What is a water footprint?
We consume much more water than we think. Everything we use, wear, buy, sell and eat takes water to make.
The water footprint shows the total volume of fresh water consumed to produce each of the goods and services we use. It can be calculated for a single process, such as growing wheat, for a product, such as a pair of shoes, for the car fuel we buy, or for an entire multi-national company. The water footprint can also give us an idea how much water is being used by a particular country or globally.
“The water footprint is a measure of humanity’s appropriation of fresh water in volumes of water consumed and/or polluted.”
By the year 2030, experts predict that global demand for water will surpass supply by 40 percent. Impacts from climate change have already led to changes to the water cycle, leading to prolonged periods of drought (and, conversely, more extreme rainfall) in some areas. Reduced water supplies could add to water insecurity in all countries.
The water footprint shine a light on a broad range of questions for companies, governments and individuals:
where is the water dependence in the company’s operations or supply chain?
how well are regulations protecting water resources?
is it possible to do something to reduce water footprint and help to manage water for both people and nature?
Depending on the question, the water footprint can be measured in cubic metres per tonne of production, per hectare of cropland, per unit of currency and in other functional units. The water footprint give everyone a solid frame of reference that helps to understand for what purposes our limited freshwater resources are being consumed and polluted and the world be more efficient and sustainable with water use. It depends on where the water is taken from and when. If it comes from a place where water is already scarce, the consequences can be significant and require action.
Direct and indirect water use
The water footprint looks at both direct and indirect water use of a process, product, company or sector and includes water consumption and pollution throughout the full production cycle from the supply chain to the end-user.
The water footprint has three components: green, blue and grey. Together, these components provide a comprehensive picture of water use by delineating the source of water consumed, either as rainfall/soil moisture or surface/groundwater, and the volume of fresh water required for assimilation of pollutants.
The three elements of the water footprint: blue, green, and gray
Blue water footprint element is the amount of surface water resources and groundwater that is evaporated or used directly in the production chain of a particular product. In terms of consumption, it refers to the volume of water used and then evaporated or incorporated into a product; from either surface or groundwater, that is not returned to the reservoir from which it is drawn.
Green water footprint element is water from precipitation that is stored in the root zone of the soil and evaporated, transpired or incorporated by plants. One example is rainwater, provided that it does not stagnate in the soil and is able to filter into the ground.
Grey water footprint element is defined as the amount of fresh water required to dilute the pollutant load generated in manufacturing by a given process, to maintain unchanged the concentrations naturally present in its original source and to meet specific water quality, as determined by state and local standards.
The relation between consumption and water use
“The interest in the water footprint is rooted in the recognition that human impacts on freshwater systems can ultimately be linked to human consumption, and that issues like water shortages and pollution can be better understood and addressed by considering production and supply chains as a whole,” says Professor Arjen Y. Hoekstra, creator of the water footprint concept.
“Water problems are often closely tied to the structure of the global economy. Many countries have significantly externalised their water footprint, importing water-intensive goods from elsewhere. This puts pressure on the water resources in the exporting regions, where too often mechanisms for wise water governance and conservation are lacking. Not only governments, but also consumers, businesses and civil society communities can play a role in achieving a better management of water resources.”
Some facts and figures
The production of one kilogramme of beef requires approximately 15 thousand litres of water (94% green, 3% blue, 3% grey water footprint). There is a huge variation around this global average. The precise footprint of a piece of beef depends on factors such as the type of production system and the composition and origin of the feed of the cow.
The water footprint of a 150-gramme soy burger produced in the Netherlands is about 160 litres. A beef burger from the same country costs on average about 1000 litres.
The global water footprint of humanity in the period 1996-2005 was 9087 billions of cubic meters per year (74% green, 11% blue, 15% grey). Agricultural production contributes 92% to this total footprint.
Water scarcity affects over 2.7 billion people for at least one month each year.