Water is a very stable chemical compound, made up of hydrogen and oxygen atoms, with the formula H2O. Water is odorless, tasteless and colorless, and its enormous presence on Earth (71% of it is covered with water) largely determines the existence of life on our planet. Water is the only substance that exists at ordinary temperatures in all three states of matter. It exists in a solid state as ice, found in glaciers and polar caps, and in the form of snow, hail, and frost. As a liquid, it is found in rain clouds formed by drops of water, in the form of dew in vegetation, and in oceans, seas, lakes, rivers, etc. Like gas, or water vapor, exists in the form of fog, vapor and clouds.
Although the water in the seas and oceans appears to be blue or blue-green in color, the water is colorless. The observed color is the result of diffusion, absorption, and especially reflection / refraction of light that penetrates the marine and oceanic surface. The water of the oceans and seas constitutes 97% of the water present on Earth, and it is salty because, in addition to being made up of hydrogen and oxygen, it contains dissolved solid matters such as NaCl, potassium, magnesium and calcium. The remaining 3% is water from rivers, lakes, lagoons, groundwater, permanent ice and glaciers, which is generally sweet and is used in almost all activities carried out by human groups.
The absence of water has always been associated with the disappearance of living beings, that is why it is said that water is essential for human life. It is the main thermoregulatory agent of the body, it allows to achieve a balance of temperatures throughout the body. Our body, and any other living being, needs water to function normally, since both the biochemical reactions and the proper transport of substances take place in aqueous solution. Furthermore, water makes up at least two-thirds of the human body.
Human societies use the available water for irrigation of fields and crops, for cleaning and preparing food, for personal hygiene, industry uses it as a refrigerant and solvent for many substances, etc.; There are also other uses that do not involve consumption. For example, obtaining electricity from hydroelectric plants, recreational use of the seas, lakes, reservoirs and rivers, and navigation. Water used for human consumption must be drinkable. This is drinkable when it has dissolved a certain portion of air and some salts and also lacks substances harmful to health.
Today, water pollution is a serious problem for humanity, so we must all avoid it and conserve this resource so essential for the existence of life on Earth.
