Water Footprints and Virtual Water
Water footprints measure both the direct and indirect consumption, evaporation, and pollution of fresh water by the goods and services used by individuals, businesses, communities or nations. Indirect water use "hidden" or embedded in the production processes is known as virtual water.

The Water Footprint of Food

Water Footprints
Estimates of how much water is used in the consumption or production of a product or service require an analysis of the production details of the given commodity. As a result Water footprints have a geographical nature and similar crops or products may have different water footprints depending upon the region of origin and consumption. The water footprints of the various food items shown in the figure above are in terms of a global average. Notice also that in the text water footprints are given in terms of liters per kilogram while in the graphical display footprints are given in terms of liters per pound (.454 kg).

Using the Water Footprints of various products and services one can compose a virtual water budget for ones lifestyle or the practices of a organization, corporation, or even an entire nation. Online calculators can help individuals and organizations estimate their water footprint and identify important ways improve the efficiency of their use of environmental resources. Estimate your water personal footprint here.

The Water Footprint of Nations

"When the well's dry, we know the worth of water."
Benjamin Franklin, (1706-1790), Poor Richard's Almanac. Chief Seattle
The Water Footprint of Nations
Assessing the water footprint of a nation depends upon the consumption volume and patterns of consumers and on the water footprints of the consumed commodities. It also requires that the international flow of the virtual water hidden in various products traded between nations be mapped, as the footprint of a given commodity depends upon the details of its production (and thus it's place of origin.) The agricultural yields of a given region (growth conditions and water use efficiency) are key to these estimates.

Virtual Water Flow Between Nations

Click image to link to source: ;   Data derived from The Water Footprint of Humanity by Hoekstra and Mekonnen (2012).

The Water Footprint (Further Analysis)

Virtual water can be further understood by sub-dividing it into the following three categories:
1. Blue Water. Blue water is the volume of freshwater extracted from a groundwater or surface water reservoir and not returned.
2. Green Water. Green water is the volume of rain water consumed. This is a particularly useful concept in agriculture where it refers to the total rainwater used in evapotranspiration (from the fields) plus the water incorporated into the crops.
3. Grey Water. Grey water is the volume of freshwater necessary to provide for the assimilation of pollutants produced to natural background levels.

In addition Virtual Water consumption can be broken down according to the economic sectors or geographically to states and counties. Research into the use of the Water Footprint as a means of aiding citizens and policy makers in crafting sustainable water management approaches will continue. The Water Footprint Network is a great location to learn more about this concept and it's application.

Further Analysis of Virtual Water Use
   Select:                   Type of Virtual Water                   Economic Sectors                   Detailed US

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Human Footprint Maps
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Human Footprint Nasa 4
Human Footprint Nasa 4
Water footprint diagrams
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