The water is a tasteless, odorless, colorless substance whose molecules consist of two hydrogen atoms and an oxygen atom. It is an essential element for the development of life. Something hard, on the other hand, is not soft, exerts resistance, or is rough.
Hard water is known as that which hinders the development of foam when in contact with soap, due to the fact that it has a high amount of magnesium and calcium bicarbonates and carbonates. To calculate the hardness of water, the concentrations of magnesium and calcium that are present in each liter of water are usually added together.
The opposite of hard water is soft water: the liquid that has a very low amount of mineral salts. When there is no mineral in the water (that is, when it is formed only by hydrogen and oxygen), we speak of distilled water.
In addition to magnesium and calcium, the hardness of the water is determined according to the amount of zinc, manganese or iron, among other cations (a cation is an ion whose electrical charge is positive, therefore it is deduced that it has suffered a loss electrons; their oxidation state is positive). According to the World Health Organization (WHO), this value must be expressed in milligrams of substances equivalent to carbonate per liter of water; when it does not reach 60, then we are faced with soft water.
Water hardness can be permanent or temporary. In the case of permanent hard water, no matter how much it is boiled, magnesium and calcium chlorides and sulfates are conserved since, after reaching a certain temperature, their solubility begins to decrease.
The hard water temporary, however, can lose their toughness when it is added calcium hydroxide or when boiled. This is because its carbonates can dissolve and therefore be removed.
It is important to know that hard water causes various problems. When hard water is used in clothes irons, water heaters, washing machines or boilers, it is common for carbonates to become embedded in tanks and ducts. In this way, the appliances can become clogged and stop working properly.
The hardness of water directly affects its organoleptic properties, that is, in all those parameters that we can use to describe its physical characteristics according to the perception that our senses have of them, among which are its texture, smell, taste, temperature. and color.
The WHO ensures that water with a hardness exceeding 200 mg / l carries the risk of scale formation in tanks and pipes, while if it is below 100 mg / l it can lead to long-term corrosion.
Leaving aside machines and pipes, there are experts who assure that in humans it can lead to the appearance of kidney stones, although none of the studies carried out specifically on this subject since 1984 have yielded scientific evidence that supports the risks that many attribute to hard water. The general trend, however, is to avoid its consumption in children and people with urinary problems.