Every product we consume, every food we eat and every garment we wear needs water to exist. What is surprising is that most of that water is never seen by us: it is used in production, transport or cultivation processes.
Understanding what the water footprint is and how to calculate it helps us make more conscious decisions and reduce the environmental impact we generate without realising it.
What is the water footprint?
The water footprint is an indicator that measures the total amount of fresh water used to produce goods or services. It not only includes the water we use directly, such as the water that comes out of the tap or the water we use to water plants, but also all the water needed indirectly: the water used to grow food, manufacture products or generate energy.
For example, when you drink a cup of coffee, there is much more behind it than just the 200 millilitres of water it contains: there is water used in the cultivation, processing, transport and preparation of the coffee. In total, that cup can represent around 140 litres of water.
This concept was developed in the early 2000s by Professor Arjen Hoekstra of the University of Twente as a way of making visible the hidden water consumption behind the global economy. Since then, it has become an essential tool for measuring and managing environmental impact both at a personal and business level.
Types of water footprint
The water footprint is divided into three main types: green, blue and grey. Each one represents a different type of water use within the life cycle of a product.
Green
The green water footprint corresponds to rainwater that is used and evaporates during the growth of plants. For example, wheat, maize or coffee absorb water from the soil thanks to rainfall. That amount is considered part of their green water footprint.
It is the most sustainable of the three, as it does not involve extracting water from rivers or aquifers. However, it is still limited: it depends on climate conditions and the efficient use of land.
Blue
The blue water footprint refers to fresh water extracted from rivers, lakes or aquifers for irrigation, industrial processes or household consumption. This type of water is the one that comes under the most pressure in contexts of drought or overexploitation.
For example, growing cotton in arid regions consumes large amounts of blue water for irrigation, which can deplete local water resources and affect entire ecosystems.
Grey
The grey water footprint measures the amount of water needed to dilute the pollutants generated during a process until they reach safe levels for the environment. In other words, it represents the impact of water pollution.
An example: if a paper factory releases chemical waste into a river, the grey water footprint calculates how much water would be needed so that those pollutants do not exceed the limits established by environmental regulations.
Water footprint calculation
Calculating the water footprint may seem complex, but the central idea is simple: add up the green, blue and grey water consumption of a product, process or person over a given period.
At an individual level, there are online calculators that allow us to estimate our personal water footprint by taking into account habits such as how much meat we eat each week, the type of clothes we buy, how much time we spend in the shower or how often we wash the car. You can also use the WFN website.
At a business or industrial level, the calculation is more technical. The methodology of the Water Footprint Network is used, which analyses water use at each stage of the value chain. The result is expressed in litres or cubic metres of water per unit of product. Here is the page, and it really is useful for calculating your own consumption as well.
Example: how much water is needed to produce one kilo of meat
Of all the foods we consume, meat, especially beef, is one of the products with the highest water footprint. Producing just one kilo of beef can require between 13,000 and 15,000 litres of water, depending on the production system and the animals’ feed. This enormous consumption comes from several sources:
- Green water, used to grow the grass and cereals that serve as feed.
- Blue water, used for irrigating crops and supplying the animals directly.
- Grey water, needed to dilute the waste generated in breeding, transport and processing.
By comparison, producing one kilo of lentils requires around 1,250 litres of water, almost ten times less. That is why reducing meat consumption or choosing meat from sustainable systems can drastically reduce our personal water footprint.
How does the water footprint affect the environment?
When the use of water resources exceeds the natural capacity for replenishment, serious ecological imbalances are created, such as:
- Fresh water scarcity: excessive extraction from rivers and aquifers can cause droughts and leave local communities without supply.
- Loss of biodiversity: aquatic ecosystems such as rivers, lakes and wetlands depend on water balance. If it is altered, entire species can disappear.
- Pollution of soils and groundwater: polluted grey water affects drinking water quality and the health of ecosystems.
- Social and economic conflicts: in many regions, competition for water between agriculture, industry and human consumption creates growing tensions.
- In addition, climate change worsens the problem, reducing water availability in many areas and increasing the frequency of extreme droughts.
That is why measuring and managing the water footprint is a priority in the sustainability policies of companies and governments, and all of us must do our part.
How you can reduce your water footprint
To reduce your water footprint, you do not need to stop using water, but to use less of it and in a smarter way. Small everyday actions can make a big difference if we adopt them consistently. Here are some recommendations that all of us can follow:
- Moderate your meat consumption. You do not have to stop eating it, but replacing part of your diet with plant proteins such as pulses, tofu and nuts can reduce your water footprint by up to 30%.
- Buy clothes consciously. Every cotton garment needs thousands of litres of water. Choosing recycled materials or reusing clothes extends the product life cycle and saves resources.
- Do not waste food. When you throw food away, you are also throwing away the water used to produce it. Plan your shopping and freeze what you are not going to consume.
- Install efficient systems. Reducing shower time, using taps with aerators or low consumption washing machines significantly lowers household water use.
- Choose local and seasonal products. Foods transported from far away involve more processes and therefore a greater total water footprint.
- Support sustainable companies. More and more brands are being transparent about their water footprint and are working to reduce it. Supporting those companies drives real change in the market.
The water footprint invites us to look at water from a new perspective: not only as a resource that comes out of the tap, but as a vital element that supports everything we consume. Calculating it and understanding it allows us to act responsibly, reduce waste and choose products that respect the limits of the planet.
