Saving water through global trade

The most direct positive effect of virtual water trade is the water savings it generates in the countries or the regions that import the products. This effect has been widely discussed in virtual water studies since the nineties ( Allan, 1999b ). These national water savings are equal to the import volumes multiplied by the volumes of water that would have been required to produce the commodities domestically. However, virtual water trade does not only generate water savings for importing countries, it also means water ‘losses’ for the exporting countries (in the sense that the water cannot be used anymore for other purposes in the exporting countries). The global net effect of virtual water trade between two nations will depend on the actual water volume used in the exporting country in comparison to the water volume that would have been required to produce a commodity in the importing country. There will be net water saving, if the trade is from countries with relatively high water productivity (i.e. commodities have a low virtual water content) to countries with low water productivity (commodities with a high virtual water content). There can be net additional consumption of water if the transfer is from low to high productive sites. The saving can also be realised with transfer of products from low to high productive periods by storage of food, which can be a more efficient and more environmentally friendly way of bridging the dry periods than building large dams for temporary water storage ( Renault, 2003 ).