Water reuse evaluation
Introduction
Water resources are called all the water available or potentially available, in sufficient quantity and quality, in a given place and in a given period of time, appropriate to satisfy an identifiable demand.[1] Frequently, this term is used in relation to easily accessible fresh water, regardless of the physical state in which it is found, liquid or solid, that can be used by humans to satisfy some need, such as the supply of drinking water to the population, irrigation or energy production. In a more general sense, the concept of water resources refers to any type of productive water or directly linked to a use or exploitation, so in this case, a water resource would be any body of water existing on the planet from the oceans to rivers, including lakes, streams and lagoons. Sometimes we speak of water resource or hydraulic resource in the same sense.[2].
In recent years, humanity has become aware of the imperative need to preserve ''water resources''', avoiding waste and, above all, avoiding their contamination. We are still very far from achieving a rational use of these natural resources that, although they are, in part, renewable, there is a danger that the increase in their use and pollution will exceed their self-regenerative capacity. WATER is essential for human survival and well-being, and is important to many sectors of the economy. Water resources are distributed unevenly in space and time, and are under pressure due to human activities. [3].
As is already known, two thirds of the Earth's surface is submerged and the majority, around 97% of the total, is contained in the seas and oceans, that is, it is salt water whose use requires additional activities such as desalination. The rest, around 3% of the planet's water is fresh water; However, it is not easily accessible, since most of it is found in polar caps or glaciers and only a small part of the total, around 0.5%, is found in rivers and lakes;[4] that is, it is surface fresh water available for direct use as a water resource, although it must be said that said water is not distributed homogeneously, since the quantity and disposition of water resources varies enormously depending on the region. geographical. The distribution of fresh water available for human consumption is highly variable from region to region. At the most critical extreme, in some parts of the Middle East, availability is around 136 liters per inhabitant per day. At the other extreme, in humid and sparsely populated areas the availability exceeds 274 m³ per inhabitant per day. [5]Finally, while in some places water resources are wasted, in others it is a particularly scarce commodity. In addition, there are different polluting agents and activities that threaten the preservation of water, and that require constant measures to keep them at bay.