Earlier work has suggested that with the increase in the consumption of water due to the growing population of Delhi, there is a continuous decrease in the water level in the parts of Delhi. Due to this decline water is getting saline which is making it harmful for vegetation; also its taste is being affected. To overcome such problems rainwater harvesting systems have been established. Rainwater harvesting dilutes the dissolved salts in ground water. In the present study water samples, from various societies of Dwarka subcity of New Delhi have been collected where rainwater harvesting systems are installed. The impact of rainwater harvesting on the quality of ground water has been studied by collecting water samples from these selected sites in the months before after and during the rain. The present study revealed that the rainwater harvesting suitably affected the quality of ground water.