When we talk about climate change, we hear terms like carbon footprint and zero emissions. But have you heard of the term “water footprint?”
The concept of water footprint arises from the fact that fresh water is consumed during many activities that we do not necessarily associate with water, such as the production of goods and services.
Water footprint definition
Water footprint is an indicator of environmental health that refers to the volume (in liters or cubic meters) of fresh water that is used in the production of a consumer item or service throughout the entire manufacturing cycle.
The numbers are mind-boggling:
- It takes 1000 liters of water to produce a liter of milk.
- A mug of coffee requires 850 liters of water!
- Globally, 2 billion people live in countries that are experiencing high water stress.
We must remember that fresh water is a finite resource. Only 3% of the world’s water is freshwater. Due to global warming, polluted runoff, and excessive development, the amount of freshwater available is shrinking.
The situation reminds me of these famous lines from the Rime of the Ancient Mariner by Samuel Taylor Coleridge:
“Water, water every where. Nor any drop to drink.”
Water footprint can be calculated for an individual, a process, a business, the production cycle of a product, or even an entire country.
The goal is to be mindful of the amount of water consumed by various processes and thus develop sustainable water use practices.
Types of water footprint
There are three types of water footprint depending on the source of freshwater:
a) Blue water footprint – volume of water evaporated from groundwater reservoirs or surface water bodies to produce goods and services.
b) Green water footprint – volume of water evaporated from rainwater (that remains in soil as moisture) to produce goods and services
c) Gray water footprint – volume of polluted water required to produce goods and services (calculated as the amount of freshwater needed to dilute pollutants to make the water quality acceptable)
The term “water footprint” was coined by Arjen Hoekstra in 2002. He founded the Water Footprint Network in 2008 along with other notable people.
Water footprint calculation
The United Nations has noted that global water use is growing twice as fast as population growth. If this unsustainable rate continues, two-thirds of the world’s population will face water stress by 2025.
The water footprint of a country is calculated from two perspectives: production and consumption.
Production involves the volume of freshwater used from local water resources in the manufacture of goods and services. It includes the water footprint of agriculture, domestic use, and industrial use. Production can also be measured for an administrative unit such as a city, province, or river basin.
Consumption involves water used in the production of goods and services that are consumed by the people of the country. This aspect of water footprint could be partly internal and partly external as some goods and services may be imported and not locally produced.
The water footprint of production and consumption together describe the pattern of water consumption of a country and provide insights into how to manage water use.