Water Footprint
The water footprint is an indicator of freshwater use that looks at both direct and indirect water use of a consumer or producer. The water footprint of an individual, community or business is defined as the total volume of freshwater that is used to produce the goods and services consumed by the individual or community or produced by the business. Water use is measured in terms of water volumes consumed (evaporated) and/or polluted per unit of time. A water footprint can be calculated for a particular product, for any well-defined group of consumers (e.g. an individual, family, village, city, province, state or nation) or producers (e.g. a public organization, private enterprise or economic sector). The water footprint is a geographically explicit indicator, not only showing volumes of water use and pollution, but also the locations.
Content Table
History
The "virtual water" concept is marked by contention, but has received a growing recognition. Already in the early 1980s economists and agricultural economists in Israel noted that the country was irrational by exporting water intensive irrigated crops. Ten years later (1990) the London Group (SOAS - Water Research Unit) introduced the idea that it was sensible to "import" embedded water in crop commodities into water lacking political economies and in 1992 the term "virtual water" was introduced. The concept spread through other papers in the following years and in 1999 the UNESCO-IHE started to model and to quantify the virtual water flows all over the world.
The concept was refined and accounting methods were established in a series of publications: 'Water footprint of nations' report (Chapagain and Hoekstra, 2004), the Globalization of Water book (Hoekstra and Chapagain, 2008) and the Water Footprint Manual (Hoekstra et al., 2009). Cooperation between global leading institutions in the field has led to the establishment of the Water Footprint Network in 2008 that aims to coordinate efforts to further develop and disseminate knowledge on water footprint concepts, methods and tools.
Blue, green and grey water footprint
A water footprint consists of three components: the blue, green and grey water footprint.
The blue water footprint refers to the volume of surface and groundwater consumed as a result of the production of a good or service. Consumption refers to the volume of freshwater used and then evaporated or incorporated into a product. It also includes water abstracted from surface or groundwater in a catchment and returned to another catchment or the sea. It is the amount of water abstracted from ground- or surface water that does not return to the catchment from which it was withdrawn.
The green water footprint is the volume of rainwater consumed during the production process. This is particularly relevant for agricultural and forestry products (products based on crops or wood), where it refers to the total rainwater evapotranspiration (from fields and plantations) plus the water incorporated into the harvested crop or wood.
The grey water footprint of a product is an indicator of freshwater pollution that can be associated with the production of a product over its full supply chain. It is defined as the volume of freshwater that is required to assimilate the load of pollutants based on existing ambient water quality standards. It is calculated as the volume of water that is required to dilute pollutants to such an extent that the quality of the water remains above agreed water quality standards.
Water footprint of a product
The water footprint of a product (a commodity, good or service) is the total volume of freshwater used to produce the product, summed over the various steps of the production chain. The water footprint of a product refers not only to the total volume of water used; it also refers to where and when the water is used.
Water footprint of cotton consumption
Water footprint of coffee and tea production
Water footprint of a consumer
The water footprint of a consumer is defined as the total volume of freshwater consumed and polluted for the production of the goods and services consumed by the consumer. It is calculated by adding the direct water use by people and their indirect water use. The latter can be found by multiplying all goods and services consumed by their respective water footprint.
Water footprint of a business
The water footprint of a business – which can also be called alternatively corporate or organizational water footprint – is defined as the total volume of freshwater that is used directly and indirectly to run and support a business. The water footprint of a business consists of two components: the direct water use by the producer (for producing/manufacturing or for supporting activities) and the indirect water use (the water use in the producer’s supply chain). The 'water footprint of a business' is the same as the total 'water footprint of the business output products'.
Water footprint of national consumption
The water footprint of national consumption is defined as the total amount of fresh water that is used to produce the goods and services consumed by the inhabitants of the nation. The water footprint of national consumption can be assessed in two ways. The bottom-up approach is to consider the sum of all products consumed multiplied with their respective product water footprint. In the top-down approach, the water footprint of national consumption is calculated as the total use of domestic water resources plus the gross virtual-water import minus the gross virtual-water export.
References
Maite M. Aldaya, PhD. Twente Water Centre, University of Twente, The Netherlands
Chapagain, A. K. and Hoekstra, A. Y., 2004. Water Footprints of Nations. Value of Water-Research Report Series Nº. 16, UNESCO-IHE, Delft. The Netherlands.
Hoekstra, A.Y., (Ed.) 2003. Virtual water trade: Proceedings of the International Expert Meeting on Virtual Water Trade, Delft, The Netherlands, 12–13 December 2002, Value of Water Research Report Series No.12, UNESCO-IHE, Delft, the Netherlands.
Hoekstra, A.Y., Chapagain, A.K., 2008. Globalization of water: Sharing the planet’s freshwater resources. Blackwell Publishing. Oxford, UK.
Hoekstra, A.Y. Chapagain, A.K., Aldaya, M.M., Mekonnen, M.M., 2009. Water footprint manual: State of the art 2009. Water Footprint Network, Enschede, The Netherlands.
Hummel et al. 2006. Virtual Water Trade. Documentation of an International Expert Workshop. 3-4 July 2006, Institute for Social-Ecological Research, Frankfurt
WFN, 2010. Water Footprint Network. Available from: http://www.waterfootprint.org
