quantifies the water used in the production of a good or service

concept was developed by Professor John Anthony Allan

said to be ‘virtual’ because once the water is used, it is nolonger contained in the product (example: wheat)

a concept that is rather controversial and not universally accepted

3 colours of virtual waterBLUE – the volume of surface water or groundwaterthat has evaporated as a result of production.

GREEN – the volume of rainwater that has evaporated as a result of production.

GRAY - the volume of water that is polluted as a result of production. in all cases, water is ‘lost’ because it is no longer available

for other uses.

=

Approximately 50,000 liters

Approximately 140 liters

=

= 70 liters= 10 liters per sheet

= 2400 liters

= 3900 liters per kilogram

= 5000 liters per kilogram

= 1300 litersper kilogram

= 32 liters

= 400,000 liters

a country’s water footprint = virtual water import – virtual water export

can compliment carbon footprints & eco-footprints

makes a link between water consumption in one placeand the impacts felt by water systems elsewhereto accurately calculate water footprints, producttransparency is needed from manufacturers andgovernments

Netherlands: virtual water import for coffee …over 250 million cubic meters of virtual water are

exportedfrom South America EVERY YEAR!

why is this important?

places with less water can gain access to foods (and other products) with higher water requirements by importing them from areas with high rainfall and increasedaccess to water – this allows water-scarce regions to use their water resources more efficiently

UNESCO estimates that we have already reduced globaluse by 5% just by managing virtual water – it allows us to work as a global community to tackle water issues

it makes us think about water differently – a few liters ofwater are wasted when you take a long shower, but thousands of liters of water are wasted when you throwaway food (and other products)

Blue water – irrigation, energy use, fossil fuel consumption (water is used in the extraction

of fossil fuels)Green water – evaporation

Gray water – pollution through fertilizers

and pesticides

Blue water – processing of fibers, energy use,

fossil fuel consumptionGray water – pollution

through dyes and other chemicals

Blue water – manufacturing processes, energy use

Gray water – pollution through fabric treatments, additional dye and

other chemicals

Blue water – fossil fuel consumption, packaging, development of marketing materialsGray Water - ……

1 cotton t-shirt = 2700 liters of virtual water