What is the water footprint?

The water footprint is an essential tool to understand the impacts human have on this essential yet finite resource.

Water has become increasingly vulnerable as a result of climate change, population growth and growing pressure on this resource. In this context of global scarcity, there is an urgent need to calculate the water footprint as it is a tool that enables us to understand where, when and how water is used. This information is essential to utilize freshwater in countries, companies, processes and products in a more sustainable and fairer way

The water footprint is divided into three main types:

  • Green water footprint: the volume of rainwater consumed. In other words, water from precipitation that is stored in plant roots and absorbed, evaporated and transpired by crops.
  • Blue water footprint: the volume of surface and groundwater required for the production of goods and services.
  • Gray water footprint: the amount of water needed to dilute pollutants in water to achieve acceptable water quality standards.  

Differences between the concept of the “water footprint requirements of ISO 14046” and “Water Footprint from the Water Footprint Network (WFN)”

The concept “water footprint” was coined by Professor Arjen Hoekstra, University of Twente (The Netherlands) in 2002. It is a global environmental indicator that measures the total volume of freshwater used to produce goods and services, whether for individual consumption, community consumption, or business production. Subsequently, initiatives such as the Water Footprint Network (WFN) have developed this idea, which focuses on assessing the direct and indirect use of water.

The “water footprint” according to ISO 14046 is based on the Life Cycle Assessment (LCA) methodology, establishing the principles, requirements and guidelines required to correctly assess the water footprint of products, processes and organizations, based on the analysis of their life cycle. This new concept does not only account for the volume of water consumed, but also evaluates the possible environmental impacts of this consumption.

 water footprint

The origins and objectives of the two methodologies are different. Although both pursue the conservation of water resources, they do so in different ways. The main difference between the WFN water footprint and the ISO 14046 water footprint is that the WFN methodology offers a volumetric approach while ISO 14046 offers an environmental impact approach.

Calculation phases of both methodologies:

  1. Study objectives and scope: this defines the purpose and extent of the analysis.
  2. Water footprint accounting: this quantifies water use in all its dimensions.
  3. Impact: this assesses the consequences of water consumption for the environment and society.
  4. Interpretation of results: this provides an in-depth understanding of the situation, facilitating informed decision-making.

The calculation of the water footprint varies depending on who consumes the water:

  1. A company’s water footprint: this covers the water used in the production and supply chain, as well as during product use. This comprehensive calculation, often made by experts, is essential to understand and improve sustainable water management. Companies participating in initiatives such as the EsAgua Network receive support to reach sustainability goals in water use, with benefits ranging from efficient water management to improved reputation and market positioning.
  2. Product water footprint: this measures the amount of water consumed and polluted at all stages of a product’s manufacture. Water footprints can be calculated through methodologies such as the Water Footprint Network manual. There are also interactive tools, such as the Water Footprint Network’s Product Gallery, which enable consumers to compare the impact of different products and make informed decisions to reduce their water footprint in their daily consumption.
  3. Personal water footprint: this represents the water needed to produce the goods and services consumed by an individual. Tools such as the one developed by UNESCO-IHE can assess the individual water footprint based on water needs per unit of product and country of residence.
  4. National water footprint: this assesses the total amount of water used to produce the goods and services consumed by a country’s inhabitants.

In conclusion, the water footprint provides a detailed understanding of the water impact of products, companies and nations, enabling informed decision-making to conserve this vital resource. By measuring not only the quantity, but also the quality and geographic distribution of water used, it is a comprehensive tool to encourage more responsible practices and contribute to the long-term conservation of our water resources.

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