The water footprint: how to safeguard the most precious resource
With the help of robots, scientists are trying to find traces of water on Mars and the same thing could happen in the near future on the moons of Jupiter and Saturn. In short, water is essential for life as we know it.
On Planet Earth water is abundant but not unlimited. The total quantity of water on the Earth’s surface, in the atmosphere and below ground, is practically the same as it was at the time of the dinosaurs, but fresh water makes up just 2.5% of the total and much of it is trapped in the form of ice in the Antarctic.
The water actually available to us to meet the needs of 7 billion people makes up just 0.007% of what is present on the planet: it is therefore a precious and fragile resource that must be protected and used responsibly. That is why it is so important to talk about the water footprint.
What is the water footprint and what areas does it concern?
The term “water footprint” was coined in 2002 by the Dutch academic Arjen Hoekstra, along the lines of the other parameters: the environmental and carbon footprints. These are all indicators that measure the individual and collective impact on the environment: from the more general environmental footprint to the more specific water and carbon footprints, which, respectively, measure water consumption and carbon dioxide emissions
In actual fact this concept was not new. In 1993 British geographer John Anthony Allan had come up with the concept of “virtual water” to refer to the “hidden” or non-visible water used to produce food products and other commodities.
Building on Allan’s theory, Hoekstra formulated the concept of the water footprint to include both direct consumption, i.e., water consumed by a person, company or country, and indirect consumption that includes the sum of the water footprint of all products consumed.
Technically, the water footprint can be divided into three components:
- green water derived from atmospheric precipitation, including the water that remains for some time on the ground.
- blue water originating from surface water like lakes, rivers and underground springs.
- gray water concerns the pollution of water, and more precisely corresponds to the quantity of freshwater necessary to assimilate the polluting substances that result from human activities.
In 2008 Hoekstra founded the Water Footprint Network, an international platform that brought together companies, associations and individual citizens in order to raise awareness among the population about the water footprint and to help optimize consumption around the world.
Today the issue has become much more pressing due to a number of factors: the rapid growth of global population with the consequent increase in water consumption, climate change, which has caused an increase in anomalies such as droughts, and pollution, which reduces the quantity of clean water available to us.
Overall, the water footprint, just like its carbon equivalent, is a good indicator with which to evaluate the sustainability of production processes in our society but also our own personal behaviors. In order to assess environmental sustainability, we need to be able to measure it.
People’s water footprint
A person’s water footprint is composed only in a small part of the water consumed directly for drinking, cooking and washing. Most of it originates from the water used in the production, transport and distribution of the products we buy and consume, from food to clothes, mobility to energy consumption, products for the home to personal hygiene items.
The Water Footprint Network has estimated that the water footprint of an individual in our globalized economy can vary between 1,500 and 10,000 liters a day. This figure may seem surprisingly high at first glance and it is precisely for this reason that it should be kept in mind so we can be fully aware of our impact on the environment.
Naturally, a person’s water footprint depends on a number of different variables, including where that individual lives and their lifestyle, including their diet. In particular, consumption of red meat has a notably high impact: a 200-gram beef steak, for example, requires four times as much water as the same quantity of chicken, an amount of water equal to 47 eight-minute showers. These figures are based on the sum of water used in all phases: from the cultivation of the feed necessary to rear the livestock to the transport of the meat product to the consumer’s table.
With this in mind, the Water Footprint Network has developed an online calculator with which it is possible for anyone to work out their own water footprint based on parameters such as country of residence and meat consumption. The tool gives approximate results based on averages for people with the same characteristics. For more personalized results, it’s possible to use another online calculator, which is more precise and considers direct water consumption and dietary habits in greater detail.
In all of these calculations, however, country of residence is a key parameter. For example, a person with an annual income of 20,000 dollars and a moderate consumption uses 1,750.9 cubic meters each year if he or she lives in Austria, 2,992.2 in Mexico and 3,139.9 in Saudi Arabia, while this figure falls to 114.4 cubic meters in Burundi.
The water footprint of companies
For companies the water footprint is a more complex parameter: it measures all of the water used to produce the set of goods or services that it supplies, plus the water used along the entire supply chain and that linked to the actual use of the products.
The food industry makes particularly heavy use of water, both in terms of crops and livestock. The Water Footprint Network provides a list with the figures relating to the water footprint for various types of food, specifying the water footprint in terms of green, blue and gray water for each one. Naturally, these are approximate figures. The water footprint particularly depends on place of production and other parameters.
|Type of food||Water footprint (liters per kg)||Green (%)||Blue (%)||Gray (%)|
|Eggs||196 (for one 60 gram egg)||79||7||13|
|Pizza (margherita)||1,259 (for one pizza)||76||14||10|
|Wine||109 (for a 125 ml glass)||70||16||14|
|Beer||74 (for a 250 ml glass)||85||6||9|
|Milk||255 (for a 250 ml glass)||85||8||7|
|Coffee||132 (for a 125 ml glass)||96||1||3|
N.B. the numbers have been rounded up
The textile and clothing industry is also characterized by high water consumption, if we calculate all phases of production. For example, for a pair of jeans, water is required in order to grow the cotton, process the material and then to construct the trousers, all the way through to the final packaging of the product.
According to the Water Footprint Network a 250-gram cotton T-shirt requires the use of 2,495 liters of water (54% green, 33% blue, 13% gray), while the water footprint for leather is far higher: 17,093 liters of water per kilo (93% green, 4% blue, 3% gray).
National water footprints
As outlined earlier, the same people and products can have a different water footprint depending on their geographical location. Therefore, a country’s water footprint doesn’t only depend on its population or Gross Domestic Product, but on numerous factors that make it difficult to calculate. Nevertheless, the Water Footprint Network has also developed a tool for doing just this.
The countries with the largest water footprints are China and India, each with an annual water consumption of more than 1,000 billion cubic meters. In third place is the United States with just over 900 billion cubic meters a year: this figure is very similar to those of the Asian giants yet the US population numbers less than a quarter of those of India and China.
The fourth most populous country, Indonesia, is preceded in this special ranking by Russia and Brazil and followed by Nigeria, Argentina, Canada and Pakistan. The figure for Argentina stands out because the country has a population of just 40 million and yet it ranks higher than demographic giants like Pakistan and Mexico and also economic powerhouses like Japan and Germany.
Italy, with 62 billion cubic meters a year, sits outside the top twenty in all categories.
As one might expect, the parts of Italy with a large water footprint are the main metropolitan areas and, above all, the Po Valley, the largest in demographic and economic terms. At the opposite end are the mountain areas, in particular those in the Apennines and inland Sicily and Sardinia.
How to reduce water consumption
Awareness of the issue of water footprints has grown notably in recent years, above all in the business sphere. An increasing number of companies are paying attention to their own water consumption and are endeavoring to reduce it. This reflects the growing attention towards environmental sustainability and the circular economy model. Indeed, reusing water is arguably the most natural action regarding circularity.
In order to reduce its water footprint the Enel Group began back in 2018 with the Matching project, studying solutions to reduce water consumption at electricity generation plants. More recently, the WaVe (Water Value Enhancement) project includes various initiatives to promote water-saving measures and a more efficient use of this resource.
While hydroelectric energy is the most directly concerned with the management of water, all power generation plants can benefit from an optimization of their water footprint. In Chile, for example, a system has been implemented to recover water from evaporation towers and other industrial processes at the San Isidro plant. In the Balearic Islands, on the other hand, specifically at the Mahón factory, wastewater from the nearby municipal treatment plants is being used to power a nitrogen oxide abatement system. At the Santa Barbara plant in Tuscany, the adoption of new specifically formulated reagents and the use of an advanced control system have enabled a 15% reduction in the plant’s water requirements.
As far as solar energy is concerned, a new innovative technique using natural humidity to clean photovoltaic panels has been introduced at our plants in the extremely arid Atacama desert in Chile. In Panama, on the other hand, the mechanized washing of panels has replaced manual washing, thereby reducing the use of water. These are just some examples that give an overview of the Enel Group’s numerous initiatives to optimize water management.
Nor is it just a question of small and large companies: individual citizens can also make a contribution by reducing their water footprint through their day-to-day behavior. Even the simplest changes can make a difference, like turning off the tap when applying soap or brushing teeth, and generally avoiding wasting water, as well as, obviously, taking care not to pollute rivers, lakes and seas.
But you can also reduce your water footprint by making more aware consumer choices based on the data outlined above or with online calculators. Reducing consumption of red meat, for example, or cutting down on unnecessary clothing purchases and maybe avoiding items with a large water footprint, rewarding companies that are careful with their water consumption both by publicizing their own water footprint and above all, implementing tangible initiatives to reduce it.
Individuals alone, however, cannot change the world and grassroots initiatives are not enough: what’s needed is a widespread change of mentality supported by governments and companies. Indeed, safeguarding water is a duty for everyone, because water, like the air, belongs to us all: water is life.