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Encyclopedia > Virtual water

Virtual water (also known as embedded water, embodied water, or hidden water) refers to the water used in the production of a good or service. For instance, it takes 1,300 cubic meters of water on average to produce one metric tonne of wheat. The precise volume can be more or less depending on climatic conditions and agricultural practice. Hoekstra and Chapagain (2007) have defined the virtual-water content of a product (a commodity, good or service) as "the volume of freshwater used to produce the product, measured at the place where the product was actually produced". It refers to the sum of the water use in the various steps of the production chain. As Tony Allan (2005) stated: "The water is said to be virtual because once the wheat is grown, the real water used to grow it is no longer actually contained in the wheat. The concept of virtual water helps us realize how much water is needed to produce different goods and services. In semi-arid and arid areas, knowing the virtual water value of a good or service can be useful towards determining how best to use the scarce water available." This article or section does not cite its references or sources. ...


Virtual Water

It is essential to recognize that virtual water adds up. To produce 1 kilogram of wheat about 1000 liters of water are needed, but for beef about 15 times as much is required. The majority of the water that we consume is embedded in our food. Below there is a listing of the various average amounts of virtual water in food. This data was published through UNESCO-IHE Institute for Water Education [1]: The UNESCO-IHE Institute for Water Education is an international institute for water education that is established in 2003. ...

Agricultural Products

  • the production of 1 kg wheat costs 1,300 L water
  • the production of 1 kg broken rice costs 3,400 L water
  • the production of 1 kg eggs costs 3,300 L water
  • the production of 1 kg beef costs 15,000 L water
  • the production of 1 cotton shirt of 300 gram costs 2,500 L water

Species T. aestivum T. boeoticum T. compactum T. dicoccoides T. dicoccon T. durum T. monococcum T. spelta T. sphaerococcum T. timopheevii References:   ITIS 42236 2002-09-22 For the indie rock group see: Wheat (band). ... For other uses, see Rice (disambiguation). ... An egg is a body consisting of an ovum surrounded by layers of membranes and an outer casing of some type, which acts to nourish and protect a developing embryo. ... For other uses, see Beef (disambiguation). ...

Household Products

Not only is there virtual water in food, but it is located in various other products that the everyday person uses. The figures below were taken from another report published through UNESCO-IHE titled The Water Footprint of Cotton Consumption.[2] The UNESCO-IHE Institute for Water Education is an international institute for water education that is established in 2003. ...

  • Jeans (1000g) there is 10,850 liters of embedded water
  • Diaper (75g) there is 810 liters of embedded water
  • Bed Sheet (900g) there is 9,750 of embedded water

Industrial Products

Industrial goods also contain embedded water. One needs to understand how internal water resources are being used to produce cars, bicycles, teacups, and the like - particularly because industry usually uses only blue water for production (though rainwater harvesting is becoming more common). On average, a 1.1 tonne passenger car has about 400,000 liters of water embedded in it. This fact is compiled from several different resources including the Chapagain report and the Australian Food & Grocery 2003.

The three colors of a product’s virtual-water content

The virtual-water content of a product consists of three components, namely a green, blue and gray component. [3]

The ‘green’ virtual-water content of a product is the volume of rainwater that evaporated during the production process. This is mainly relevant for agricultural products, where it refers to the total rainwater evaporation from the field during the growing period of the crop (including transpiration by the plants and other forms of evaporation).

The ‘blue’ virtual-water content of a product is the volume of surface water or groundwater that evaporated as a result of the production of the product. In the case of crop production, the blue water content of a crop is defined as the sum of the evaporation of irrigation water from the field and the evaporation of water from irrigation canals and artificial storage reservoirs (although for practical reasons the latter component has been left out from our studies). In the cases of industrial production and domestic water supply, the blue water content of the product or service is equal to the part of the water withdrawn from ground or surface water that evaporates and thus does not return to the system where it came from.

The ‘gray’ virtual-water content of a product is the volume of water that becomes polluted during its production. This can be quantified by calculating the volume of water required to dilute pollutants emitted to the natural water system during its production process to such an extent that the quality of the ambient water remains beyond agreed water quality standards.

The distinction between green and blue water originates from Falkenmark (2003). It is relevant to know the ratio of green to blue water use, because the impacts on the hydrological cycle are different. Both the green and blue components in the total virtual-water content of a product refer to evaporation. The gray component in the total virtual-water content of a product refers to the volume of polluted water. Evaporated water and polluted water have in common that they are both ‘lost’, i.e. in first instance unavailable for other uses. It is said ‘in first instance’ because evaporated water may come back as rainfall above land somewhere else and polluted water may become clean in the longer term, but these are considered here as secondary effects that will never take away the primary effects.

Impact of Virtual Water

Once you add up all the virtual water you eat and in the products that you buy along with the daily use of water out of the tap, you will have a better idea of what your water footprint is. Water footprints are used to give nations a better consumption-based indicator of water use.


Virtual water trade refers to the idea that when goods and services are exchanged, so is virtual water. When a country imports one tonne of wheat instead of producing it domestically, it is saving about 1,300 cubic meters of real indigenous water. If this country is water-scarce, the water that is 'saved' can be used towards other ends. If the exporting country is water-scarce, however, it has exported 1,300 cubic meters of virtual water since the real water used to grow the wheat will no longer be available for other purposes.

Daniel Zimmer, Director of the World Water Council, in his presentation at the session on "virtual water trade and geopolitics" at the 2003 World Water Forum in Kyoto: The World Water Council is an international collaboration of NGOs, governments and international organisations, It is headquartered in Marseilles, France and it was founded in 1996. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... The World Water Council is an international collaboration of NGOs, governments and international organisations. ... Kyoto )   is a city in the central part of the island of HonshÅ«, Japan. ...

"The contrast in water use can be noticed between continents. In Asia, people consume an average of 1,400 litres of virtual water a day, while in Europe and North America, people consume about 4,000 litres. About 70 per cent of all water used by humans goes into food production. [...]
"Among the biggest net exporter countries of virtual water are the U.S., Canada, Thailand, Argentina, India, Vietnam, France and Brazil. Some of the largest net import countries are Sri Lanka, Japan, the Netherlands, South Korea, China, Spain, Egypt, Germany and Italy."

Water-scarce countries like Israel discourage the export of oranges (relatively heavy water guzzlers) precisely to prevent large quantities of water being exported to different parts of the world. For other uses, see Asia (disambiguation). ... For other uses, see Europe (disambiguation). ... North America North America is a continent[1] in the Earths northern hemisphere and (chiefly) western hemisphere. ... Motto: (Out Of Many, One) (traditional) In God We Trust (1956 to date) Anthem: The Star-Spangled Banner Capital Washington D.C. Largest city New York City None at federal level (English de facto) Government Federal constitutional republic  - President George Walker Bush (R)  - Vice President Dick Cheney (R) Independence from...

In recent years, the concept of virtual water trade has gained weight both in the scientific as well as in the political debate. The notion of the concept is ambiguous. It changes between an analytical, descriptive concept and a political induced strategy. As an analytical concept, virtual water trade represents an instrument which allows the identification and assessment of policy options not only in the scientific but also in the political discourse. As a politically induced strategy the question is, whether virtual water trade can be implemented in a sustainable way, whether the implementation can be managed in a socially, economically and ecologically fashion, and for what countries the concept offers a meaningful option.

In sum, virtual water trade allows a new, amplified perspective on water problems: In the framework of recent developments from a supply-oriented to a demand-oriented management of water resources it opens up new fields of governance and facilitates a differentiation and balancing of different perspectives, basic conditions and interests. Analytically the concept enables to distinguish between global, regional and local levels and their linkages. This means, that water resource problems have to be solved in problemsheds (Tony Allen) if they cannot be successfully addressed in the local or regional watershed. Virtual water trade can thus overcome the hydro-centricity of a narrow watershed view. According to the proceedings of a 2006 conference in Frankfurt, Germany, it seems reasonable to link the new concept with the approach of Integrated water resources management. For other uses, see Frankfurt (disambiguation). ...

Making a Difference

People need to be educated about the situation that exists with virtual water. Since the world is becoming more water stressed, all possible remedies need to be investigated. Raising awareness of virtual water and green water is essential. If people are not informed nothing will be changed. Also, if the revelation of the amount of water actually consumed by each person was made known people might attempt to become more water wise.

Embodied energy

Some researchers have attempted to use the methods of energy analysis, which aim to produce embodied energy estimates, to derive virtual, or embodied water estimates (Lenzen and Foran 2001) Life cycle energy analysis (LCEA) is an approach in which all energy inputs to a product are accounted for, not only direct energy inputs during manufacture, but also all energy inputs needed to produce components, materials and services needed for the manufacturing process. ... There appear to be a number of different understandings of the term embodied energy. ...


  • Allan, T. (1998) Watersheds and problemsheds [4]
  • Australian Food and Grocery Council. 2003. Environment Report 2003. Available online at [5]
  • 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 [6]
  • Chapagain, A.K., A.Y. Hoekstra, H.H.G. Savenije, and R. Gautam (2005) The Water Footprint of Cotton Consumption, Value of Water Research Report Series No.18, UNESCO-IHE, Delft, the Netherlands [7]
  • Falkenmark, M. (2003) Freshwater as shared between society and ecosystems: from divided approaches to integrated challenges, Philosophical Transaction of the Royal Society of London B 358(1440): 2037-2049.
  • Hoekstra, A.Y. (2003) (ed) ‘Virtual water trade: Proceedings of the International Expert Meeting on Virtual Water Trade’ Value of Water Research Report Series No.12, UNESCO-IHE, Delft, the Netherlands [8]
  • Hoekstra, A.Y. and Chapagain, A.K. (2007) Water footprints of nations: water use by people as a function of their consumption pattern, Water Resources Management 21(1): 35-48 [9]
  • Hummel, D., T. Kluge, S. Liehr, M. Hachelaf (2006) Virtual Water Trade. Documentation of an International Expert Workshop. July 3-4, 2006. Frankfurt am Main. ISOE-Materialien Soziale Ökologie No. 24 [10]
  • Lenzen, M., Foran, B. (2001) An Input-Output analysis of Australian water usage, Water Policy, 3, 321-340.
  • UN International year of fresh water - virtual water [11]
  • Vardona,M, Lenzen,M. Peevora, S., Creasera, M. 2007. Water accounting in Australia, Ecological Economics, 61, 650 – 659.

See also


External links

  • Water Footprint A website on water footprints and virtual water maintained by UNESCO-IHE in collaboration with Twente University. Contains a product gallery showing water needs by product, a calculator to assess your own water footprint. Also various publications available for download.
  • Australian Bureau of Statistics Article on Embodied Water
  • Zygmunt, J. (2007) Hidden Waters, A Waterwise briefing on embedded water and water footprints. Online at http://www.waterwise.org.uk.
  • Typographic poster series on Virtual Water and Water footprints of nations, based on the research data of UNCESCO-IHE. http://www.traumkrieger.de/virtualwater/

  Results from FactBites:
Virtual water - Wikipedia, the free encyclopedia (393 words)
The water is said to be virtual because once the wheat is grown, the real water used to grow it is no longer actually contained in the wheat.
In semi-arid and arid areas, knowing the virtual water value of a good or service can be useful towards determining how best to use the scarce water available.
Virtual water trade refers to the idea that when goods and services are exchanged, so is virtual water.
  More results at FactBites »



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