Prospects of Using Rainwater as a Local Resource

With severe water shortage facing Indian cities and their inability to treat the sewage generated the need to optimize water use in residential areas has become an imperative. With 50% world population living in cities, and India's rapid urbanization in consonance, the security of water supply for domestic use is uncertain. Improving efficiency of city supply, modification of personal habits, use of efficient plumbing fixtures in buildings, use of treated greywater and capture and use of rainwater locally are some strategies which are being explored in response to this crisis. Amongst all these tapping rainwater has a multitude of benefits. Firstly, it can be collected and used locally if storage strategies are worked out. Being a distillate it is pure and the impurities present in rainwater are gathered on its journey to the earth's surface and thereafter to the tank. At this point in time, its quality characteristics make it suitable for bathing, washing clothes, flushing toilets, gardening, etc. If sufficient water is collected the demand for city supply of potable water could reduce dramatically. If rainwater were contained locally by directing to storage or groundwater recharge, the menace of urban flooding would be largely mitigated. Recharging will ensure improved water tables, improved quality of ground water and an assured supply for the future. However, despite the rosy picture this source is left largely un-exploited and this paper examines some of the key characteristics of Indian rainfall and their implications for using harvested rainwater as regular supplementary source of water.