Theory:

Water is one of the most important substances for the survival of living organisms. One can survive without food, but it is impossible to survive without water. The temperature of our planet is regulated by water. Water also  helps to maintain the temperature in organisms.
 
Sources and forms of water
There are different water sources including, rainwater, seawater, well, ponds, river, and lake.
Water is found in three forms. They are as follows:
  1. Solid form
  2. Liquid form
  3. Gaseous or vapour form
The water that circulates in the water cycle can be found in all the three forms.
 
1.  Solid form:
Water is found in the solid form as snow on the mountains and ice as in the ice caps at the poles of the earth. The mountains that are covered by snow are known as glaciers.
 
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2.  Liquid form:
Water is found in liquid form in the oceans, rivers, lakes and in the underground.
 
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3.  Gaseous form:
Water vapour is the gaseous form of water. It is found in the atmosphere.