Explanation: Desalination of water is basically a process of purifying ocean water which is saline water to a water which can be used for drinking purpose.
Earth's surface consists of 70% of water which has only 3% of drinkable water. The desalination process on large scale involves boiling water and water vapor to a large extent which require very high energy.
The processes which are carried for desalination are: Reverse osmosis and electro-dialysis.
These processes are very costly and cannot be done on a large scale due to the economic wealth of the country.
Moreover, water is directly taken from the oceans and thus might harm marine life.
Therefore, it is not widely used.
