There is a need to conserve water because of the following reasons-

a. When the ground water level decreases, the amount of water on earth remains the same but the amount that is available for use to use is very limited because fallen level of ground water means that water cannot be used. So, water should be conserved in order to increase the ground water level and also to fulfil the shortage of water when underground water level goes down drastically.

b. There is a continuous increase in the population with which the demand of water for use is also increasing. With more people and same amount of water on the planet, there will come a time when the world will have shortage of water. So, water should be conserved for a sustainable future where the coming generations do not have to face shortage of water.