Can we quench humanity's thirst with virtual water?
By 2025 an estimated 1.8 billion people will be living in countries or regions with absolute water scarcity. Absolute water scarcity refers to a physical lack of water meaning that there are no natural water sources available in the region. To address issues of water scarcity we control water resources with engineering; traditionally with the construction of dams. These projects have allowed for cheaper food outputs, and safer water and sanitation supplies for many people, and yet water scarcity challenges persist in many communities. One emerging solution for water scarce regions is to import virtual water.
Virtual water is defined as the amount of water used to produce a product or service. The term “virtual” is used since the amount of water contained in the product can be negligible compared to the amount used in the production. It is relatively easy to calculate our direct water consumption - water used for drinking, and domestic use - but what about calculating virtual water use? We do this by calculating a product’s water footprint.
Similar to the no doubt familiar concept of the carbon footprint, a water footprint is an indication of the water used by consumers or producers either indirectly or directly. Scientists and policy makers can use the water footprint to help assess humanity’s impact on the planet. You too can assess your impact by determining the virtual water content contained in some everyday items. For example, some average virtual water values for commonly consumed items are 140 litres for one cup of coffee, 2000 for one cotton T-shirt, and 2400 for one hamburger. Through assessing products virtual water content and national consumption patterns a country’s water footprint can be calculated.
A country’s water footprint is closely linked to its gross national income as well as its meat consumption. To sustain Canada’s national population, 2.05 million litres of water per person/year are required, much higher than the global average of 1.24. In addition to being a large consumer of virtual water, Canada adds to its water footprint by exporting agricultural products. Agriculture is a very water intensive process consuming 70% of Canada’s fresh water withdrawn each year; therefore, countries facing water scarcities look to import agricultural products. Due to its high volume of agricultural exports, Canada is a major virtual water exporter, second in the world only to the United States.
However, despite a large water footprint, Canada is usually described as a country with an inexhaustible fresh water supply but we still intermittently suffer from fresh water shortages, even in areas where water supply has traditionally been abundant. Regardless of the actual availability of water, it is still imperative to manage this valuable natural resource wisely because water withdrawal for domestic, food and industrial use has a major impact on ecosystems. Curious about how your patterns of consumption relate to virtual water use? Check out www.waterfootprint.org to learn more about water footprint calculations for specific products and discover your own water footprint. The results may make your throat dry.
Hoekstra, A. & Chapagain, A. (2007). Water Footprints of Nations: Water Use by People as a Function of their Consumption Pattern. Water Resource Management 21, pp. 35-48.
Percy, D. (2005). Responding to Water Scarcity in Western Canada. Texas Law Review 83(209), pp. 2091-2107.
United Nations Water. (2013). Water Resources: Statistics, Graphs and Maps [online]. Available at: http://www.unwater.org/statistics_res.html [Accessed 2013-03-23]