Virtual Water

1 HAMBURGER = 2,400 litres of water!

Whether it’s a steak, a sweater or a computer, water is not visible in the products we buy. Yet significant quantities of water are needed to make them. We define virtual water as the “water necessary to make a good”. Making a kilo of cereals for example, requires 1,300 litres of water. This water comes from various sources: ground water, water courses, rain or even soil humidity.

In the world, water is mainly used for agricultural purposes, in order to feed humans. That is why food is a good example of measuring virtual water. For instance, an animal protein-based diet demands 5.4 m³ of water a day. On the contrary, a vegetarian diet only requires 2.6 m³ of water per day.

You can calculate your water footprint the same way you can calculate your carbon footprint on the following website: www.waterfootprint.org

It is also possible to calculate a country’s water footprint, which is influenced by three different factors:

• total volume of consumption, which is directly linked to a country’s wealth. That partly explains why countries such as the United States, Spain or Switzerland, are at the top of the ranking,
• inhabitants’ lifestyle: a high meat diet significantly increases a country’s water footprint. A US citizen eats on average 120 kilos of meat per year, three times more than global average! Industrial goods consumption also plays an important role in the ranking,
• climate. In hot countries, evaporation and water consumption in the agricultural sector is particularly high. That is why some countries like Sudan (2,214 m³ per capita and per year), Senegal or Syria are at the top of the ranking. These poor countries, with unfavourable climatic conditions, more often than not have unsatisfactory agricultural practices which are costly to water.

             

Examples of water quantity necessary to make a product:

To produce one kilo of:	Water quantity needed:
Apple	700 L
Bread/Cereals	1 300 L
Egg	3 300 L
Pork	4 800 L
Beef	15 500 L

Source: UNESCO – IHE Institute for Water Education

 

Other examples :

 

To produce one kilo of:	Water quantity needed:
Plastic	1 à 2 L
Paper	500 L
Rayon fabric (viscose)	400 à 11 000  L
Cotton	5 263 L

 

Source: CNRS – Scientific dossier