of these virtual water flows relate to the trade in agricultural products, while the remainder is related to industrial products.