There are one blue water footprint, one green water footprint it's a gray water footprint. But when it comes to water footprint, Water Footprint, we mean the sum of these three components and not just one.
Water footprint is the sustainability indicator that allows you to evaluate the total amount of water consumed or polluted for the creation of a product. We said that there are three footprints of this type, identified with different colors:
- Blue water footprint indicates the volume of fresh water subtracted from the natural cycle (by taking it from rivers, lakes and aquifers) for domestic, industrial purposes or for irrigation of cultivated fields.
- Green water footprint indicates the volume of rainwater transpired by plants during cultivation.
- Gray water footprint represents the volume of polluted water, quantified as the volume of water necessary to dilute the pollutants to the point that the quality of the water returns to meet the quality standards.
Speaking of food, you need 13 liters of water to ripen a tomato, 40 liters for a slice of bread, 500 liters for 100 grams of cheese and 2,400 liters for a hamburger.
Water footprint of diets
By eating in one way rather than another we can be more or less 'dewatering'. In fact, each eating style corresponds to a certain consumption of water, that is a very specific one water footprint.
Cereals, fruits and vegetables are the foods with the least impact in terms of consumption of water resources. Conversely, meat and animal derivatives are also the foods to which the greatest is associated water footprint.
In general, the consumption of water for food varies from about 1,500-2,600 liters in the case of a vegetarian diet to about 4,000-5,000 liters for a diet rich in meat. It follows that the Mediterranean diet is among the most respectful of the water resource.
But there is more: considering that frequent and regular consumption of cereals, fruits and vegetables of the Mediterranean diet is recommended, while low consumption of meat and animal derivatives, the dewatering diet (rich in animal fats and sugars) appears negative both for people's health and for the planet's water resources.
Resources of which it is good to get an idea. If it is defined as 'blue gold' it is because only 2.5% of all available water on earth is fresh water. Most (79%) of this already small share is not usable because it is enclosed in the polar caps and glaciers. 20% is made up of groundwater. Rivers, lakes, basins and wetlands therefore represent less than 1% of available fresh water.