Water is very essential for life. It is one of the most abundant resources of the earth, covering about 3/4th of earth’s surface.
Though it covers earth’s major portion yet there is severe shortage of potable water in many countries around the world mainly developing countries and Middle East region countries.
The reason for this situation is that nearly 97.5% of earth’s water is salt water present in oceans and remaining 2.5% is fresh water which is in the form of ground water, ice-mountains, lakes and rivers, which serves most human and animal needs
According to UNEP (United Nations Environment Program) 1/3rd of the world’s population lives in countries with insufficient freshwater resources
Hence enormous efforts are required to make new water resources available and minimize water deficiency in countries with shortage of fresh water
World Health Organization guidelines state that the permissible limits of salinity in drinking water are 500 ppm and in few cases it may extend up to 1000 ppm.
Most of the water on earth has salinity ranging up to 10,000 ppm and for sea water it may be in the range of 35,000 – 45,000 ppm due to its dissolved salts
For every 20 years, the consumption rate of water is doubling exceeding by two times the rate of population growth.
The potable water resources are on the decline and water demand is high.
In recent times various industrial and developmental activities have resulted in increasing pollution and deteriorating the quality of water.
Thus water shortages and unreliable quality of water are considered to be major hindrances for sustainable development of society.
The existing water resources are decreasing
Due to unbalanced distribution of rain water and drought
Extreme exploitation of ground water resources and
its un sufficient recharge
Degradation of water quality due to the discharge of domestic and industrial wastes without sufficient treatment
Since the fresh water resources are very limited to serve the major population needs and salt water is unsuitable for many applications, desalination of salt water (sea water) emerges as a boon to most of the population to serve their needs