Water footprints are a popular method for demonstrating the total amount of water needed to produce a variety of goods and services.
Introduced in 2002 by Arjen Hoekstra of the United Nations Educational, Scientific and Cultural Organization (UNESCO) as a comprehensive indicator of water use, the concept was refined and since 2009 has been promoted as a global calculation standard for water footprinting. This is maintained by the Water Footprint Network, an international network of governments, corporations, non-governmental organizations (NGOs) and United Nations bodies.
Water footprints have undoubtedly contributed to greater public awareness of the amount of water that is used to make everyday items. Typically a water footprint includes not only the water used to grow crops or other organic resources, but also that used in industrial processing and in transporting goods around the globe.
Water footprinting has also increased awareness of the concept of virtual water and its role in international trade. Thus, nations such as the United States of America, Argentina and Brazil are said to ‘export’ billions of liters of virtual water each year through the crops and other products they grow and trade, while other countries like Japan, Egypt and Italy ‘import’ billions of liters.
Some have argued that more account should be taken of ‘virtual water’ in international trade patterns. Others would like to see changes in the geography of production, so that the goods and services we consume worldwide can be produced with the smallest ‘water footprints’.