What Makes a Blue, Green or Grey 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).

Being sustainable means using blue water wisely and not making grey water. Humans have polluted much water. Some rivers have so much rubbish in place that boats are pushing their way through the rubbish, for example, the Lake Karachay in Russia. It was the dumping site for radioactive waste, the water under the rubbish has chemicals from factories and toilets. Here we look at the 3 different definitions of water footprint categories and how each is used when determining a water footprint.

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.