Not only the water that we see in front of us when we use it is all that we consume. Most of the water we consume is found in the products and services we use every day. The actions we take to take care of it, through the indirect use we have of it, will have a great impact on our savings.
The water footprint (HH) is an indicator of all the water we use in our daily life; to produce our food, in industrial processes and energy generation, as well as that which we dirty and pollute through those same processes.
This indicator allows us to know the amount that a person, a consumer group, a region, country or all of humanity uses.
The HH considers the place where the water comes from and, based on this, classifies it into 3 types or colors: blue, green and gray:
It refers to that found in surface water bodies (rivers, lakes, estuaries, etc.) and underground; that is to say, the surface and underground extraction of a certain basin.
That is, if after being used it returns intact to the same place from which it was taken within a short time, it is not taken into account as HH.
It is the rainwater stored in the soil as moisture. Particularly the use of rainwater used during the evapotranspiration of the soil that is used in agriculture and forestry production.
It is all the water contaminated during a process. However, this is not an indicator of the amount of contaminated water, but rather of the amount of fresh water necessary to assimilate the load of contaminants, given the known natural concentrations of these and the local water quality standards in force.
The sum of the green, blue and gray water that a product or service requires within the entire production process will be its water footprint.
A cotton shirt
The water content of a cotton shirt, results from adding the water used for plant growth and that derived from the industrial processing of cotton seed, from which the fabric is obtained.
To obtain 1 kilo of cotton cloth, 10,800 liters of water are required. Of that amount, 45% represents the irrigation water consumed by the cotton plant; 41% is rainwater that evaporates from the crop field during the growing season; and 14% is the water necessary to dilute the residual water resulting from the use of fertilizers in the field and of chemical substances in the textile industry: approximately 30 thousand liters of water per ton of cotton are required for bleaching the fabric and for fabric dyeing 140 thousand liters per ton. Thus, a cotton shirt, weighing approximately 250 grams, has a water footprint of 2,700 liters.
Denim pants are made from combed or carded cotton, which is derived from cotton fiber, which comes from cotton seeds. Before the final cotton textile reaches the hands of a consumer, it goes through a series of processes and intermediate products. The average water footprint of the printed cotton of a pair of jeans weighing 1 kilogram is 11,000 liters.
To obtain 1kg of refined sugar from sugar cane, around 1,500 liters of water are required. Sugarcane consumes around 220 billion cubic meters of water per year, equivalent to 3.4% of world water consumption for agricultural production. Sugar beet sugar requires less water per kg.
The water footprint of pure chocolate is 2,400 liters for a 100 gram bar (world average). Composition of dark chocolate: 40% cocoa paste (HH of 33,260 liters / kg); 20% cocoa butter (HH of 50,730 liters / kg) 40% sugar (HH 1,526 liters / kg). So we can calculate 40% of 33,260 + 20% of 50,730 + 40% of 1526 = 24,060 liters / kg = 2,400 liters for a 100 gr chocolate bar. The water footprint of powdered milk is slightly higher than dark chocolate when the total cocoa content is the same (around 2,500 liters for a 100 gr chocolate bar). Most crucial to the HH of chocolate is the paste and cocoa butter content.
It costs about 21,000 liters of water to produce 1 kg of roasted coffee. For a normal cup of coffee, 7 grams of roasted coffee are required, so a cup of coffee costs 140 liters of water. Assuming that a normal cup of coffee is 125 ml, then we need more than 1,100 drops of water to produce one drop of coffee. Drinking tea instead of coffee would save a great deal of water. 30 liters of water are required for a standard 250 ml cup of tea.
The HH of a cow (for meat production) is 3,100,000 liters. In an industrial meat production system, it takes an average of three years before the animal is slaughtered to produce about 200 kg of boneless meat.
The animal consumes about 1,300 kg of grains (wheat, oats, barley, corn, dry peas, soybean meal and other small grains), 7,200 kg of forages (pastures, dry hay, silage and others), 24 m³ of water for drink and 7 m³ of water for maintenance. This means that to produce one kilogram of boneless beef, we use about 6.5 kg of grain, 36 kg of fodder and 155 liters of water (only for consumption and maintenance. The production of the grains necessary for food alone requires 15,300 liters of water on average.
The global average water footprint of whole cow's milk is 940 liters per kg. About 28% of this amount goes to butter derived from whole milk and the remaining 72% to skim milk. One kilogram of whole milk gives about 50 grams of butter, so the water footprint of butter is 5,550 liters per kg.
The global average water footprint of whole cow's milk is 940 liters per kg. About 50% of this amount goes to fresh unfermented cheese that is derived from whole milk and the remaining 50% from whey. One kilogram of whole milk gives about 95 grams of cheese, so the water footprint of cheese is 5,060 liters / kg.
Here are other examples:
- 1 potato (100 g): 25 liters
- 1 apple (100 g): 70 liters
- 1 tomato (70 g): 13 liters
- 1 orange (100 g): 50 liters
- 1 slice of bread (30 g): 40 liters
- 1 slice of bread (30 g) with cheese (10 g): 90 liters
- 1 egg (40 g): 135 liters
- 1 bag of potato chips (200 g): 185 liters
- 1 hamburger (150 g): 2,400 liters
- 1 glass of beer (250 ml): 75 liters
- 1 glass of milk (200 ml): 200 liters
- 1 cup of tea (250 ml): 35 liters
- 1 glass of wine (125 ml): 120 liters
- 1 glass of apple juice (200 ml): 190 liters
- 1 glass of orange juice (200 ml): 170 liters
- 1 pair of shoes (bovine skin): 8 thousand liters
- 1 sheet of A4 paper (80 g / m2): 10 liters
- 1 microchip (2 g): 32 liters
If you want to know the Water Footprint of other products, here is a site that has an important list, although it is in English, it has graphics and images of each food.
Source: Agua Viertual and Huella Hídrica