The rational use of water is about the control and management of its consumption. It is a concept included in the management policy of renewable natural resources and associated with sustainable development that must allow the use of resources. In the case of water, its quality must be guaranteed by avoiding its degradation, in order not to compromise or put at risk its future availability. These principles are applied in engineering, architecture, urban planning and agricultural projects that are conceived within the framework of the protection, care and conservation of natural resources.

Water is essential for all humanity, as well as for all living beings that inhabit planet Earth. We not only depend on it to live, but it is essential for the development of food as well as for sustainable economic development. It is made especially relevant by the fact that without water it is completely impossible for life to occur, and it is also the first thing that is taken into account when searching for life outside our planet. On Earth, where water is a real good, its proper and sustainable use allows economic development; on the contrary, difficult access to drinking water causes diseases and decimates populations.

However, a large portion of this water is salty, as a consequence of the salinization process suffered when infiltrating between the minerals of the Earth's crust. In general terms, of the 1.4 billion km³ of water in the world, only 33 million are fresh water. From this amount we would have to deduct 87.3% that is in the form of ice in the polar caps and glaciers, and 12.3% that constitutes groundwater. There is only 0.4% of usable water left, in volume 140,000 km³. This quantity, in turn, is in an incessant movement of evaporation - runoff, in the phenomenon called the hydrological cycle or water cycle. Therefore, the amount of water that can actually be used is very small, and is also subject to numerous sources of pollution, so it must be used rationally.

On the other hand there are the sewage networks. The fact that sewage or simply waste water circulates in the same place where people do poses a high risk to their health, increasing the level of diseases and hindering the development of the affected population.

Investment in infrastructure, whether sewage to channel waste water, or facilitating access to drinking water for the entire population of the planet, are aspects that must be influenced so that water becomes a right and stops being a privilege.