Until recently, we have believed that water was a renewable resource, but the reality is that it is not as renewable as we thought, since it is not unlimited. Broadly speaking, we can differentiate salt water and fresh water, the second being the most important for human beings since we need it to drink, for agriculture, industry and satisfy other needs.
Water as a renewable resource
To begin with, a renewable or inexhaustible resource is defined as anything that comes from nature and that is generated faster than it is consumed. Thanks to the water cycle we have water for your use and enjoyment.
Water originates in two ways, one inside the Earth and the other on the surface. The internal route consists of a series of chemical reactions that occur inside the earth’s crust and that produce water, rising to the surface through eruptions, hot springs or geysers. On the other hand, the external route begins with the evaporation of water from the seas, reservoirs, rivers and other water sources. Animals and plants also contribute water vapor to the atmosphere through sweating and perspiration. This vapor rises to the atmosphere and when it is cooled by low temperatures it condenses and forms clouds.. The clouds move towards the interior of the continent and they are cooling favoring their precipitation in the form of water, snow or ice depending on the atmospheric temperature. Once it falls, part of the water infiltrates the ground giving rise to the existence of underground water, another part runs through the surface through rivers until it reaches the sea again and another part is used by living beings.
The uses of water
Man, as a living being, needs and uses a large part of the water for his activities. The most important uses we make of water are exemplified below .
- Domestic and urban use: a large part of the water is used for consumption and personal and household hygiene. In cities, water is used in fountains, to irrigate gardens and clean the streets, among others.
- Industry: water is used to produce products, such as in the food or cosmetic industry, as a coolant or diluent for effluents in other production processes.
- Agriculture: in some cases the water that comes naturally is used, but irrigation systems are normally used that increase and ensure the existence of crops.
- Energy: water is also used as a source of energy. We distinguish between hydroelectric energy, which uses the water currents generated when the gates in the reservoirs are opened and the water passes, the tidal energy that uses the movement of the currents produced by tidal movements and the wave energy , which results from taking advantage of the kinetic energy that waves have.
- Aquaculture: much of the fish and shellfish we consume comes from fish farms, so water is also needed as a culture medium.
- Recreational use: other human uses of water are related to leisure and sports such as swimming pools, tourism, fishing, etc.
Why water is a rare and renewable natural resource
Now that we have seen that water is considered a renewable natural resource but that it is really scarce, let’s clarify that we can in fact consider water as a limited resource .
There are several reasons why water is, and increasingly, a limited resource. It is true that the Earth is covered in 70% of water, however, fresh water, essential for our survival, only represents 2.8% of the planet’s water. Fresh water reserves on the planet are limited . 77% of fresh water is in the form of ice and snow. 21.3% is the fresh water that is in the subsoil. 0.69% is the fresh water in lakes, rivers, swamps and other reservoirs. And 0.1% is the fresh water in plants and animals. This means that only about 22% of fresh water is available for direct consumption.
However, this percentage is not entirely real since not all fresh water is drinkable and, therefore, cannot be consumed directly. In order for the water to be drunk, it must be made drinkable, that is, it must undergo a process of elimination of pathogenic microorganisms and minerals. Nor should it be forgotten that a lot of waste is dumped into water, polluting it and therefore making it unsuitable for consumption and use.
To all this we must add that not all parts of the world receive the same amount of water and also the more the population grows, the more valuable it becomes. One third of the world’s population lives in areas where water is frequently scarce and one in six inhabitants does not have access to safe drinking water. Unfortunately, the people who suffer the most from water scarcity and pollution are those who live in poor countries where there are hardly any means to treat water and waste.
Another factor that limits water as a renewable resource is the excessive use that is made of it, especially in countries with more development and comfort. It is estimated that 8% of water is consumed in homes, 22% is used for industry and energy production and 70% is used in agriculture, of which half evaporates or runs through the ground and the rest is absorbed by plants and soil.
For example, in our homes we can spend half a liter of water just to brush our teeth, between 30 and 60 liters in the dishwasher, between 70 and 120 liters in putting the washing machine and taking a bath is equivalent to spending 150 liters of drinking water. That is why it is important to turn off the tap when we are not using the water, shower instead of bathing or put the washing machines and dishwashers when they are full. In factories, about 250 liters of water are needed to make 1 kg of paper and about 300 for 1 kg of steel. And, on the other hand, in the field it would take about 2.5 liters of water to grow a lettuce, 74 liters to grow a corn plant and 38 liters to water a cherry tree.
The excessive use of water and the uneven distribution of rainfall make water a scarce commodity . If we continue to extract water at high speed and dump waste carelessly, water will soon become a non-renewable resource and it will become the new oil: an expensive and hard-to-get resource. Water is life and we should become more aware of how we use it and how we distribute it.