Alongside the now-famous Carbon-footprint is the concern over its lesser known but equally woeful sibling "Water-Footprint".
Water-Footprint is an indicator of water use that includes both direct and indirect water usage by a consumer or producer.The water footprint of an individual, community or business is defined as the total volume of freshwater that is used to produce the goods and services consumed by the individual or community or produced by the business.
History
The water footprint concept was introduced in 2002 by A.Y. Hoekstra from UNESCO-IHE as an alternative indicator of water use (Report as pdf)*.
The Colours of water-footprint
A water footprint consists of three components: the blue, green and grey water footprint.
The blue water footprint is the volume of freshwater that evaporated from the global blue water resources (surface water and ground water) to produce the goods and services consumed by the individual or community.
The green water footprint is the volume of water evaporated from the global green water resources (rainwater stored in the soil as soil moisture).
The grey water footprint is the volume of polluted water that associates with the production of all goods and services for the individual or community.
The global average Water Footprint is 1240 m³ water/person/year.
It is approximated that:
900 lit produce 1kg of maize
1350 lit produce 1kg of wheat
16000 lit produce 1kg of beef etc. (available on www.waterfootprint.org)
Criticism
The parameters used for calculating water-footprint have come under scrutiny and may not be adequately argumentative. For example the 140 litres required for production of one cup of coffee might be of no harm to water resources as its cultivation occurs mainly in humid areas. Nevertheless, the figures suggest the sum of water quantities as an environmental concern, which may not be supported by research.
Further Reading/Information
http://en.wikipedia.org/wiki/Water_footprint
http://www.waterfootprint.org
* Hoekstra, A.Y. (2003) (ed) Virtual water trade: Proceedings of the International Expert Meeting on Virtual Water Trade, IHE Delft, the Netherlands
princetonwaterwatch.wordpress.com 
