Distillation is employed in purification or separation of substances from mixtures;. Water obtained by condensing the vapour is known as distilled water. Distilled water is practically free from any impurities. It is odourless and tasteless. It does not contain pathogenic bacteria also. Hence consuming distilled water is not harmful.
Our normal drinking water is obtained from either river or well. It contains lot of minerals depending upon the nature of the soil. These minerals are essential for any organism, because they are the sons of the soil, a mixture of minerals.
Mineral water from natural springs commonly has a high content of calcium carbonate, magnesium sulphate, potassium, and sodium sulphate. It may also be impregnated with such gases as carbon dioxide or hydrogen sulfide.
In the meantime, it should be noted that all the mineral water need not be biologically safe. Now-a-days mineral waters are artificially made by mixing enough minerals to distilled water. The mineral conent of both natural and artificial mineral water varies greatly.
Organisms have to maintain an internal balance between water and dissolved materials (known as osmoregulation) regardless of environmental conditions. In many marine organisms osmosis (the passage of solvent through a semi permeable membrane) occurs without any need for regulatory mechanisms because the cells have the same osmotic pressure as the sea.
Other organisms, however, must actively take on, conserve, or excrete water or salts in order to maintain their internal water-mineral content.
Published in The Hindu on Dec 6, 2001.