Water Footprint

Water use

Water use can mean the amount of water used by a household or a country, or the amount used for a given task or for the production of a given quantity of some product or crop. The term "water footprint" is often used to refer to the amount of water used by an individual, community, business, or nation.

World water use has been growing rapidly in the last hundred years (see graph from New Scientist article). From 1900 to 2000, water use for agriculture went from about 500 to 2,500 cubic kilometers per year, while total use rose from around 600 to more than 3,000 cubic kilometres per year. Agriculture uses 70% of water resources.

In the U.S, the typical single family home uses about 69.3 gallons (262 litres) of water per day (2008 estimate). This includes (in decreasing order) toilet use, washing machine use, showers, baths, faucet use, and leaks.

Water footprint

The water footprint of an individual, community or business is defined as the total volume of freshwater used to produce the goods and services consumed by the individual or community or produced by the business. Water use is measured in water volume consumed (evaporated) and/or polluted per unit of time. A water footprint can be calculated for any well-defined group of consumers (e.g., an individual, family, village, city, province, state or nation) or producers (e.g., a public organization, private enterprise or economic sector). The water footprint is a geographically explicit indicator, not only showing volumes of water use and pollution, but also the locations.

The water footprint of a country is related to what its people eat. In 1993, Professor John Allan (2008 Stockholm Water Prize Laureate), strikingly demonstrated this by introducing the "virtual water" concept, which measures how water is embedded in the production and trade of food and other products. For example, it a common thought that the water involved in a cup of coffee is just the water in the cup. There is actually 140 litres of water involved. The 140 litres of water is the amount of water that was used to grow, produce, package, and ship the coffee beans. A hamburger needs an estimated 2,400 litres of water. This hidden water is technically called virtual water. Therefore, eating a lot of meat means a large water footprint. The more food comes from irrigated land, the larger is the water footprint.

What is the Ecological Footprint?

Human activities  consume resources and produce waste, and as our populations grow and global consumption increases, it is essential that we measure nature’s capacity to meet these demands. The Ecological Footprint has emerged as one of the world’s leading measures of human demand on nature. Simply put, Ecological Footprint Accounting addresses whether the planet is large enough to keep up the demands of humanity.

The Footprint represents two sides of a balance sheet. On the asset side, biocapacity represents the planet’s biologically productive land areas including our forests, pastures, cropland and fisheries. These areas, especially if left unharvested, can also absorb much of the waste we generate, especially our carbon emissions.

Biocapacity can then be compared with humanity’s demand on nature: our Ecological Footprint. The Ecological Footprint represents the productive area required to provide the renewable resources humanity is using and to absorb its waste.  The productive area currently occupied by human infrastructure is also included in this calculation, since built-up land is not available for resource regeneration.
It now takes the Earth one year and six months to regenerate what we use in a year.

We maintain this overshoot by liquidating the Earth’s resources. Overshoot is a vastly underestimated threat to human well-being and the health of the planet, and one that is not adequately addressed.

By measuring the Footprint of a population—an individual, city, business, nation, or all of humanity—we can assess our pressure on the planet, which helps us manage our ecological assets more wisely and take personal and collective action in support of a world where humanity lives within the Earth’s bounds.

Conceived in 1990 by Mathis Wackernagel and William Rees at the University of British Columbia, the Ecological Footprint is now in wide use by scientists, businesses, governments, agencies, individuals, and institutions working to monitor ecological resource use and advance sustainable development.

Visit http://www.footprintnetwork.org
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