What is a water footprint?

Water is key to the proper functioning of many of Earth’s systems. However, as the water footprint of modern day business practices has grown exponentially, so has the pressure on the hydrological cycle. Water usage is found in all value chains: whether it’s a primary input (e.g. in agriculture), in the process stage (e.g. mineral extraction) or in the water and sanitation facilities provided for workers. There is no value chain on Earth that does not use water and therefore a water footprint.

Despite water’s critical role in value chains, the amount and type of water used is often not immediately obvious to either others in the supply chain or the end user.

This is an issue, as without a comprehensive understanding of the water within a product or service, it is difficult to reduce our impact on water resources.

Below we talk about the concepts and tools all businesses that have water inputs can use to start to understand the ‘water footprint’ of their products.

What is ‘virtual water’?

Virtual water is the water used throughout the value chain of a product or service. It is usually invisible to the end-user and the concept was developed by Tony Allen.

What is a Water Footprint?

It is a calculation of how much ‘virtual’ water is used to create a product. A water footprint provides powerful insights for businesses into their water-related business risk. The concept was developed by Arjen Hoekstra.

How is a Water Footprint calculated?

The water footprint is calculated through a Water Footprint Assessment which includes:

• quantifying and mapping the water inputs into a product.
• assessing the sustainability, efficiency and equitability of water use

The three types of water included within a Water Footprint Assessment are:

• Green water: This is rainwater, soil moisture & evaporation used either directly or evaporated.

• Blue water: This is surface water and/or groundwater used either directly or evaporated. This is the water type used for irrigation. Whilst surface water (e.g. rivers and lakes) can be over-abstracted, they are less vulnerable to over-abstraction than groundwater (e.g. aquifers). Aquifers can take hundreds to thousands of years to replenish.
• ‍Grey water: this is the freshwater (green or blue) used to dilute the polluting outputs of a value chain. To protect local water quality, in many countries  there are regulations on how diluted a pollutant needs to be. However, this polluted ‘greywater’ is often toxic in large quantities and pollutes water systems.

An important note on context

Geographical context is very important within a Water Footprint Assessment, as the distribution of green and blue water varies across geographies. As such the water footprint for products like fresh produce, varies hugely depending on the location, whether irrigation was used.

For more information on Water Footprint Assessments we recommend checking out the Water Footprint Network website. Here you can find Business Resources on Water Footprinting, more about the Global Water Footprint Standard.

Want to find out more about water footprinting and how it may help your business? Please contact us at hello@bemari.co.uk to arrange an introduction call.