Introduction

• Water is everywhere, and it is very important to the Earth and the life inhabiting it, including us.
• Our Earth seems to be unique among the other known celestial bodies.
• It has water, which covers three-fourths of its surface and constitutes 60-70 wt % of the living world.

97% oceans, 3% fresh water

• Only 1% of the water available is used by the organisms on Earth.

2.997% ice caps and glaciers, 0.003% ground water

• About 97% is salty sea water, and 2% is frozen in glaciers and polar ice caps.
•  As the water available for use is very less it is a necessary commodity for life.