Our earth is rightly called the blue planet because of its abundant store of surface water. However, only 2.5 percent of it is freshwater, with most of it locked up as snow and permafrost, leaving only 0.3 percent of that in liquid form. And with the heavy agricultural and industrial use of fresh water, and the resulting pollution, very little of it is left for our drinking water needs.
To satiate the thirst of the burgeoning human population, we need to tap into our vast oceans and seas. Even coastal countries and island populations are reeling under severe scarcity of potable water. It is a case of “water, water, everywhere, but not a drop to drink.” The high salt content of sea water is the main deterrent here.
The salinity of marine water averages around 3.5 percent. It is like 35 grams of salt dissolved in a one liter bottle of water! Drinking such salty water defeats the very purpose of drinking water, as it neither satiates your thirst, nor hydrates your body. In fact, it will cause severe dehydration and death.
While there are many filtration and disinfection techniques such as sand and charcoal filtration, chlorination, and ultra-violet radiation to make contaminated fresh water into clean drinking water, it is not possible to remove the salt from the water through the above measures. But the salt must be removed.