Water Footprints of Nations: Water Use by People as a Function of Their Consumption Pattern

Abstract

The water footprint shows the extent of water use in relation to consumption of people. The water footprint of a country is
defined as the volume of water needed for the production of the goods and services consumed by the inhabitants of the country.
The internal water footprint is the volume of water used from domestic water resources; the external water footprint is the
volume of water used in other countries to produce goods and services imported and consumed by the inhabitants of the country.
The study calculates the water footprint for each nation of the world for the period 1997–2001. The USA appears to have an
average water footprint of 2480m3/cap/yr, while China has an average footprint of 700m3/cap/yr. The global average water footprint is 1240m3/cap/yr. 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 meat consumption); climate (growth conditions); and
agricultural practice (water use efficiency).

Full text

Water Resour Manage (2007) 21:35–48
DOI 10.1007/s11269-006-9039-x
ORIGINAL ARTICLE
Water footprints of nations: Water use by people as a
function of their consumption pattern
A. Y. Hoekstra ·A. K. Chapagain
Received: 18 January 2005 / Accepted: 12 October 2005
C
Springer Science +Business Media B.V. 2006
Abstract The water footprint shows the extent of water use in relation to consumption
of people. The water footprint of a country is defined as the volume of water needed for
the production of the goods and services consumed by the inhabitants of the country. The
internal water footprint is the volume of water used from domestic water resources; the
external water footprint is the volume of water used in other countries to produce goods and
services imported and consumed by the inhabitants of the country. The study calculates the
water footprint for each nation of the world for the period 1997–2001. The USA appears to
have an average water footprint of 2480 m3/cap/yr, while China has an average footprint of
700 m3/cap/yr. The global average water footprint is 1240 m3/cap/yr. 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 meat consumption);
climate (growth conditions); and agricultural practice (water use efficiency).
Keywords Water footprint .Consumption .Virtual water .Indicators .Water use
efficiency .External water dependency
Introduction
Databases on water use traditionally show three columns of water use: water withdrawals
in the domestic, agricultural and industrial sector respectively (Gleick, 1993; Shiklomanov,
2000; FAO, 2003). A water expert being asked to assess the water demand in a particular
country will generally add the water withdrawals for the different sectors of the economy.
Although useful information, this does not tell much about the water actually needed by the
people in the country in relation to their consumption pattern. The fact is that many goods
A. Y. Hoekstra ()
University of Twente, Enschede, The Netherlands
e-mail: a.y.hoekstra@utwente.nl
A. K. Chapagain
UNESCO-IHE, Delft, The Netherlands
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36 Water Resour Manage (2007) 21:35–48
consumed by the inhabitants of a country are produced in other countries, which means that it
can happen that the real water demand of a population is much higher than the national water
withdrawals do suggest. The reverse can be the case as well: national water withdrawals
are substantial, but a large amount of the products are being exported for consumption
elsewhere.
In 2002, the water footprint concept was introduced in order to have a consumption-
based indicator of water use that could provide useful information in addition to the tra-
ditional production-sector-based indicators of water use (Hoekstra and Hung, 2002). The
water footprint of a nation is defined as the total volume of freshwater that is used to pro-
duce the goods and services consumed by the people of the nation. Since not all goods
consumed in one particular country are produced in that country, the water footprint consists
of two parts: use of domestic water resources and use of water outside the borders of the
country.
The water footprint has been developed in analogy to the ecological footprint concept
as was introduced in the 1990s (Rees, 1992; Wackernagel and Rees, 1996; Wackernagel
et al., 1997). The ‘ecological footprint’ of a population represents the area of productive
land and aquatic ecosystems required to produce the resources used, and to assimilate the
wastes produced, by a certain population at a specified material standard of living, wherever
on earth that land may be located. Whereas the ‘ecological footprint’ thus quantifies the area
needed to sustain people’s living, the ‘water footprint’ indicates the water required to sustain
a population.
The water footprint concept is closely linked to the virtual water concept. Virtual water
is defined as the volume of water required to produce a commodity or service. The concept
was introduced by Allan in the early 1990s (Allan, 1993, 1994) when studying the option
of importing virtual water (as opposed to real water) as a partial solution to problems of
water scarcity in the Middle East. Allan elaborated on the idea of using virtual water import
(coming along with food imports) as a tool to release the pressure on the scarcely available
domestic water resources. Virtual water import thus becomes an alternative water source,
next to endogenous water sources. Imported virtual water has therefore also been called
‘exogenous water’ (Haddadin, 2003).
When assessing the water footprint of a nation, it is essential to quantify the flows of virtual
water leaving and entering the country. If one takes the use of domestic water resources as
a starting point for the assessment of 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.
The objective of this study is to assess and analyse the water footprints of nations. The study
builds on two earlier studies. Hoekstra and Hung (2002, 2005) have quantified the virtual
water flows related to the international trade of crop products. Chapagain and Hoekstra (2003)
have done a similar study for livestock and livestock products. The concerned time period in
these two studies is 1995–1999. The present study takes the period of 1997–2001 and refines
the earlier studies by making a number of improvements and extensions.
Method
A nation’s water footprint has two components, the internal and the external water footprint.
The internal water footprint (IWFP) is defined as the use of domestic water resources to
produce goods and services consumed by inhabitants of the country. It is the sum of the total
water volume used from the domestic water resources in the national economy minus the
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Water Resour Manage (2007) 21:35–48 37
volume of virtual water export to other countries insofar related to export of domestically
produced products:
IWFP =AWU +IWW +DWW −VWEdom (1)
Here, AWU is the agricultural water use, taken equal to the evaporative water demand of
the crops; IWW and DWW are the water withdrawals in the industrial and domestic sectors
respectively; and VWEdom is the virtual water export to other countries insofar related to
export of domestically produced products. The agricultural water use includes both effective
rainfall (the portion of the total precipitation which is retained by the soil and used for crop
production) and the part of irrigation water used effectively for crop production. Here we do
not include irrigation losses in the term of agricultural water use assuming that they largely
return to the resource base and thus can be reused.
The external water footprint of a country (EWFP) is defined as the annual volume of water
resources used in other countries to produce goods and services consumed by the inhabitants
of the country concerned. It is equal to the so-called virtual water import into the country
minus the volume of virtual water exported to other countries as a result of re-export of
imported products.
EWFP =VWI −VWEre−export (2)
Both the internal and the external water footprint include the use of blue water (ground and
surface water) and the use of green water (moisture stored in soil strata).
The use of domestic water resources comprises water use in the agricultural, industrial and
domestic sectors. For the latter two sectors we have used data from AQUASTAT (FAO, 2003).
Though significant fractions of domestic and industrial water withdrawals do not evaporate
but return to either the groundwater or surface water system, these return flows are generally
polluted, so that they have been included in the water footprint calculations. The total volume
of water use in the agricultural sector has been calculated in this study based on the total
volume of crop produced and its corresponding virtual water content. For the calculation of
the virtual water content of crop and livestock products we have used the methodology as
described in Chapagain and Hoekstra (2004). In summary, the virtual water content (m3/ton)
of primary crops has been calculated based on crop water requirements and yields. Crop water
requirement have been calculated per crop and per country using the methodology developed
by FAO (Allen et al., 1998). The virtual water content of crop products is calculated based on
product fractions (ton of crop product obtained per ton of primary crop) and value fractions
(the market value of one crop product divided by the aggregated market value of all crop
products derived from one primary crop). The virtual water content (m3/ton) of live animals
has been calculated based on the virtual water content of their feed and the volumes of
drinking and service water consumed during their lifetime. We have calculated the virtual
water content for eight major animal categories: beef cattle, dairy cows, swine, sheep, goats,
fowls/poultry (meat purpose), laying hens and horses. The calculation of the virtual water
content of livestock products is again based on product fractions and value fractions.
Virtual water flows between nations have been calculated by multiplying commodity trade
flows by their associated virtual water content:
VWF[ne,ni,c]=CT[ne,ni,c]×VWC[ne,c] (3)
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38 Water Resour Manage (2007) 21:35–48
in which VWF denotes the virtual water flow (m3yr−1) from exporting country neto importing
country nias a result of trade in commodity c;CT the commodity trade (ton yr−1) from the
exporting to the importing country; and VWC the virtual water content (m3ton−1)ofthe
commodity, which is defined as the volume of water required to produce the commodity in
the exporting country. We have taken into account the trade between 243 countries for which
international trade data are available in the Personal Computer Trade Analysis System of the
International Trade Centre, produced in collaboration with UNCTAD/WTO. It covers trade
data from 146 reporting countries disaggregated by product and partner countries (ITC, 2004).
We have carried out calculations for 285 crop products and 123 livestock products. The virtual
water content of an industrial product can be calculated in a similar way as described earlier
for agricultural products. There are however numerous categories of industrial products with
a diverse range of production methods and detailed standardised national statistics related to
the production and consumption of industrial products are hard to find. As the global volume
of water used in the industrial sector is only 716 Gm3/yr (≈10% of total global water use),
we have – per country – simply calculated an average virtual water content per dollar added
value in the industrial sector (m3/US$) as the ratio of the industrial water withdrawal (m3/yr)
in a country to the total added value of the industrial sector (US$ /yr), which is a component
of the Gross Domestic Product.
Water needs by product
The total volume of water used globally for crop production is 6390 Gm3/yr at field level. Rice
has the largest share in the total volume water used for global crop production. It consumes
about 1359 Gm3/yr, which is about 21% of the total volume of water used for crop production
at field level. The second largest water consumer is wheat (12%). The contribution of some
major crops to the global water footprint insofar related to food consumption is presented in
Figure 1. Although the total volume of the world rice production is about equal to the wheat
production, rice consumes much more water per ton of production. The difference is due
Cassava
2%
Natural Rubber
1%
Oil Palm Fruit
2%
Groundnuts in Shell
2%
Rice, Paddy
21%
Other
37%
Other minor crops
26%
Potatoes
1%
Cocoa Beans
1%Wheat
12%
Maize
9%
Soybeans
4%
Sugar Cane
3%
Seed Cotton
3%
Barley
3% Sorghum
3% Coconuts
2%
Millet
2%
Coffee, Green
2%
Fig. 1 Contribution of different crops to the global water footprint
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Water Resour Manage (2007) 21:35–48 39
to the higher evaporative demand for rice production. As a result, the global average virtual
water content of rice (paddy) is 2291 m3/ton and for wheat 1334 m3/ton.
The virtual water content of rice (broken) that a consumer buys in the shop is about
3420 m3/ton. This is larger than the virtual water content of paddy rice as harvested from the
field because of the weight loss if paddy rice is processed into broken rice. The virtual water
content of some selected crop and livestock products for a number of selected countries are
presented in Table 1.
In general, livestock products have a higher virtual water content than crop products. This
is because a live animal consumes a lot of feed crops, drinking water and service water in its
lifetime before it produces some output. We consider here an example of beef produced in an
industrial farming system. It takes in average 3 years before it is slaughtered to produce about
200 kg of boneless beef. It consumes nearly 1300kg of grains (wheat, oats, barley, corn, dry
peas, soybean meal and other small grains), 7200 kg of roughages (pasture, dry hay, silage
and other roughages), 24 cubic meter of water for drinking and 7 cubic meter of water for
servicing. This means that to produce one kilogram of boneless beef, we use about 6.5 kg of
grain, 36 kg of roughages, and 155 l of water (only for drinking and servicing). Producing the
volume of feed requires about 15340 l of water in average. With every step of food processing
we loose part of the material as a result of selection and inefficiencies. The higher we go up
in the product chain, the higher will be the virtual water content of the product. For example,
the global average virtual water content of maize, wheat and rice (husked) is 900, 1300 and
3000 m3/ton respectively, whereas the virtual water content of chicken meat, pork and beef
is 3900, 4900 and 15500 m3/ton respectively. However, the virtual water content of products
strongly varies from place to place, depending upon the climate, technology adopted for
farming and corresponding yields.
The units used so far to express the virtual water content of various products are in terms
of cubic meters of water per ton of the product. A consumer might be more interested to
know how much water it consumes per unit of consumption. One cup of coffee requires
for instance 140 l of water in average, one hamburger 2400 l and one cotton T-shirt 2000l
(Table 2).
The global average virtual water content of industrial products is 80l per US$ . In the
USA, industrial products take nearly 100 l per US$ . In Germany and the Netherlands, average
virtual water content of industrial products is about 50 l per US$ . Industrial products from
Japan, Australia and Canada take only 10–15 l per US$ . In world’s largest developing nations,
China and India, the average virtual water content of industrial products is 20–25l per US$ .
Water footprints of nations
The global water footprint is 7450 Gm3/yr, which is 1240 m3/cap/yr in average. In absolute
terms, India is the country with the largest footprint in the world, with a total footprint of
987 Gm3/yr. However, while India contributes 17% to the global population, the people in
India contribute only 13% to the global water footprint. On a relative basis, it is the people
of the USA that have the largest water footprint, with 2480m3/yr per capita, followed by
the people in south European countries such as Greece, Italy and Spain (2300–2400 m3/yr
per capita). High water footprints can also be found in Malaysia and Thailand. At the other
side of the scale, the Chinese people have a relatively low water footprint with an average of
700 m3/yr per capita. The average per capita water footprints of nations are shown in Figure 2.
The data are shown in Table 3 for a few selected countries.
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40 Water Resour Manage (2007) 21:35–48
Table 1 Average virtual water content of some selected products for a number of selected countries (m3/ton)
USA China India Russia Indonesia Australia Brazil Japan Mexico Italy Netherlands World average∗
Rice (paddy) 1275 1321 2850 2401 2150 1022 3082 1221 2182 1679 2291
Rice (husked) 1656 1716 3702 3118 2793 1327 4003 1586 2834 2180 2975
Rice (broken) 1903 1972 4254 3584 3209 1525 4600 1822 3257 2506 3419
Wheat 849 690 1654 2375 1588 1616 734 1066 2421 619 1334
Maize 489 801 1937 1397 1285 744 1180 1493 1744 530 408 909
Soybeans 1869 2617 4124 3933 2030 2106 1076 2326 3177 1506 1789
Sugar cane 103 117 159 164 141 155 120 171 175
Cotton seed 2535 1419 8264 4453 1887 2777 2127 3644
Cotton lint 5733 3210 18694 10072 4268 6281 4812 8242
Barley 702 848 1966 2359 1425 1373 697 2120 1822 718 1388
Sorghum 782 863 4053 2382 1081 1609 1212 582 2853
Coconuts 749 2255 2071 1590 1954 2545
Millet 2143 1863 3269 2892 1951 3100 4534 4596
Coffee (green) 4864 6290 12180 17665 13972 28119 17373
Coffee (roasted) 5790 7488 14500 21030 16633 33475 20682
Tea (made) 11110 7002 3002 9474 6592 4940 9205
Beef 13193 12560 16482 21028 14818 17112 16961 11019 37762 21167 11681 15497
Pork 3946 2211 4397 6947 3938 5909 4818 4962 6559 6377 3790 4856
Goat meat 3082 3994 5187 5290 4543 3839 4175 2560 10252 4180 2791 4043
Sheep meat 5977 5202 6692 7621 5956 6947 6267 3571 16878 7572 5298 6143
Chicken meat 2389 3652 7736 5763 5549 2914 3913 2977 5013 2198 2222 3918
Eggs 1510 3550 7531 4919 5400 1844 3337 1884 4277 1389 1404 3340
Milk 695 1000 1369 1345 1143 915 1001 812 2382 861 641 990
Milk powder 3234 4648 6368 6253 5317 4255 4654 3774 11077 4005 2982 4602
Cheese 3457 4963 6793 6671 5675 4544 4969 4032 11805 4278 3190 4914
Leather (bovine) 14190 13513 17710 22575 15929 18384 18222 11864 40482 22724 12572 16656
∗For the primary crops, world averages have been calculated as the ratio of the global water use for the production of a crop to the global production
volume. For processed products, the global averages have been calculated as the ratio of the global virtual water trade volume to the global product trade
volume.
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Water Resour Manage (2007) 21:35–48 41
Table 2 Global average virtual water content of some selected products, per unit of product
Product Virtual water content (litres)
1 glass of beer (250 ml) 75
1 glass of milk (200 ml) 200
1 cup of coffee (125 ml) 140
1 cup of tea (250 ml) 35
1 slice of bread (30 g) 40
1 slice of bread (30 g) with cheese(10g) 90
1 potato (100 g) 25
1 apple (100 g) 70
1 cotton T-shirt (250g) 2000
1 sheet of A4-paper (80 g/m2)10
1 glass of wine (125 ml) 120
1 glass of apple juice (200 ml) 190
1 glass of orange juice (200 ml) 170
1 bag of potato crisps (200 g) 185
1 egg (40 g) 135
1 hamburger (150 g) 2400
1 tomato (70 g) 13
1 orange (100 g) 50
1 pair of shoes (bovine leather) 8000
1 microchip (2 g) 32
Fig. 2 Averagenational water footprint per capita (m3/capita/yr). Green means that the nation’s water footprint
is equal to or smaller than global average. Countries with red have a water footprint beyond the global average
The size of the global water footprint is largely determined by the consumption of food
and other agricultural products (Figure 3). The estimated contribution of agriculture to the
total water use (6390 Gm3/yr) is even bigger than suggested by earlier statistics due to the
inclusion of green water use (use of soil water). If we include irrigation losses, which globally
add up to about 1590 Gm3/yr (Chapagain and Hoekstra, 2004), the total volume of water used
in agriculture becomes 7980 Gm3/yr. About one third of this amount is blue water withdrawn
for irrigation; the remaining two thirds is green water (soil water).
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
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42 Water Resour Manage (2007) 21:35–48
Table 3 Composition of the water footprint for some selected countries. Period: 1997–2001
Use of domestic water resources Use of foreign water resources Water footprint by consumption category
Agricultural goods Industrial goods
Crop evapotranspiration∗Industrial water withdrawal For national consumption Domestic water
Domestic For re-export Water footprint Internal Internal External Internal External
water For national For national Agricultural Industrial of imported water water water water water
withdrawal consumption For export consumption For export goods goods products Total Per capita footprint footprint footprint footprint footprint
Country Population (Gm3/yr) (Gm3/yr) (Gm3/yr) (Gm3/yr) (Gm3/yr) (Gm3/yr) (Gm3/yr) (Gm3/yr) (Gm3/yr) (m3/cap/yr) (m3/cap/yr) (m3/cap/yr) (m3/cap/yr) (m3/cap/yr) (m3/cap/yr)
Australia 19071705 6.51 14.03 68.67 1.229 0.12 0.78 4.02 4.21 26.56 1393 341 736 41 64 211
Bangladesh 129942975 2.12 109.98 1.38 0.344 0.08 3.71 0.34 0.13 116.49 896 16 846 29 3 3
Brazil 169109675 11.76 195.29 61.01 8.666 1.63 14.76 3.11 5.20 233.59 1381 70 1155 87 51 18
Canada 30649675 8.55 30.22 52.34 11.211 20.36 7.74 5.07 22.62 62.80 2049 279 986 252 366 166
China 1257521250 33.32 711.10 21.55 81.531 45.73 49.99 7.45 5.69 883.39 702 26 565 40 65 6
Egypt 63375735 4.16 45.78 1.55 6.423 0.66 12.49 0.64 0.49 69.50 1097 66 722 197 101 10
France 58775400 6.16 47.84 34.63 15.094 12.80 30.40 10.69 31.07 110.19 1875 105 814 517 257 182
Germany 82169250 5.45 35.64 18.84 18.771 13.15 49.59 17.50 38.48 126.95 1545 66 434 604 228 213
India 1007369125 38.62 913.70 35.29 19.065 6.04 13.75 2.24 1.24 987.38 980 38 907 14 19 2
Indonesia 204920450 5.67 236.22 22.62 0.404 0.06 26.09 1.58 2.74 269.96 1317 28 1153 127 2 8
Italy 57718000 7.97 47.82 12.35 10.133 5.60 59.97 8.69 20.29 134.59 2332 138 829 1039 176 151
Japan 126741225 17.20 20.97 0.40 13.702 2.10 77.84 16.38 4.01 146.09 1153 136 165 614 108 129
Jordan 4813708 0.21 1.45 0.07 0.035 0.00 4.37 0.21 0.22 6.27 1303 44 301 908 7 43
Mexico 97291745 13.55 81.48 12.26 2.998 1.13 35.09 7.05 7.94 140.16 1441 139 837 361 31 72
Netherlands 15865250 0.44 0.50 2.51 2.562 2.20 9.30 6.61 52.84 19.40 1223 28 31 586 161 417
Pakistan 136475525 2.88 152.75 7.57 1.706 1.28 8.55 0.33 0.67 166.22 1218 21 1119 63 12 2
Russia 145878750 14.34 201.26 8.96 13.251 34.83 41.33 0.80 3.94 270.98 1858 98 1380 283 91 5
South Africa 42387403 2.43 27.32 6.05 1.123 0.40 7.18 1.42 2.10 39.47 931 57 644 169 26 33
Thailand 60487800 1.83 120.17 38.49 1.239 0.55 8.73 2.49 3.90 134.46 2223 30 1987 144 20 41
United Kingdom 58669403 2.21 12.79 3.38 6.673 1.46 34.73 16.67 12.83 73.07 1245 38 218 592 114 284
USA 280343325 60.80 334.24 138.96 170.777 44.72 74.91 55.29 45.62 696.01 2483 217 1192 267 609 197
Global total/avg. 5994251631 344 5434 957 476 240 957 240 427 7452 1243 57 907 160 79 40
∗Includes both blue and green water use in agriculture
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Water Resour Manage (2007) 21:35–48 43
Domestic water c onsumption
5%
Industrial products
6%
Agricultur al products
73%
External water footprint
16 %
Industrial pro ducts
3%
Agricultural products
13%
Internal water footprint
84.0%
Fig. 3 Contribution of different consumption categories to the global water footprint, with a distinction
between the internal and external footprint
low meat consumption); climate (growth conditions); and agricultural practice (water use
efficiency). In rich countries, people generally consume more goods and services, which
immediately translates into increased water footprints. But it is not consumption volume
alone that determines the water demand of people. The composition of the consumption
package is relevant too, because some goods in particular require a lot of water (bovine meat,
rice). In many poor countries it is a combination of unfavourable climatic conditions (high
evaporative demand) and bad agricultural practice (resulting in low water productivity) that
contributes to a high water footprint. Underlying factors that contribute to bad agricultural
practice and thus high water footprints are the lack of proper water pricing, the presence
of subsidies, the use of water inefficient technology and lack of awareness of simple water
saving measures among farmers.
The influence of the various determinants varies from country to country. The water
footprint of the USA is high (2480 m3/cap/yr) partly because of large meat consumption per
capita and high consumption of industrial products. The water footprint of Iran is relatively
high (1624 m3/cap/yr) partly because of low yields in crop production and partly because
of high evapotranspiration. In the USA the industrial component of the water footprint is
806 m3/cap/yr whereas in Iran it is only 24 m3/cap/yr.
The aggregated external water footprints of nations in the world constitute 16% of the
total global water footprint (Figure 3). However, the share of the external water footprint
strongly varies from country to country. Some African countries, 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 contributing 50–80% to the total water
footprint. The agricultural products that contribute most to the external water footprints of
nations are: bovine meat, soybean, wheat, cocoa, rice, cotton and maize.
Eight countries – India, China, the USA, the Russian Federation, Indonesia, Nigeria,
Brazil and Pakistan – together contribute fifty percent to the total global water footprint.
India (13%), China (12%) and the USA (9%) are the largest consumers of the global water
resources (Figure 4).
Both the size of the national water footprint and its composition differs between countries
(Figure 5). On the one end we see China with a relatively low water footprint per capita, and on
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44 Water Resour Manage (2007) 21:35–48
Mexico
2%
Thailand
2%
Other
44%
Other
58%
Japan
2%
Pakistan
2%
Brazil
3%
Nigeria
3%
Indonesia
4%
Russian Federation
4%
USA
9%
China
12%
Indi a
13%
Fig. 4 Contribution of major consumers to the global water footprint
0
500
1000
1500
2000
2500
3000
anihC
aidnI
napaJ
natsikaP
aisenodnI
lizarB
oci
x
eM
aissuR
airegiN
dnaliahT
ylatI
ASU
m( tnirptoof retaW 3)ry/pac/
Domestic water consumption Industrial goods Agricultural goods
Fig. 5 The national water footprint per capita and the contribution of different consumption categories for
some selected countries
the other end the USA. In the rich countries consumption of industrial goods has a relatively
large contribution to the total water footprint if compared with developing countries. The
water footprints of the USA, China, India and Japan are presented in more detail in Figure 6.
The contribution of the external water footprint to the total water footprint is very large in
Japan if compared to the other three countries. The consumption of industrial goods very
significantly contributes to the total water footprint of the USA (32%), but not in India
(2%).
Conclusion
The global water footprint is 7450 Gm3/yr, which is in average 1240 m3/cap/yr. The differ-
ences between countries are large: the USA has an average water footprint of 2480m3/cap/yr
whereas China has an average water footprint of 700m3/cap/yr. There are four most im-
portant direct factors explaining high water footprints. A first factor is the total volume of
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Water Resour Manage (2007) 21:35–48 45
Fig. 6 Details of the water footprints of the USA, China India and Japan. Period: 1997–2001
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46 Water Resour Manage (2007) 21:35–48
consumption, which is generally related to gross national income of a country. This partially
explains the high water footprints of for instance the USA, Italy and Switzerland. A second
factor behind a high water footprint can be that people have a water-intensive consump-
tion pattern. Particularly high consumption of meat significantly contributes to a high water
footprint. This factor partially explains the high water footprints of countries such as the
USA, Canada, France, Spain, Portugal, Italy and Greece. The average meat consumption in
the United States is for instance 120 kg/yr, more than three times the world-average meat
consumption. Next to meat consumption, high consumption of industrial goods significantly
contributes to the total water footprints of rich countries. The third factor is climate. In re-
gions with a high evaporative demand, the water requirement per unit of crop production is
relatively large. This factor partially explains the high water footprints in countries such as
Senegal, Mali, Sudan, Chad, Nigeria and Syria. A fourth factor that can explain high water
footprints is water-inefficient agricultural practice, which means that water productivity in
terms of output per drop of water is relatively low. This factor partly explains the high water
footprints of countries such as Thailand, Cambodia, Turkmenistan, Sudan, Mali and Nigeria.
In Thailand for instance, rice yields averaged 2.5ton/ha in the period 1997–2001, while the
global average in the same period was 3.9ton/ha.
Reducing water footprints can be done in various ways. A first way is to break the seem-
ingly obvious link between economic growth and increased water use, for instance by adopt-
ing production techniques that require less water per unit of product. Water productivity in
agriculture can be improved for instance by applying advanced techniques of rainwater har-
vesting and supplementary irrigation. A second way of reducing water footprints is to shift
to consumptions patterns that require less water, for instance by reducing meat consumption.
However, it has been debated whether this is a feasible road to go, since the world-wide
trend has been that meat consumption increases rather than decreases. Probably a broader
and subtler approach will be needed, where consumption patterns are influenced by pricing,
awareness raising, labelling of products or introduction of other incentives that make people
change their consumption behaviour. Water costs are generally not well reflected in the price
of products due to the subsidies in the water sector. Besides, the general public is – although
often aware of energy requirements – hardly aware of the water requirements in producing
their goods and services.
A third method that can be used – not yet broadly recognized as such – is to shift production
from areas with low water-productivity to areas with high water productivity, thus increasing
global water use efficiency (Chapagain et al., 2005a). For instance, Jordan has successfully
externalised its water footprint by importing wheat and rice products from the USA, which
has higher water productivity than Jordan.
The water footprint of a nation is an indicator of water use in relation to the consumption
volume and pattern of the people. As an aggregated indicator it shows the total water require-
ment of a nation, a rough measure of the impact of human consumption on the natural water
environment. More information about the precise components and characteristics of the total
water footprint will be needed, however, before one can make a more balanced assessment
of the effects on the natural water systems. For instance, one has to look at what is blue
versus green water use, because use of blue water often affects the environment more than
green water use. Also it is relevant to consider the internal versus the external water foot-
print. Externalising the water footprint for instance means externalising the environmental
impacts. Also one has to realise that some parts of the total water footprint concern use of
water for which no alternative use is possible, while other parts relate to water that could
have been used for other purposes with higher added value. There is a difference for instance
between beef produced in extensively grazed grasslands of Botswana (use of green water
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Water Resour Manage (2007) 21:35–48 47
without alternative use) and beef produced in an industrial livestock farm in the Netherlands
(partially fed with imported irrigated feed crops).
The current study has focused on the quantification of consumptive water use, i.e. the
volumes of water from groundwater, surface water and soil water that evaporate. The effect
of water pollution was accounted for to a limited extent by including the (polluted) return
flows in the domestic and industrial sector. The calculated water footprints thus consists of
two components: consumptive water use and wastewater production. The effect of pollution
has been underestimated however in the current calculations of the national water footprints,
because one cubic metre of wastewater should not count for one, because it generally pollutes
much more cubic metres of water after disposal (various authors have suggested a factor of
ten to fifty). The impact of water pollution can be better assessed by quantifying the dilution
water volumes required to dilute waste flows to such extent that the quality of the water
remains below agreed water quality standards. We have shown this in a case study for the
water footprints of nations related to cotton consumption (Chapagain et al., 2005b).
International water dependencies are substantial and are likely to increase with continued
global trade liberalisation. Today, 16% of global water use is not for producing products
for domestic consumption but for making products for export. Considering this substantial
percentage and the upward trend, we suggest that future national and regional water policy
studies should include an analysis of international or interregional virtual water flows.
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