The Nature is a system in biological balance of all the beings livings creature. In this system in balance, the organisms thus produce substances that are useful for other and successively.
The pollution always appears that trashes (solid, liquid or gaseous), produced for microorganisms or the man, will be in upper amount to the capacity of absortion of the environment, provoking alteration in it and compromising the survival of the species.
The aquatic ecosystem is extremely susceptible to suffer to pollution and contaminations derived from the activities human beings, as agriculture, industry an uncontrolled urbanization and badly planned.
The pollution directly is related to the enormous amount of efluents originated in the production of good, the irrigation of farmings, application of agrotoxics, in the domestic activities, emission of sewers in the sources, etc.
The pollution is a aggression to the Nature, to man environment - its effect are factor of concern of innumerable organizations of environment defense, that search ways to hinder its action.
This if must the two factors:
1- All pollutant soluble in water launch in air and ground, it has as final destination the underground rivers, lakes, oceans and subterraneam sheet.
2- The human beings (as well as the other beings livingd creature) need the water to survive. About 70% the mass of human body it is of water, it is main the half one of substance carrier in the inward of the organism, for example, the blood nothing more is of that on water mixture and foods the must all be distributed to the cells of the body. Moreover, it is the water that regulates the temperature of the environment and the temperature internal of the man, birds and animals - so that this remains constant. Daily, each human being ingests of two the four liters of water, pure or incorporated to foods; of these, it eliminates of two the three liters, in perspiration and excretion. The amount of available water to be used to advantage Land readily is small e badly distributed geographically.
Our survival will depend on the quality of this water; as well as we cannot waste it, we must guarantee its potalibity. The water is considered potable when it does not possess harmful elements to the health human being. These elements can be of chemical nature (toxic substances) or biological (pathogenic organisms).