What Is a Water Footprint?
You’ve probably heard the term “carbon footprint,” but have you heard of a “water footprint”? A water footprint refers to…
how much consumptive freshwater a product, person or land area uses. (Consumptive water is water that becomes temporally unavailable due to evaporation or quality decline.)
The water footprint calculation was developed by the Water Footprint Network and accounts for all the freshwater that a product, person or land area consumes. For example, the water footprint for a loaf of bread would include all the consumptive water required to produce the bread during each step in the supply chain—from the water required to grow the wheat to any water used until the bread reaches the shelf.
The water footprint also accounts for three different types of freshwater consumption—green water use, blue water use and grey water use. Green water use is consumption from rainfall, blue water use is groundwater or surface water consumption, and grey water use refers to the dilution water required to reduce pollution to acceptable levels.
Why should we know about water footprints?
Calculating water footprints is important because it allows us to see how much rainfall, surface water, and groundwater we use and where we use it. Although freshwater is renewable, its availability is still limited. For example, we can’t control when and where rainfall will occur. A water footprint recognizes this and emphasizes how humans need to use freshwater efficiently. This calculation can also be used with a measurement for water scarcity, which can help us judge the sustainability of a system.
Excerpted and adapted from:
D. Dourte and C. Fraisse, What is a Water Footprint?: An Overview and Applications in Agriculture (AE484), UF/IFAS Agricultural and Biological Engineering Department (01/2012).
“Introduction,” Water Footprint Network (Accessed 07/2015).