Theory:

Conservation of water
The earth has an abundance of water. But, most of it is in the form of ocean and seawater. Only a small fraction of it in the form of groundwater is suitable for the usage of living organisms like plants, animals and humans.
With the drastic decrease in the level of groundwater, the demand for groundwater increases. Groundwater is a renewable resource with high demand as we are using it more than the amount that can be renewed.

Increase in population will spike the demand for groundwater usage for food production industries.  Hence, the conservation of groundwater is very important and essential need.
Steps that should be taken to conserve water:
  • Reduce the agricultural wastage of water by increasing the efficiency of irrigation.
  • Reduce the domestic water wastage.
  • Recycling of the used water.
  • Promote rainwater harvesting.
  • Constructing plants for the desalination of seawater, so that more water is available for usage. 
Rainwater harvesting
It is an important process through which the availability of water can be increased.
The process of collecting rainwater and storing it for future use is known as rainwater harvesting.
"Catch water where it falls" is the basic concept on which rainwater harvesting is based upon.
Preferably the following two techniques are used for rainwater harvesting:
 
1. Rooftop rainwater harvesting: In this technique, the rainwater is collected from rooftop to a storage tank via pipes. This water contains impurities like traces of soil and hence, need to be filtered before use. We can also let the pipes go directly into a pit in the ground instead of a tank. With this, the water can go into the soil and refill the groundwater.
 
2. In the second technique, the rainwater from the roadside drains is collected and sent directly into the ground.