The importance of rainwater harvesting lies in the fact that it can be stored for future use. Just as it can be used directly so also the stored water can be utilized to revitalize the ground level water and improve its quality. This also helps to raise the level of ground water which then can be easily accessible. The harvesting of rainwater simply involves the collection of water from surfaces on which rain falls, and subsequently storing this water for later use. Normally water is collected from the roofs of buildings and stored in rainwater tanks. It will reduce water bills, provide an alternative supply during water restrictions and help maintain a green, healthy garden. In fact, depending upon tank size and climate, rainwater harvesting can reduce mains water use by 100%.