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Photo: Laura D'Alessandro / CC BY-SA

The Carbon Trust's Dr John Kazer explores the importance of product water footprinting for businesses

So how much water goes into a cup of tea? Somewhere around 30 litres of water is required for tea itself, 10 litres for a small dash of milk and a further 6 litres for each teaspoon of sugar. This means that a simple cup of tea with milk and two sugars could actually require 52 litres of water – enough to fill my kettle more than 30 times.

Taking a life cycle approach involves understanding how much water is consumed in every stage of the production, use and disposal of a product. In the case of a cup of tea this includes: the water needed to grow the tea leaves and the sugar cane, as well as growing the feedstock consumed by dairy cows; the water used in the manufacturing process for both the main products and their packaging; the water used to brew the tea and clean the dirty cup; not to mention a number of other things such as the water used to generate the energy to boil the kettle.

There are over 60 billion cups of tea consumed in Britain each year. Making some general assumptions on the amount of these that have milk and sugar in them, this adds up to a footprint of around 3,000 billion litres of water. This means that each year our collective enjoyment of tea makes use of one and a half times the volume of water in the UK’s largest reservoir, Kielder Water in Northumbria.

The reason that it is important to understand the life cycle water footprint of products is because globally there is an increasing demand on water resources, which are not being adequately replenished. According to the latest figures from the UN, if we continue our on current trajectory then by 2050 water demand is projected to grow by 55 percent. This projected growth comes from a variety of areas, including the manufacturing, agriculture and energy sectors, alongside domestic use as access to sanitation improves in developing countries.

The increase in water demand is unsustainable. By 2025 it is estimated that two-thirds of the globe could be experiencing water stress, including 1.8 billion people facing absolute water scarcity. This is why businesses need to focus on understanding and reducing their water consumption. Otherwise they could find themselves at best facing higher costs for excessive use of a key resource, or at worst losing their social license to operate under competing priorities.

But just counting the total number of litres doesn’t give you the full story. Water in products is described in a variety of colours: blue water is the freshwater that comes from lakes, rivers and aquifers; green water comes from rain; greywater is reusable wastewater, of the sort that might come from sinks, showers or washing machines.

Water footprints tend to focus on blue water as the important element. This is because the sustainability issues associated with water tend to relate to freshwater, which is also more practically manageable than rainfall. 

But managing even a freshwater footprint isn’t easy. It requires consideration of local impact, on both water quality and scarcity. Using large volumes of freshwater somewhere like the north of China, a region facing serious water shortages and major issues with pollution, is a far greater issue than using it somewhere like Canada, which has 20 percent of the world’s freshwater supply.

To look at what this means in the tea example, more than 80 percent of the total water footprint for growing tea leaves is green water from rainfall, because it is typically grown in wet regions. So the actual impact on the local blue water resources is fairly minimal. The consequences are not the same as abstracting a reservoir and a half of water of freshwater every year.

When businesses understand the total amount of water consumed by their products, alongside their water impact, they can focus their efforts to make improvements and identify supply chain or regulatory risks. These risks can be substantially reduced by ensuring that water-intensive production takes place in water-abundant areas. Greater water efficiency can also result in some very compelling cost savings, particularly where energy is required to cool, heat or pump that water.

So even if life cycle assessment is not your cup of tea, there is a very good reason to water footprint your products.


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