What is a Water Footprint?
Your water footprint G is the amount of water you use in and around your home, school or office throughout the day. It includes the water you use directly (e.g., from a tap). It also includes the water it took to produce the food you eat, the products you buy, the energy you consume and even the water you save when you recycle. You may not drink, feel or see this virtual water, G but it actually makes up the majority of your water footprint.
Why Do Water Footprints Matter?
Freshwater is vital to life, and as the world's population grows, so does our use of it. Globally, the increase is due in part to more people drinking and bathing, but as developing countries like China and India grow more prosperous, more people are consuming more water-intensive food, electricity and consumer goods. This puts pressure on water resources, which is a concern in the arid parts of the US and the rest of the world where food is grown, goods are manufactured and water is already in short supply.
By the year 2030, experts predict that global demand for water will outstrip supply by 40 percent. Impacts from climate change may increase the likelihood of changes to the water cycle, leading to prolonged periods of drought (and, conversely, more extreme rainfall). Reduced water supplies could add to water insecurity both in the US and in other countries.
Water footprints help individuals, businesses and countries because they reveal water use patterns, from the individual level all the way to the national level. They shine a light on the water used in all the processes involved in manufacturing and producing our goods and services. A water footprint also accounts for the amount of water contaminated during manufacturing and production because that water is made unusable and is, essentially, taken out of the system.
The water footprint gives everyone - from individuals to business managers to public officials - a solid frame of reference that helps us all be more efficient and sustainable with our water use and appreciate the role of water in our lives.
What Makes a Blue, Green or Grey Water Footprint?
A water footprint is measured in terms of the volume of water consumed, evaporated and polluted. The Water Footprint Network, whose research provides data that drive our calculator, splits water footprints into three corresponding categories:
Blue Water Footprint : The amount of surface water and groundwater required (evaporated or used directly) to make a product.
Green Water Footprint : The amount of rainwater required (evaporated or used directly) to make a product.
Grey Water Footprint : The amount of freshwater required to mix and dilute pollutants enough to maintain water quality according to certain standards (like the ones established in the US Clean Water Act) as a result of making a product.
Examples of how each of these contributes to an item's total water footprint can be found in the Water Footprint Network's Product Gallery.
The Water Footprint Concept
The water footprint concept, sources and methodology come from the Water Footprint Network (WFN). The concept was created by Dr. Arjen Hoekstra who, along with the others at the WFN, developed the framework and established the international organization as the foremost research network in the discipline.