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{{short description|Extent of water use in relation to consumption by people}}
{{Redirect-distinguish|Water consumption|Daily consumption of drinking water}}
[[File:World Water Footprint.png|thumb|upright=1.4|Infographic of water footprints around the world]]
A '''water footprint''' shows the extent of water use in relation to [[Consumption (economics)|consumption]] by people.<ref name="nations">{{cite web|title=Water footprints of nations: Water use by people as a function of their consumption pattern|url=http://waterfootprint.org/media/downloads/Hoekstra_and_Chapagain_2007.pdf|publisher=Water Footprint Network|access-date=3 March 2018|archive-date=17 April 2018|archive-url=https://web.archive.org/web/20180417110409/http://waterfootprint.org/media/downloads/Hoekstra_and_Chapagain_2007.pdf|url-status=dead}}</ref> The water footprint of an individual, community, or business is defined as the total volume of [[fresh water]] used to produce the goods and services consumed by the individual or community or produced by the business. Water use is measured in water volume consumed ([[evaporated]]) and/or polluted per unit of time. A water footprint can be calculated for any well-defined group of [[consumer]]s (e.g., an individual, family, village, city, province, state, or nation) or [[Production (economics)|producers]] (e.g., a public organization, private enterprise, or economic sector), for a single [[process]] (such as growing rice) or for any [[Product (business)|product]] or [[Service (economics)|service]].<ref name=waterfootprintorg>{{cite web|title=Waterfootprint.org: Water footprint and virtual water|url=https://www.waterfootprint.org/water-footprint-2/g/?page=files/home|publisher=The Water Footprint Network|access-date=30 October 2023}}</ref>

Traditionally, water use has been approached from the production side, by quantifying the following three columns of water use: water withdrawals in the [[Agriculture|agricultural]], [[Manufacturing|industrial]], and [[Home|domestic]] sector. While this does provide valuable data, it is a limited way of looking at water use in a [[Globalization|globalised]] world, in which products are not always consumed in their country of origin. International trade of agricultural and industrial products in effect creates a global flow of [[virtual water]], or ''embodied water'' (akin to the concept of [[embodied energy]]).<ref name="nations" />

In 2002, the water footprint concept was introduced in order to have a consumption-based [[Economic indicator|indicator]] of water use, that could provide useful information in addition to the traditional production-sector-based indicators of water use. It is analogous to the [[ecological footprint]] concept introduced in the 1990s. The water footprint is a geographically explicit indicator, not only showing volumes of water use and pollution, but also the locations.<ref>[https://waterfootprint.org/en/water-footprint/glossary/ Definition] taken from the Hoekstra, A.Y. and Chapagain, A.K. (2008) Globalization of water: Sharing the planet's freshwater resources, Blackwell Publishing, Oxford, UK.</ref> The global issue of water footprinting underscores the importance of fair and sustainable resource management. Due to increasing water shortages, climate change, and environmental concerns, transitioning towards a fair impact of water use is critical. The water footprint concept offers detailed insights for adequate and equitable water resource management. It advocates for a balanced and sustainable water-use approach, aiming to tackle global challenges. This approach is essential for responsible and equitable water resource utilization globally. Thus, it gives a grasp on how economic choices and processes influence the availability of adequate water resources and other ecological realities across the globe (and vice versa).

==Definition and measures==
There are many different aspects to water footprint and therefore different definitions and measures to describe them. Blue water footprint refers to groundwater or surface water usage, green water footprint refers to rainwater, and grey water footprint refers to the amount of water needed to dilute pollutants.<ref>{{Cite journal|title=16030, 1841-01-13, PERROT (fabrique)|url=http://dx.doi.org/10.1163/2210-7886_asc-16030|access-date=2021-10-25|website=Art Sales Catalogues Online|doi=10.1163/2210-7886_asc-16030 }}</ref>

===Blue water footprint===
A ''blue water footprint'' refers to the volume of water that has been sourced from [[Surface water|surface]] or [[groundwater]] resources (lakes, rivers, wetlands and [[aquifer]]s) and has either evaporated (for example while [[irrigation|irrigating]] crops), or been incorporated into a product or taken from one body of water and returned to another, or returned at a different time. Irrigated agriculture, industry and domestic water use can each have a blue water footprint.<ref name="whatis">{{cite web|title=What is a water footprint?|url=http://waterfootprint.org/en/water-footprint/what-is-water-footprint/|publisher=The Water Footprint Network|access-date=8 March 2018}}</ref>

===Green water footprint===
A ''green water footprint'' refers to  the amount of water from [[precipitation]] that, after having been stored in the root zone of the soil (green water), is either lost by [[evapotranspiration]] or incorporated by plants. It is particularly relevant for agricultural, [[Horticulture|horticultural]] and [[forestry]] products.<ref name="whatis" />

===Grey water footprint===
A ''grey water footprint'' refers to the volume of water that is required to dilute [[Water pollution|pollutants]] (industrial discharges, seepage from tailing ponds at mining operations, untreated municipal wastewater, or [[nonpoint source pollution]] such as agricultural runoff or [[urban runoff]]) to such an extent that the quality of the water meets agreed water quality standards.<ref name="whatis" /> It is calculated as:

:<math>\frac{L}{c_\text{max} - c_\text{nat}}</math>

where ''L'' is the [[Measures of pollutant concentration|pollutant load]] (as [[mass flux]]), ''c''<sub>max</sub> the maximum allowable concentration and ''c''<sub>nat</sub> the natural concentration of the pollutant in the receiving water body (both expressed in mass/volume).<ref name="TheWaterFootprintAssessmentManual">{{cite web|title=The Water Footprint Assessment Manual|url=http://www.waterfootprint.org/?page=files/WaterFootprintAssessmentManual|publisher=Water Footprint Network|access-date=2015-01-20|archive-date=2015-02-10|archive-url=https://web.archive.org/web/20150210094744/http://www.waterfootprint.org/?page=files%2FWaterFootprintAssessmentManual|url-status=dead}}</ref>

===Calculation for different factors===
The water footprint of a process is expressed as [[volumetric flow rate]] of water. That of a product is the whole footprint (sum) of processes in its complete supply chain divided by the number of product units. For consumers, businesses and geographic area, water footprint is indicated as volume of water per time, in particular:<ref name="TheWaterFootprintAssessmentManual" />

* That of a consumer is the sum of footprint of all consumed products.
* That of a community or a nation is the sum for all of its members resp. inhabitants.
* That of a business is the footprint of all produced goods.
* That of a geographically delineated area is the footprint of all processes undertaken in this area. The virtual change in water of an area is the net import of virtual water ''V<sub>i, net</sub>'', defined as the difference of the gross import ''V<sub>i</sub>'' of virtual water from its gross export ''V<sub>e</sub>''. The water footprint of national consumption ''WF<sub>area,nat</sub>'' results from this as the sum of the water footprint of national area and its virtual change in water.

==History==
The concept of a ''water footprint'' was coined in 2002, by [[Arjen Hoekstra]], Professor in [[water management]] at the [[University of Twente]], [[Netherlands]], and co-founder and scientific director of the Water Footprint Network, whilst working at the [[UNESCO-IHE]] Institute for Water Education, as a [[System of measurement|metric]] to measure the amount of water consumed and polluted to produce goods and services along their full supply chain.<ref name="aims">{{cite web|url=http://waterfootprint.org/en/about-us/aims-history/ |title=Water Footprint Network - Aims & history |publisher=Water Footprint Network |access-date= 27 January 2018}}</ref><ref>Jayne M. Godfrey, Keryn Chalmers. 2012 Water Accounting: International Approaches to Policy and Decision-making. Edward Elgar Publishing. page222</ref><ref>Hoekstra, A.Y. (2003) (ed) Virtual water trade: Proceedings of the International Expert Meeting on Virtual Water Trade, IHE Delft, the Netherlands [http://www.waterfootprint.org/Reports/Report12.pdf]</ref>  Water footprint is one of a family of [[ecological footprint]] indicators, which also includes [[carbon footprint]] and [[land footprint]]. The water footprint concept is further related to the idea of [[virtual water]] trade introduced in the early 1990s by Professor [[John Anthony Allan|John Allan]] (2008 [[Stockholm Water Prize|Stockholm Water Prize Laureate]]). The most elaborate publications on how to estimate water footprints are a 2004 report on the ''Water footprint of nations'' from UNESCO-IHE,<ref>{{cite web| url=http://www.waterfootprint.org/Reports/Report16Vol1.pdf | access-date=2023-11-07| title=Water footprints of nations | volume=1 | publisher=UNESCO-IHE}}</ref> the 2008 book ''Globalization of Water'',<ref>''Globalization of Water'', A.Y. Hoekstra and A.K. Chapagain, Blackwell, 2008</ref> and the 2011 manual ''The water footprint assessment manual: Setting the global standard''.<ref name="Hoekstra-2011">{{cite book|last=Hoekstra|first=Arjen|url=https://www.waterfootprint.org/media/downloads/TheWaterFootprintAssessmentManual_2.pdf|title=The water footprint assessment manual: Setting the global standard|publisher=Earthscan|year=2011|isbn=978-1-84971-279-8|location=London}}</ref>  Cooperation between global leading institutions in the field has led to the establishment of the Water Footprint Network in 2008.

===Water Footprint Network (WFN)===
<!-- linked from redirect [[Water Footprint Network]] -->
The Water Footprint Network is an international learning community (a [[Nonprofit organization|non-profit foundation]] under [[Dutch Law|Dutch law]]) which serves as a platform for sharing knowledge, tools and innovations among governments, businesses and communities concerned about growing [[water scarcity]] and increasing [[water pollution]] levels, and their impacts on people and nature. The network consists of around 100 partners from all sectors – producers, investors, suppliers and regulators – as well as [[non-governmental organisation]]s and [[Academic staff|academics]]. It describes its mission as follows: <blockquote> To provide [[Evidence-based practice|science-based]], practical solutions and strategic insights that empower companies, governments, individuals and small-scale producers to transform the way we use and share fresh water within earth's limits.<ref name="aims" /></blockquote>

===International standard===
In February 2011, the Water Footprint Network, in a global collaborative effort of environmental organizations, companies, research institutions and the UN, launched the ''Global Water Footprint Standard''. In July 2014, the [[International Organization for Standardization]] issued ''ISO 14046:2014, Environmental management—Water footprint—Principles, requirements and guidelines'', to provide practical guidance to practitioners from various backgrounds, such as large companies, public authorities, non-governmental organizations, academic and research groups as well as small and medium enterprises, for carrying out a water footprint assessment. The ISO standard is based on [[life-cycle assessment]] (LCA) principles and can be applied for different sorts of assessment of products and companies.<ref name="ISO14046">{{cite web|url=http://www.iso.org/iso/catalogue_detail?csnumber=43263 |title='''ISO 14046:2014''' Environmental management -- Water footprint -- Principles, requirements and guidelines |publisher=International Organization for Standardization |access-date= 4 March 2018}}</ref>

===Life-cycle assessment of water use===
[[Life-cycle assessment]] (LCA) is a systematic, phased approach to assessing the environmental aspects and potential impacts that are associated with a product, process or service.  "Life cycle" refers to the major activities connected with the product's life-span, from its manufacture, use, and maintenance, to its final disposal, and also including the acquisition of [[raw material]] required to manufacture the product.<ref>{{cite book|last=Scientific Applications International Corporations (SAIC)|title=Life Cycle Assessment: Principles and Practice|year=2006|publisher=SAIC|location=Reston, VA}}</ref>  Thus a method for assessing the environmental impacts of freshwater consumption was developed.  It specifically looks at the damage to three areas of protection: human health, ecosystem quality, and resources.  The consideration of water consumption is crucial where water-intensive products (for example agricultural goods) are concerned that need to therefore undergo a life-cycle assessment.<ref>{{cite journal|last=Pfister|first=Stephan|author2=Koehler, Annette |author3=Hellweg, Stefanie |title=Assessing the Environmental Impacts of Freshwater Consumption in LCA|journal=Environmental Science|date=20 March 2009|volume=43|issue=11|pages=4008–104|bibcode=2009EnST...43.4098P|doi=10.1021/es802423e|pmid=19569336|doi-access=free}}</ref>  In addition, regional assessments are equally as necessary as the impact of water use depends on its location.  In short, LCA is important as it identifies the impact of water use in certain products, consumers, companies, nations, etc. which can help reduce the amount of water used.<ref>{{cite journal |last1=Pfister |first1=Stephan |last2=Boulay |first2=Anne-Marie |last3=Berger |first3=Markus |last4=Hadjikakou |first4=Michalis |last5=Motoshita |first5=Masaharu |last6=Hess |first6=Tim |last7=Ridoutt |first7=Brad |last8=Weinzettel |first8=Jan |last9=Scherer |first9=Laura |last10=Döll |first10=Petra |last11=Manzardo |first11=Alessandro |last12=Núñez |first12=Montserrat |last13=Verones |first13=Francesca |last14=Humbert |first14=Sebastien |last15=Buxmann |first15=Kurt |last16=Harding |first16=Kevin |last17=Benini |first17=Lorenzo |last18=Oki |first18=Taikan |last19=Finkbeiner |first19=Matthias |last20=Henderson |first20=Andrew |title=Understanding the LCA and ISO water footprint: A response to Hoekstra (2016) "A critique on the water-scarcity weighted water footprint in LCA" |journal=Ecological Indicators |date=January 2017 |volume=72 |pages=352–359 |doi=10.1016/J.ECOLIND.2016.07.051|pmid=30344449 |pmc=6192425 |bibcode=2017EcInd..72..352P }}</ref>

=== Water positive ===
The [[Water Positive]] initiative can be defined as the concept where an entity, such as a company, community, or individual, goes beyond simply conserving water and actively contributes to the sustainable management and restoration of water resources. A commercial or residential development is considered water positive when it generates more water than it consumes. This involves implementing practices and technologies that reduce water consumption, improve water quality, and enhance water availability. The goal of being water positive is to leave a positive impact on water [[ecosystem]] and ensure that more water is conserved and restored than is used or depleted.<ref>{{Cite web |last=Loher |first=Nicole |date=2023-03-15 |title=What Does it Mean to Be 'Water Positive'? |url=https://sustainability.fb.com/blog/2023/03/15/what-does-it-mean-to-be-water-positive/ |access-date=2023-12-22 |website=Meta Sustainability |language=en-US}}</ref><ref>{{Cite web |date=2022-05-10 |title=¿Qué es ser "water positive"? El nuevo objetivo de las grandes compañías |url=https://www.hidrologiasostenible.com/que-es-ser-water-positive-el-nuevo-objetivo-de-las-grandes-companias/ |access-date=2023-12-22 |website=Hidrología Sostenible |language=es}}</ref><ref>{{Cite news |last=Schupak |first=Amanda |date=2021-10-14 |title=Corporations are pledging to be 'water positive'. What does that mean? |language=en-GB |work=The Guardian |url=https://www.theguardian.com/environment/2021/oct/14/water-positive-pledge-corporations |access-date=2023-12-22 |issn=0261-3077}}</ref><ref>{{Cite web |last=Pandey |first=Rajdeep |date=2018-10-23 |title=Water Positive Campus |url=https://blog.enviraj.com/2018/10/water-positive-campus.html |access-date=2024-04-24 |website=Enviraj}}</ref>

==Water availability==
[[File:Total Renewable Water Resources Per Capita (2020).svg|thumb|Total renewable water resources per capita in 2020]]

Globally, about 4 percent of [[precipitation]] falling on land each year (about {{convert|117,000|km3|abbr=on}}),<ref>{{cite journal | last1 = Schneider | first1 = U. | display-authors = etal | year = 2014 | title = GPCC's new land surface precipitation climatology based on quality-controlled in-situ data and its role in quantifying the global water cycle | journal = Theoretical and Applied Climatology | volume = 115 | issue = 1–2 | pages = 15–40 | doi = 10.1007/s00704-013-0860-x | bibcode = 2014ThApC.115...15S | doi-access = free }}</ref> is used by rain-fed agriculture and about half is subject to evaporation and transpiration in [[forest]]s and other natural or quasi-natural landscapes.<ref>{{cite web| access-date=2023-11-07| publisher=FAO|title=Water Use| url=http://www.fao.org/nr/water/aquastat/water_use/index.stm#tables}}</ref>  The remainder, which goes to [[groundwater]] replenishment and [[surface runoff]], is sometimes called "total actual renewable freshwater resources".  Its magnitude was in 2012 estimated at {{convert|52,579|km3|abbr=on}}/year.<ref name="Frenken2012">Frenken, K. and V. Gillet.  2012.  [[Irrigation]] water requirement and water withdrawal by country.  AQUASTAT, FAO.</ref>  It represents water that can be used either in-stream or after withdrawal from surface and groundwater sources.  Of this remainder, about {{convert|3,918|km3|abbr=on}} were withdrawn in 2007, of which {{convert|2,722|km3|abbr=on}}, or 69 percent, were used by agriculture, and {{convert|734|km3|abbr=on}}, or 19 percent, by other industry.<ref>{{cite web|publisher=FAO| year=2014| title=Water withdrawal by sector, around 2007 | url=http://www.fao.org/nr/water/aquastat/tables/WorldData-Withdrawal_eng.pdf | access-date=2023-11-07}}</ref>  Most agricultural use of withdrawn water is for [[irrigation]], which uses about 5.1 percent of total actual renewable [[freshwater]] resources.<ref name="Frenken2012" />  World water use has been growing rapidly in the last hundred years.<ref>[https://www.newscientist.com/channel/earth/mg19926700.100-looming-water-crisis-simply-a-management-problem.html "Looming water crisis simply a management problem"] by Jonathan Chenoweth, [[New Scientist]] 28 Aug., 2008, pp. 28-32.</ref><ref>{{Cite journal|last1=Ritchie|first1=Hannah|author1-link=Hannah Ritchie |last2=Roser|first2=Max|author2-link=Max Roser |date=2017-11-20|title=Water Use and Stress|url=https://ourworldindata.org/water-use-stress|journal=Our World in Data}}</ref>

== Water footprint of products (agricultural sector) ==
The water footprint of a product 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.<ref>{{Cite web |url=http://www.waterfootprint.org/?page=files/Glossary |title=WFN Glossary |access-date=2012-10-02 |archive-date=2015-04-01 |archive-url=https://web.archive.org/web/20150401202137/http://www.waterfootprint.org/?page=files/Glossary |url-status=dead }}</ref> The Water Footprint Network maintains a global database on the water footprint of products: WaterStat.<ref>{{Cite web |url=http://www.waterfootprint.org/?page=files/WaterStat |title=WaterStat |access-date=2012-10-02 |archive-date=2015-04-01 |archive-url=https://web.archive.org/web/20150401202134/http://www.waterfootprint.org/?page=files/WaterStat |url-status=dead }}</ref> Nearly over 70% of the water supply worldwide is used in the agricultural sector.<ref name="ReferenceA">{{Cite journal|last1=Chinnasamy|first1=Pennan|last2=Agoramoorthy|first2=Govindasamy|date=2015-05-01|title=Groundwater Storage and Depletion Trends in Tamil Nadu State, India|journal=Water Resources Management|language=en|volume=29|issue=7|pages=2139–2152|doi=10.1007/s11269-015-0932-z|bibcode=2015WatRM..29.2139C |s2cid=54761901|issn=1573-1650}}</ref>{{Clarify|reason=The phrase "nearly over 70%" is confusing, as those first two words are contradictory. Since access to the source is restricted by a paywall, it is not clear whether this term has been taken directly from the source, or whether it is an error that was made after the fact.|date=April 2021}}

The water footprints involved in various diets vary greatly, and much of the variation tends to be associated with levels of meat consumption.<ref>Vanham, D., M. M.Mekonnen and A. Y. Hoekstra.  2013.  The water footprint of the EU for different diets.  Ecological Indicators 32: 1-8.</ref> The following table gives examples of estimated global average water footprints of popular agricultural products.<ref name="Mekonnen2010a">Mekonnen, M. M. and A. Y. Hoekstra. 2010. The green, blue and grey water footprint of farm animals and animal products. Volume 1: Main report. UNESCO-IHE., Institute for Water Education.  50 pp.</ref><ref>Mekonnen, M. M. and A. Y. Hoekstra. 2010. The green, blue and grey water footprint of crops and derived crop products. Volume 2. Appendices main report. Value of Water Research Report Series No. 47.  UNESCO-IHE Institute for Water Education. 1196 pp.</ref><ref name="Danwatch2019">{{cite web |title=How much water does it take to grow an avocado? |url=https://old.danwatch.dk/en/undersogelseskapitel/how-much-water-does-it-take-to-grow-an-avocado/ |website=Danwatch.dk |access-date=7 October 2019 |archive-url=https://web.archive.org/web/20191007172453/https://old.danwatch.dk/en/undersogelseskapitel/how-much-water-does-it-take-to-grow-an-avocado/ |archive-date=7 October 2019 |date=2019}}</ref>

{| class="wikitable sortable"
|-
! Product || Global average water footprint, L/kg
|-
| almonds, shelled || 16,194
|-
|apple
|822
|-
|avocado
|283
|-
|banana
|790
|-
| beef || 15,415
|-
|bread, wheat
|1,608
|-
|butter
|5,553
|-
|cabbage
|237
|-
|cheese
|3,178
|-
|chicken
|4,325
|-
| chocolate || 17,196
|-
| cotton lint || 9,114
|-
|cucumber
|353
|-
|dates
|2,277
|-
|eggs
|3,300
|-
|groundnuts, shell
|2,782
|-
|leather (bovine)
|17,093
|-
| lettuce || 238
|-
|maize
|1,222
|-
|mango/guava
|1,800
|-
| milk || 1,021
|-
| olive oil || 14,430
|-
|orange
|560
|-
|pasta (dry)
|1,849
|-
|peach/nectarine
|910
|-
|pork
|5,988
|-
|potato
|287
|-
|pumpkin
|353
|-
|rice
|2,497
|-
| tomatoes, fresh || 214
|-
| tomatoes, dried || 4,275
|-
| vanilla beans || 126,505
|-
|}

(For more product water footprints: see the [http://www.waterfootprint.org/?page=files/productgallery Product Gallery of the Water Footprint Network] {{Webarchive|url=https://web.archive.org/web/20200730100009/https://www.waterfootprint.org/en/ |date=2020-07-30 }})

==Water footprint of companies (industrial sector) ==
The water footprint of a business, the 'corporate water footprint', is defined as the total volume of freshwater that is used directly or indirectly to run and support a business. It is the total volume of water use to be associated with the use of the business outputs. The water footprint of a business consists of water used for producing/manufacturing or for supporting activities and the indirect water use in the producer's supply chain.

[[The Carbon Trust]] argue that a more robust approach is for businesses to go beyond simple volumetric measurement to assess the full range of water impact from all sites.  Its work with leading global pharmaceutical company [[GlaxoSmithKline]] (GSK) analysed four key categories: water availability, water quality, health impacts, and licence to operate (including reputational and regulatory risks) in order to enable GSK to quantitatively measure, and credibly reduce, its year-on-year water impact.<ref>[http://www.carbontrust.com/news/2014/11/water-water-everywhere-business-water-consumption "Water, water everywhere... or is it?"], ''[[The Carbon Trust]]'', 26 November 2014. Retrieved on 20 January 2015.</ref>

The [[Coca-Cola Company]] operates over a thousand manufacturing plants in about 200 countries. Making its drink uses a lot of water. Critics say its water footprint has been large. Coca-Cola has started to look at its [[water sustainability]].<ref>{{cite web|title=2013 Water Report: The Coca-Cola Company|url=http://www.coca-colacompany.com/2013-water-stewardship-replenish-report/|publisher=The Coca-Cola Company|access-date=8 April 2014|archive-date=19 April 2014|archive-url=https://web.archive.org/web/20140419163040/http://www.coca-colacompany.com/2013-water-stewardship-replenish-report/|url-status=dead}}</ref>  It has now set out goals to reduce its water footprint such as treating the water it uses so it goes back into the environment in a clean state. Another goal is to find sustainable sources for the raw materials it uses in its drinks, such as [[sugarcane]], [[Orange (fruit)|oranges]], and [[maize]]. By making its water footprint better, the company can reduce costs, improve the environment, and benefit the communities in which it operates.<ref name="naumann" />

== Water footprint of individual consumers (domestic sector) ==
The water footprint of an individual refers to the sum of their direct and indirect freshwater use. The direct water use is the water used at home, while the indirect water use relates to the total volume of freshwater that is used to produce the goods and services consumed.

The average global water footprint of an individual is 1,385 m<sup>3</sup> per year. Residents of some example nations have water footprints as shown in the table:
{| class="wikitable"
|-
! Nation !! annual water footprint
|-
| [[China]] || 1,071 m<sup>3</sup><ref name="WF-CN-IN-Hoekstra">{{cite journal|last1=Hoekstra|first1=AY|year=2012|title=The Water Footprint of Humanity|url=http://doc.utwente.nl/80894/1/Hoekstra-Mekonnen-2012-water-footprint-of-humanity.pdf|journal=[[PNAS]]|volume=109|issue=9|pages=3232–3237|bibcode=2012PNAS..109.3232H|doi=10.1073/pnas.1109936109|pmc=3295316|pmid=22331890|doi-access=free}}</ref>
|-
| [[Finland]] || 1,733 m<sup>3</sup><ref>Data obtained from the Finnish Wikipedia article page [[:fi:Vesijalanjälki|Vesijalanjälki]]</ref>{{Unreliable source?|date=June 2024}}
|-
| [[India]] || 1,089 m<sup>3</sup><ref name="WF-CN-IN-Hoekstra" />
|-
| [[United Kingdom]] || 1,695 m<sup>3</sup><ref>{{cite journal|author1=Chapagain, A.K.|author2=Orr, S.|name-list-style=amp|title=U.K. Water Footprint: The Impact of the U.K.'s Food and Fibre Consumption on Global Water Resources, Volume 1|url=http://assets.wwf.org.uk/downloads/water_footprint_uk.pdf|journal=WWF-UK}} and volume 2 {{cite journal|author1=Chapagain, A.K.|author2=Orr, S.|name-list-style=amp|title=Volume 2|url=http://assets.wwf.org.uk/downloads/uk_waterfootprint_v2.pdf|journal=WWF-UK}}</ref>
|-
| [[United States]] || 2,842 m<sup>3</sup><ref>{{cite news|url=http://journalistsresource.org/studies/environment/sustainability/water-footprint-humanity/|title=The Water Footprint of Humanity}} JournalistsResource.org, retrieved 20 March 2012</ref>
|}

== Water footprint of nations ==
[[File:Water Footprint per capita.jpg|thumb|400px|Global view of national per capita water footprints]]
The water footprint of a nation is the amount of water used to produce the goods and services consumed by the inhabitants of that nation. Analysis of the water footprint of nations illustrates the global dimension of water consumption and pollution, by showing that several countries rely heavily on foreign water resources and that (consumption patterns in) many countries significantly and in various ways impact how, and how much, water is being consumed and polluted elsewhere on Earth. International water dependencies are substantial and are likely to increase with continued global [[Free trade|trade liberalisation]]. The largest share (76%) of the virtual water flows between countries is related to international trade in crops and derived crop products. Trade in animal products and industrial products contributed 12% each to the global virtual water flows. The four major direct factors determining the water footprint of a country are: volume of consumption (related to the [[gross national income]]); consumption pattern (e.g. high versus low [[List of countries by meat consumption|meat consumption]]); climate (growth conditions); and agricultural practice (water use efficiency).<ref name="nations" />

===Production or consumption===
The assessment of total water use in connection to consumption can be approached from both ends of the [[supply chain]].<ref>{{cite web|url=http://waterfootprint.org/en/water-footprint/national-water-footprint/|title=National water footprint|website=waterfootprint.org|access-date=10 March 2018}}</ref> The water footprint of '''production''' estimates how much water from local sources is used or polluted in order to provide the goods and services produced in that country. The water footprint of '''consumption''' of a country looks at the amount of water used or polluted (locally, or in the case of imported goods, in other countries) in connection with all the goods and services that are consumed by the inhabitants of that country. The water footprint of production and that of consumption, can also be estimated for any administrative unit such as a city, province, river basin or the entire world.<ref name="nations" />

===Absolute or per capita===
The absolute water footprint is the total sum of water footprints of all people. A country's [[per capita]] water footprint (that nation's water footprint divided by its number of inhabitants) can be used to compare its water footprint with those of other nations.

The global water footprint in the period 1996–2005 was 9.087 Gm<sup>3</sup>/yr (Billion Cubic Metres per year, or 9.087.000.000.000.000 liters/year), of which 74% was and green, 11% blue, 15% grey. This is an average amount per capita of 1.385 Gm<sup>3</sup>/yr., or 3.800 liters per person per day.<ref name=Morelli>{{cite web|title=Angela Morelli - The Global Water Footprint of Humanity|publisher=TEDxOslo |url=https://www.youtube.com/watch?v=p8YHa1W_neI | website=youtube.com|date=21 June 2011 }}</ref> On average 92% of this is embedded in agricultural products consumed, 4.4% in industrial products consumed, and 3.6% is domestic water use. The global water footprint related to producing goods for export is 1.762 Gm<sup>3</sup>/y.<ref name="humanity">{{cite journal |last1=Hoekstra |first1=Arjen Y. |last2=Mekonnen |first2=Mesfin M. |date=28 February 2012 |title=The water footprint of humanity |journal=[[Proceedings of the National Academy of Sciences of the United States of America|PNAS]] |volume=109 |issue=9 |pages=3232–3237 |doi=10.1073/pnas.1109936109 |pmid=22331890 |pmc=3295316 |bibcode=2012PNAS..109.3232H |doi-access=free }}</ref>

In absolute terms, India is the country with the largest water footprint in the world, a total of 987 Gm<sup>3</sup>/yr. In relative terms (i.e. taking population size into account), the people of the USA have the largest water footprint, with 2480 m<sup>3</sup>/yr per capita, followed by the people in south European countries such as Greece, Italy and Spain (2300–2400 m<sup>3</sup>/yr per capita). High water footprints can also be found in Malaysia and Thailand. In contrast, the Chinese people have a relatively low per capita water footprint with an average of 700 m<sup>3</sup>/yr.<ref name="nations" /> (These numbers are also from the period 1996-2005.)

===Internal or external===
[[File:GlobalWaterFootprint by sector.1500.jpg|thumb|560px|Global average numbers and composition of all national water footprints, internal and external]]
The '''internal water footprint''' is the amount of water used from domestic water resources; the '''external water footprint''' is the amount of water used in other countries to produce goods and services imported and consumed by the inhabitants of the country. When assessing the water footprint of a nation, it is crucial to take into account the international flows of [[virtual water]] (also called ''embodied water'', i.e. the water used or polluted in connection to all agricultural and industrial commodities) leaving and entering the country. When taking the use of domestic water resources as a starting point for calculating a nation's water footprint, one should subtract the virtual water flows that leave the country and add the virtual water flows that enter the country.<ref name="nations" />

The external part of a nation's water footprint varies strongly from country to country. Some African nations, such as Sudan, Mali, Nigeria, Ethiopia, Malawi and Chad have hardly any external water footprint, simply because they have little import. Some European countries on the other hand—e.g. Italy, Germany, the UK and the Netherlands—have external water footprints that constitute 50–80% of their total water footprint. The agricultural products that on average contribute most to the external water footprints of nations are: bovine meat, soybean, wheat, cocoa, rice, cotton and maize.<ref name="nations" />

The top 10 gross virtual water exporting nations, which together account for more than half of the global virtual water export, are the United States (314 Gm<sup>3</sup>/year), China (143 Gm<sup>3</sup>/year), India (125 Gm<sup>3</sup>/year), Brazil (112 Gm<sup>3</sup>/year), Argentina (98 Gm<sup>3</sup>/year), Canada (91 Gm<sup>3</sup>/year), Australia (89 Gm<sup>3</sup>/year), Indonesia (72 Gm<sup>3</sup>/year), France (65 Gm<sup>3</sup>/year), and Germany (64 Gm<sup>3</sup>/year).<ref name="humanity" />

The top 10 gross virtual water importing nations are the United States (234 Gm<sup>3</sup>/year), Japan (127 Gm<sup>3</sup>/year), Germany (125 Gm<sup>3</sup>/year), China (121 Gm<sup>3</sup>/year), Italy (101 Gm<sup>3</sup>/year), Mexico (92 Gm<sup>3</sup>/year), France (78 Gm<sup>3</sup>/year), the United Kingdom (77 Gm<sup>3</sup>/year), and The Netherlands (71 Gm<sup>3</sup>/year).<ref name="humanity" />

== Water use in continents ==

=== Europe ===
{{See also |:Category:Droughts in Europe}}
Each [[Demographics of the European Union|EU citizen]] consumes 4,815 litres of water per day on average; 44% is used in power production primarily to cool thermal plants or [[Nuclear power in the European Union|nuclear power]] plants. Energy production annual water consumption in the EU 27 in 2011 was, in billion m<sup>3</sup>: for gas 0.53, coal 1.54 and nuclear 2.44. [[Wind energy]] avoided the use of 387 million cubic metres (mn m<sup>3</sup>) of water in 2012, avoiding a cost of €743 million.<ref>[http://www.ewea.org/fileadmin/files/library/publications/reports/Saving_water_with_wind_energy.pdf  Saving water with wind energy], EWEA June 2014</ref><ref>{{cite web|url=http://www.ewea.org/publications/reports/saving-water-with-wind-energy/|title=Saving water with wind energy Summary EWEA|website=EWEA.org|access-date=5 May 2017}}</ref>

=== Asia ===
In south India the state Tamil Nadu is one of the main agricultural producers in India and it relies largely in groundwater for irrigation. In ten years, from 2002 to 2012, the Gravity Recovery and Climate Experiment calculated that the groundwater reduced in 1.4 m yr−1, which "is nearly 8% more than the annual recharge rate."<ref name="ReferenceA"/>

==Environmental water use==
Although agriculture's water use includes provision of important terrestrial environmental values (as discussed in the "[[#Water footprint of products (agricultural sector)|Water footprint of products]]" section above), and much "green water" is used in maintaining forests and wild lands, there is also direct environmental use (e.g. of surface water) that may be allocated by governments. For example, in [[California]], where water use issues are sometimes severe because of drought, about 48 percent of "dedicated water use" in an average water year is for the environment (somewhat more than for agriculture).<ref>{{cite web|url=http://www.water.ca.gov/swp/watersupply.cfm|title=California State Water Project-Water Supply|website=www.Water.ca.gov|access-date=5 May 2017|archive-date=7 April 2017|archive-url=https://web.archive.org/web/20170407071326/http://www.water.ca.gov/swp/watersupply.cfm|url-status=dead}}</ref> Such environmental water use is for keeping streams flowing, maintaining aquatic and riparian habitats, keeping wetlands wet, etc.

==Criticism==

===Insufficient consideration of consequences of proposed water saving policies to farm households===
According to Dennis Wichelns of the [[International Water Management Institute]]: "Although one goal of virtual water analysis is to describe opportunities for improving [[water security]], there is almost no mention of the potential impacts of the prescriptions arising from that analysis on farm households in industrialized or developing countries. It is essential to consider more carefully the inherent flaws in the virtual water and water footprint perspectives, particularly when seeking guidance regarding policy decisions."<ref>{{cite journal |last=Wichelns |first=Dennis |date=2010 |title=Virtual water and water footprints offer limited insight regarding important policy questions |url=http://www.iwmi.cgiar.org/publications/journal-articles/ |journal=International Journal of Water Resources Development |volume=26 |issue=4 |pages=639–651 |doi=10.1080/07900627.2010.519494 |bibcode=2010IJWRD..26..639W |s2cid=154664691 |access-date=21 January 2015}}</ref>

===Regional water scarcity should be taken into account when interpreting water footprint===
The application and interpretation of water footprints may sometimes be used to promote industrial activities that lead to facile criticism of certain products. For example, the 140&nbsp;litres required for coffee production for one cup<ref name="waterfootprintorg" /> might be of no harm to water resources if its cultivation occurs mainly in humid areas, but could be damaging in more arid regions. Other factors such as hydrology, climate, geology, topography, population and demographics should also be taken into account. Nevertheless, high water footprint calculations do suggest that environmental concern may be appropriate.

Many of the criticisms, including the above ones, compare the description of the water footprint of a [[Water system (disambiguation)|water system]] to generated impacts, which is about its performance. Such a comparison between descriptive and performance factors and indicators is basically flawed.<ref name="Haie-2018">{{Cite journal|last1=Haie|first1=N.|last2=Freitas|first2=M.R.|last3=Pereira|first3=J.C.|date=2018|title=Integrating Water Footprint and Sefficiency: Overcoming Water Footprint Criticisms and Improving Decision Making|url=http://www.water-alternatives.org/index.php/alldoc/articles/vol11/v11issue3/471-a11-3-24/file|journal=Water Alternatives|volume=11|pages=933–956}}</ref>

The use of the term ''footprint'' can also confuse people familiar with the notion of a [[carbon footprint]], because the water footprint concept includes sums of water quantities without necessarily evaluating related impacts. This is in contrast to the carbon footprint, where carbon emissions are not simply summarized but normalized by CO<sub>2</sub> emissions, which are globally identical, to account for the environmental harm. The difference is due to the somewhat more complex nature of water; while involved in the global hydrological cycle, it is expressed in conditions both local and regional through various forms like river basins, watersheds, on down to groundwater (as part of larger [[aquifer]] systems). Furthermore, looking at the definition of the footprint itself, and comparing [[ecological footprint]], [[carbon footprint]] and water footprint, we realize that the three terms are indeed legitimate.<ref name="Haie-2018" />

==Sustainable water use==
[[Sustainable]] water use involves the rigorous assessment of all source of clean water to establish the current and future rates of use, the impacts of that use both downstream and in the wider area where the water may be used and the impact of contaminated water streams on the environment and economic well being of the area. It also involves the implementation of [[social policy|social policies]] such as [[water pricing]] in order to manage water demand.<ref>{{cite web|url=http://www.eea.europa.eu/themes/water/water-resources/policies-and-measures-to-promote-sustainable-water-use|publisher=Europeanm Environment Agency|title=Policies and measure to promote sustainable water use|access-date=26 April 2016|date=18 February 2008}}</ref> In some localities, water may also have spiritual relevance and the use of such water may need to take account of such interests. For example, the [[Māori people|Maori]] believe that water is the source and foundation of all life and have many spiritual associations with water and places associated with water.<ref>{{cite web|url=http://www.teara.govt.nz/en/tangaroa-the-sea/page-5|title=Tangaroa – the sea - Water as the source of life|author=e Ahukaramū Charles Royal|publisher=Encyclopaedia of New Zealand|date=22 September 2012}}</ref>  On a national and global scale, water sustainability requires strategic and long term planning to ensure appropriate sources of clean water are identified and the environmental and economic impact of such choices are understood and accepted.<ref>{{cite book|url=http://www.oecd-ilibrary.org/environment/water-consumption-and-sustainable-water-resources-management_9789264162648-en|title=Water Consumption and Sustainable Water Resources Management|access-date=26 April 2016|isbn=9789264162648 |publisher=OECD Library|date=25 March 1998}}</ref> The re-use and reclamation of water is also part of sustainability including downstream impacts on both surface waters and [[ground water]]s.<ref name=naumann>{{cite book|last=Naumann|first=Ruth|title=Sustainability|date=2011|publisher=Cengage Learning|location=North Shore, N.Z.|isbn=978-017021-034-8|pages=56–58|edition=1st}}</ref>

=== Sustainability assessment ===
Water footprint accounting has advanced substantially in recent years, however, water footprint analysis also needs [[sustainability assessment]] as its last phase.<ref name="Hoekstra-2011" /> One of the developments is to employ sustainable efficiency and equity ("Sefficiency in Sequity"), which present a comprehensive approach to assessing the sustainable use of water.<ref name="Haie-2018" /><ref>{{Cite book|last=Haie|first=Naim|url=https://link.springer.com/content/pdf/bfm%3A978-981-15-6284-6%2F1.pdf|title=Transparent Water Management Theory: Sefficiency in Sequity|publisher=Springer|year=2020}}</ref>

==Sectoral distributions of withdrawn water use==
Several nations estimate sectoral distribution of use of water withdrawn from surface and groundwater sources. For example, in Canada, in 2005, 42 billion m<sup>3</sup> of withdrawn water were used, of which about 38 billion m<sup>3</sup> were freshwater. Distribution of this use among sectors was: [[Environmental impact of electricity generation#Water usage|thermoelectric power generation]] 66.2%, manufacturing 13.6%, residential 9.0%, agriculture 4.7%, commercial and institutional 2.7%, water treatment and distribution systems 2.3%, mining 1.1%, and oil and gas extraction 0.5%.  The 38 billion m<sup>3</sup> of freshwater withdrawn in that year can be compared with the nation's annual freshwater yield (estimated as streamflow) of 3,472 billion m<sup>3</sup>.<ref>Statistics Canada.  2010.  Human activity and the environment.  Freshwater supply and demand in Canada.  Catalogue no. 16-201-X.</ref>  Sectoral distribution is different in many respects in the US, where agriculture accounts for about 39% of fresh water withdrawals, thermoelectric power generation 38%, industrial 4%, residential 1%, and mining (including oil and gas) 1%.<ref name=Maupin2014/>

Within the agricultural sector, withdrawn water use is for irrigation and for livestock.  Whereas all irrigation in the US (including loss in conveyance of irrigation water) is estimated to account for about 38 percent of US withdrawn freshwater use,<ref name=Maupin2014>Maupin, M. A. et al. 2014. Estimated use of water in the United States 2010.  U. S. Geological Survey Circular 1405. 55 pp.</ref> the irrigation water used for production of livestock feed and forage has been estimated to account for about 9 percent,<ref>Zering, K. D., T. J. Centner, D. Meyer, G. L. Newton, J. M. Sweeten and S. Woodruff. 2012. Water and land issues associated with animal agriculture: a U.S. perspective. CAST Issue Paper No. 50. Council for Agricultural Science and Technology, Ames, Iowa. 24 pp.</ref> and other withdrawn freshwater use for the livestock sector (for drinking, washdown of facilities, etc.) is estimated at about 0.7 percent.<ref name=Maupin2014/>  Because agriculture is a major user of withdrawn water, changes in the magnitude and efficiency of its water use are important.  In the US, from 1980 (when agriculture's withdrawn water use peaked) to 2010, there was a 23 percent reduction in agriculture's use of withdrawn water,<ref name=Maupin2014/> while US agricultural output increased by 49 percent over that period.<ref>{{cite web|url=http://www.ers.usda.gov/data-products/agricultural-productivity-in-the-us.aspx#28247|title=USDA ERS - Agricultural Productivity in the U.S.|website=www.ERS.USDA.gov|access-date=5 May 2017}}</ref>

In the US, irrigation water application data are collected in the quinquennial Farm and Ranch Irrigation Survey, conducted as part of the Census of Agriculture.  Such data indicate great differences in irrigation water use within various agricultural sectors.  For example, about 14 percent of corn-for-grain land and 11 percent of soybean land in the US are irrigated, compared with 66 percent of vegetable land, 79 percent of orchard land and 97 percent of rice land.<ref name=USDA2009>US Department of Agriculture.  2009. 2007 Census of agriculture. Farm and ranch irrigation survey (2008). Volume 3. Special Studies. Part 1. AC-07-SS-1. 177 pp. + appendices.</ref><ref>USDA. 2009. 2007 Census of agriculture. United States summary and State Data. Vol. 1. Geographic Area Series. Part 51. AC-07-A-51. 639 pp. + appendices.</ref>

==See also==
{{Portal|Environment|Ecology}}

{{columns-list|colwidth=22em|
* [[Carbon footprint]]
* [[Deficit irrigation]]
* [[Ecological footprint]]
* [[Runoff footprint]]
* [[Social metabolism]]
* [[Virtual water]]
* [[Water resource management]]
* [[Water resources]]
* [[Water scarcity]]
* [[Water positive]]
}}

==References==
{{Reflist | 2}}

==External links==
* [http://www.waterfootprint.org/ Water Footprint Network]
* [http://waterfootprint.org/en/resources/interactive-tools/personal-water-footprint-calculator/ Personal Water Footprint Calculator]
* [https://aermotorwindmill.com/pages/windmills-and-water-needs Amount of water needed per day for livestock and household use]

{{Water}}
{{Natural resources}}
{{Public health}}

{{DEFAULTSORT:Water Footprint}}
[[Category:Water]]
[[Category:Water resources management]]
[[Category:Water and the environment]]
[[Category:Environmental terminology]]
[[Category:Macroeconomic indicators]]
[[Category:Economic globalization]]
[[Category:Environmental indices]]