The English expression “on tap” means something that is readily available any time. Described in chemistry as a “colourless, odourless” liquid, water used to be on tap – not any longer, though. Pure drinking water has become a precious commodity. We have already got used to buying it at no small price. We are living in an ever thirstier world!

    There is a view that if there were a World War III, it might well be about water! A water molecule (H2 O) consists of two Hydrogen (H) atoms and one Oxygen (O) atom. Water is truly the blood of the earth. It is the agent of geological, environmental and such other global changes. It is vital to life and makes up 70% of our body. It covers 70% of the earth’s surface, which is why the earth looks like a blue marble, viewed from space.

   Water in our oceans has a volume of 1300 million cubic km - enough to fill a sphere of diameter 1350 km. Though the....