Water Supply

So how much water does a Google search consume?

PUBLISHED : Sunday, 17 October, 2010, 12:00am
UPDATED : Sunday, 17 October, 2010, 12:00am

There are many names for it - virtual water, embedded water, embodied water, hidden water - but the concept is the same.

It is a calculation of how much water is used in the production and trade of food and consumer goods.

The idea of a water footprint was first created by Professor John Allan from King's College in London, who received the 2008 Stockholm Water Prize for his efforts.

For example, production of 1kg of wheat 'costs' 1,300 litres of virtual water while 1kg of beef costs around 15,000 litres.

'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,' Allan said. 'The concept of virtual water helps us realise how much water is needed to produce different goods and services.'

In order to calculate the water cost of a product, it is necessary to break down each step of production.

For example, half a kilogram of chicken costs more than 1,700 litres of water, which includes the water needed for the grain to feed the chicken as well as the irrigation water needed to grow the grain. A cup of milk costs 208 litres of water, which is used for raising and grazing cattle and then the processing and bottling costs of the milk.

Consumer goods also have a water footprint. Production of a pair of jeans uses more than 10,000 litres of water, while a medium-sized cotton shirt requires 4,100 litres of water.

The concept has even extended to non-tangible goods such as an internet search. According to Robert Osborne, an engineer at Black & Veatch, every time you use Google, 1/10th of a teaspoon of water is evaporated.