Did you know that the production of any cotton T-shirt you buy requires 2,700 liters of water for its production? This is because cotton farming is the largest consumer of water within the supply chain of the fashion world. But how is it possible to calculate these data and know these results? Thanks to the water footprint indicator. The concept of “water footprint” was included in 2002 as a different indicator and as an alternative of greater complexity than the concept of “water use”. Since then, organizations such as UNESCO and the Water Footprint Network have studied various examples of water footprint with the aim of promoting efficient, fair and sustainable use of water. latest advances in knowledge, information and ideas to combat water scarcity.
What is the water footprint – simple definition
The water footprint is the term used to indicate the direct or indirect use that human beings make of fresh water on the planet. It is an indicator widely used in environmental and sustainability studies to measure the total volume of fresh water that is used in the production of goods and services of a company, or simply, the volume of water consumed directly by an individual or a community.
To do this, the water footprint indicator calculates the use of water through the volume of water that has been consumed, evaporated or even contaminated (taking into account whether the calculation is made per unit of time for the index of individuals and communities, or per unit of mass in the case of companies).
Types of water footprint
Within the different types of water footprint we can differentiate between:
- Water footprint of direct water consumption: it is the one that calculates the water used and / or contaminated during the entire manufacturing process of a product, as well as the water that is incorporated into the product itself as an ingredient.
- Water footprint of indirect water consumption: refers to all the water that is needed to produce the different raw materials used in any production and supply process.
On the other hand, the water footprint is expressed on numerous occasions as colors, so that, depending on the type of water considered, we find:
- Green water footprint: refers to the volume of water that is evaporated from the planet’s water resources and the rainwater that is stored in the soil as moisture.
- Blue water footprint: that related to the volume of fresh water consumed from the water resources of surface and groundwater on the planet.
- Gray water footprint: studies the quality of water and its possible contamination due to discharges of waste and toxic substances, as well as the volume of contaminated water associated with the production of goods and services, taking into account the amount of water that will be needed add to the volume of already contaminated water, in order to dilute said contamination.
Furthermore, this important indicator can be applied both to the group of consumers (individuals, towns, cities, or even nations), as well as to the main producers (public bodies and companies) around the world.
As an example of a water footprint that refers both to the use of water by consumers, as well as by producers, the calculation of the water footprint of food stands out .
In addition, it has become one of the most important water footprints worldwide, due to the alarming amounts of water that are calculated to be necessary for the production of food that we consume in our day to day, such as:
- 13,000 liters of water are needed to produce 1 kg of beef.
- 3,920 liters of water = 1 kg of chicken.
- 3,000 liters of water = 1 kg of rice.
In the next section of this article we will see in detail how the water footprint is calculated to obtain data on the volumes of water that are used in the different food production processes and other goods and services.
For the quantification of the water footprint , the method may vary depending on the type of assessment (individual consumer, consumer communities, or conversely, small and large-scale producers). Generally, the steps to calculate the water footprint are as follows:
- Collection of data on the different types of use and sources of water as a natural resource, including the reports associated with the water footprints named with the colors green, blue and gray.
- Water balance per unit (volume and concentration of water inlets and outlets within the process). Subsequently, if necessary, it will be included in the global balance in which several processes are included.
- Analysis of the sustainability of the water footprint.
- Response to the water footprint, including projects and strategies aimed at reducing it.