Water covers three-fourth of the Earth’s surface, with over 97% present in the oceans and less than 1% in freshwater streams. Water is also present in the atmosphere in solid form in the polar icecaps and as groundwater in aquifers (water-bearing rocks) deep underground.
Water has many remarkable properties. It is sometimes referred to as ‘the universal solvent’, readily dissolving a wide range of chemical substances. It also acts as a fluid medium facilitating the dispersal of un-dissolved particulate matter.