Every day should be World Water Day, simply because we are water. So much so that approximately 70% of our body is made up of this liquid. Thales of Miletus, a Greek philosopher and mathematician who lived between 624 and 546 BC, stated that water is the beginning of all things. Its supremacy over the rest of the elements has been known since ancient times. In fact, the development of the great civilizations took place in the vicinity of important watercourses, as was the case of Mesopotamia around the Tigris and Euphrates, Egypt on the Nile or the Xian and Shian dynasties around the Yellow River. In Europe, large cities have also been organized around a river: Paris and the Seine, Rome and the Tiber or London and the Thames.

Water is currently the source of strong social conflicts and, especially in areas where it is scarce, there is a close link between power over water and power over the people. In addition to scarcity, in recent decades we have been witnessing a new water crisis: water pollution.

In underdeveloped or developing countries development, wastewater is not adequately treated. Thus, in Latin America, slightly more than 80% of polluted water is deposited in natural watercourses without any treatment. In developed countries, on the other hand, there is sufficient technology and energy capacity to treat it adequately. It is in the Wastewater Treatment Plants (known by the acronym WWTP) where the wastewater is carried out management in order to reduce the impact of contaminated water on the natural environment. This management involves high energy consumption, the generation of which, in turn, has a negative impact on the environment.

On the other hand, the quality of treated water is generally lower than the quality of the initial water. The higher the purification Degree the higher the economic investment required, so it is necessary to find a balance. Once the treated water is returned to the watercourse, nature performs the final purification step.

The energy expense is derived from the operation of conventional WWTPs whose operation to decontaminate the water involves high electricity consumption. General wastewater treatment includes: filtering and decanting to remove suspended solids; separation of grease and sand; treatment with microorganisms to remove biodegradable organic subject and final disinfection. Therefore, aerators, water impulsion pumps and scrapers in constant movement are some of the equipment used and which involve electricity consumption in the treatment plant.

At this point, the following questions can be raised: Is the water problem really an energy problem? If an inexhaustible energy source were to be obtained that would make it possible to treat wastewater indefinitely, would the problem of water pollution be eradicated?

Today, the generation of wastewater has a negative impact, both due to the loss of quality and to the generation of the energy needed to treat the water. In this sense, it is necessary and fundamental to moderate its use in order not to produce excess wastewater; to carry out an adequate treatment of the contaminated water to reduce the environmental impact once it is deposited in the riverbed; and to trust in the assimilation capacity of nature in order to continue enjoying springs full of quality water, that is to say, full of life.