The water footprint concept was introduced in 2002 by Professor Arjen Hoekstra, as a metric to measure the amount of water consumed and polluted to produce goods and services along an entire supply chain. It is a multidimensional indicator, showing water consumption volumes by source, and polluted volumes by type of pollution; all components of a total water footprint are specified geographically and temporally.
In February 2011, our non-profit partner, Water Footprint Network, launched the Global Water Footprint Standard, a collaborative effort of environmental organisations, companies, research institutions and the United Nations. The standard was published in The water footprint assessment manual: Setting the global standard.
The water footprint measures the amount of water used to produce each of the goods and services we use. It can be measured for a single process (such as growing rice), for a product (such as a pair of jeans), for the fuel we put in our car, or for an entire multi-national company. The water footprint can also tell us how much water is being consumed globally, or by a particular country in a specific river basin or aquifer.
To calculate a water footprint and understand its meaning, companies or organisations need to conduct a Water Footprint Assessment, as described in The Water Footprint Assessment Manual.
Method
A Water Footprint Assessment is a four-phase process that quantifies and maps green, blue, and grey water footprints, assesses the sustainability, efficiency, and equitability of water use, and identifies which strategic actions should be prioritised to make a footprint sustainable.
Water Footprint Assessment is versatile and can inform a broad range of strategic actions and policies from environmental, social, and economic perspectives.
There are four phases of a Water Footprint Assessment:
A Water Footprint Assessment begins with setting the goals and scope of the water footprint study. Water Footprint Assessment can be undertaken for diverse purposes.
For example, it can be undertaken to:
A Water Footprint Assessment can be tailored to meet the goals and scope of the study. The goal of the Water Footprint Assessment clarifies what you will do in the subsequent steps: accounting, sustainability assessment and response formulation. The scope of the assessment defines the spatial and temporal scale of the study, for example whether the focus will be global or within a single catchment, whether it will span one year or multiple years, whether it will include some or all of the value chain, address one product or a facility or an entire company.
Together, the goal and scope indicate which data will be used, how each subsequent step of the assessment will be approached and the level of detail required to achieve the desired results.
Once the goal and scope of the Water Footprint Assessment have been defined, the data are collected to calculate the footprint of the relevant processes for the study.
These may come from global databases, such as WaterStat, or collected locally. The calculations for the green, blue and grey water footprint follow the methodology described in the Water Footprint Assessment Manual.
Water Footprint Assessment is used to assess whether water use is environmentally sustainable, resource efficient and equitably allocated.
In the sustainability assessment step, we are assessing whether water use is balancing the needs of people and nature, if our limited water resources are being used to the greatest benefit and how fairly we are sharing the waters we use.
Using the information gained in the accounting and sustainability assessment steps of Water Footprint Assessment, response strategies that reduce the water footprint and improve its sustainability can be prioritised for implementation.