A water footprint is the total virtual water content of a product consumed by an individual, business, town etc. The footprint comprises:

Blue water: water withdrawn from groundwater or surface water sources;

Green water: water evaporated from soil moisture supplemented by rainfall;

Grey water: the polluted volume of blue water returned after production.

W ater footprints have been calculated for a number of “water intensive” products such as:

Manufacture of a cotton shirt takes 2,900 litres of water to grow the cotton

A 350ml tin of Coco Cola requires an average of 200 litres to grow and process the sugar

A pair of shoes takes 8,000 litres to grow, feed the cow and process the skin to make leather

16,000 litres of water is required to feed and grow the cattle to make 1 kilo of beef.

T he concept of the water footprint could be developed to take account of the life cycle of the product. This need not necessarily be developed to the same extent as the examples presented, but this would need to be explored on a case by case basis. A water footprint per facility could also be produced. The components could however be defined in a similar way as to the approach of the carbon footprint in order to:

Quantify the most water intensive parts of the business within site operations

Quantify the most water intensive parts of the business within the supply chain

Identify differences between countries due to climate and other factors:

Water rights and legal obligations

Which operations are in water or ecologically stressed areas

Water infrastructure and continuity of quantity and quality

Impact on local communities

The water/ energy relationship

Permissible wastewater discharges

Risks to the supply chain

Risks (and opportunities) to products

Set a benchmark from which future targets can be set

Develop contingency plans to respond to water risks, such as supply disruptions, more stringent regulations, increased costs