This week marks another important environmental event, World Water Day. This date on the calendar serves as a reminder that water is the most important substance for life, essential for the health and economic well-being of humankind.

The use and distribution of this indispensable resource almost always involves ethical considerations, and the problems caused by its unavailability underlie some of the most serious conflicts between peoples and communities.

In fact, droughts cause more deaths from famine and more economic losses than any other natural disaster. About two-thirds of the world's population now lives in areas that experience water shortages for at least one month a year.

Moreover, control of water implies not only control of economic well-being, but also control of life itself. In recent decades, several international conferences have invoked ethical principles, such as the need to guarantee basic water needs for all human beings. Among these conferences was the Earth Summit held in Rio de Janeiro in 1992.

Estimates of people without easy access to safe drinking water represent 25% of the world's population, and about half of the world's population does not have an adequate sanitation system to dispose of their excreta and household waste. These two factors combined give rise to the main causes of mortality and morbidity in these countries.

An integrated water policy must take into account the negative effects of pollution on the quality of life and the environment, and include measures for the treatment of urban and industrial discharges.

In this regard, in a recent conference given at the Royal Casino of Santa Cruz de Tenerife, I presented a reflection on the use of water as another product of the Circular Economy. In it I explained that wastewater, once treated, can be treated in appropriate regeneration plants and reused (for agricultural or recreational use, irrigation of golf courses, parks and gardens, etc.) if guaranteed quality controls are applied.

This management of water as a product of the circular economy is based on its responsible use through the well-known "three Rs": reduce, recycle and reuse. Firstly, in the different uses of water - domestic, urban, agricultural, urban, industrial, recreational, etc. - it is necessary to reduce consumption through more advanced technologies, as well as to avoid water losses in supply and distribution networks as much as possible. Secondly, it is urgent to have the necessary infrastructure - purification and reclamation plants - to recycle urban and industrial effluent water and reuse it, already reclaimed, for certain uses. The underlying idea is that the linear flow of water (resource - water/product - wastewater) should be transformed into a circular flow (resource - water/product - wastewater - recycled resource or reclaimed water).

The reuse of treated water is essential in the natural water cycle. For this reason, the European Union's Water Framework Directive (2000/60/EEC) proposes its reuse as a measure to solve the problems of water scarcity. This "second life" of the water resource is a common practice, especially in arid and semi-arid regions, in the interests of environmental sustainability.

In addition, current purification technologies make it possible to obtain regenerated effluent water (liquid coming from an industrial plant) of various qualities. It can thus be used for various purposes (agricultural, industrial, recreational, municipal, etc.). Managing water reuse requires advanced tertiary treatments. It also requires weighing the economic cost against the benefits. However, it is imperative that we understand this resource within the parameters of the Circular Economy, otherwise the perverse effects of not having access to quality water will be greatly aggravated.