A few related points
The term ‘virtual water’, first introduced by Allan (1998), refers to the volume of water used to produce traded crops. By importing food a country ‘saves’ the amount of water it would have required to produce it on its own soil. Thus, international food trade can have important impacts on how and where water is used.
We“eat”between 2,000 and 5,000 liters of water per day—depending on our diet. Insignificant in comparison are the amounts of water each person uses for drinking (between 2 to 5 liters per day) and for washing, sanitation and other household needs (between 50 and 200 liters per day).
It takes between 500 to 4,000 liters of water to grow one kilogram of wheat,but upto 10,000 liters to produce one kilogram of grain-fed beef (fig.1 ).In the United States of America an average meat diet contains an estimated 5,400 liters of water per person per day, while vegetarian diet contains 2,600 liters. If every person adopted a typical U.S. diet, approximately 75% more water would be needed for food production(WorldWater Council,VirtualWater Trade,March 2004).
Japan—the world’s biggest grain importer—would require an additional 30 billion cubic meters of water to grow the annually imported cereals on its soil. By importing grain, Egypt—a highly water stressed country—saved some 8.5 billion cubic meters of irrigation water—one sixth of the annual releases from the High Aswan Dam.
The idea of food trade as an answer to water shortages is appealing. But firmly established political, social and economic interests in agricultural trade will limit the potential of this option. Under the prevailing political and economic climate, it is unlikely that food trade alone will solve problems of water scarcity in the near term.