The Rainwater Opportunity
Mumbai, a city renowned for its spectacular monsoon downpours, often sees millions of litres of this precious resource flow away into drainage systems
annually. This is a stark contrast to the situation in other Indian cities, such as Bengaluru, which face severe water scarcity. Witnessing this potential being wasted, a resident from Malad, Subhajit Mukherjee, conceptualized and developed a remarkably economical approach to harvesting rainwater and simultaneously replenishing groundwater reserves. His ingenuity was sparked by an idea previously shared by retired IPS officer Kiran Bedi, and he collaborated with engineers from IIT-Bombay to bring his vision to life. The result is a practical, budget-friendly system that utilizes readily available materials like PVC pipes and a water barrel.
Simple Barrel System
Mukherjee's ingenious design centers around a readily accessible water barrel or drum. The fundamental steps involve preparing the drum by drilling numerous holes across its entire surface. Simultaneously, a pit, ideally measuring 3x3 ft or 5x5 ft, needs to be excavated. Once the pit is ready, the prepared drum is carefully positioned within it. To facilitate the collection of rainwater from your terrace, a PVC pipe is then connected, channeling the water directly into the drum. The surrounding pit is then filled with layers of pebbles and stones. This crucial step serves a dual purpose: it helps prevent soil and debris from entering the drum, thus maintaining water purity, and it also provides stability, ensuring the drum remains securely in place. This collected rainwater then percolates underground, contributing significantly to the replenishment of groundwater tables, as well as supporting nearby water bodies like ponds, lakes, and tube wells.
Beyond Recharge
In addition to its groundwater recharge capabilities, Subhajit Mukherjee's innovative system can be adapted to store water for non-drinking purposes. This variation of the setup allows for the collection and retention of rainwater for periods extending up to 10 days, offering a valuable resource for everyday household needs that don't require potable water. The overall cost for implementing this effective rainwater harvesting and groundwater recharge system typically ranges between Rs 2,500 and Rs 5,000. This economical solution has already demonstrated its significant impact, helping schools, parks, and housing societies across Mumbai conserve thousands of litres of water, turning a wasted resource into a valuable asset.
