I am Rajiv Hemanth. I have been a Water Sustainability consultant with Biome Environmental Solutions, working on Design and Implementation of Rainwater Harvesting, Grey Water Recycling systems and Black water management systems for the last 5 years. My work has been centered mostly around Bangalore India, though the occasional project has taken me to other states/ cities in India as well. In addition to the above, I have also been involved in mapping the ground water aquifer in a 34 square kilometer area in Bangalore, providing Water and Sanitation literacy to school kids in rural Bangalore, enabling international volunteers/ students to work with rural schools.
Bangalore has seen a dramatic spurt in population over the last decade or so and this has had a direct impact on its water resources.
Illustration: Bangalore Population decadal growth rate
Though the old city was pretty self-sufficient with surface water supply from a river 100 kilometers away and 0.5 kilometer below (Bangalore is at an elevation of approximately 1000 metres above mean sea level), the new peripheral parts of Bangalore do not yet have connected water supply and thereby rely heavily on ground water. This has led to an alarming drop in levels of ground water which has forced people to buy water at a high price from unorganized private water suppliers. Slowly, rainwater harvesting started gaining ground as a much better sustainable alternative.
Rainwater Harvesting systems here focus on storage and reuse of rooftop runoff and recharge of ground water with the surface runoff. I shall get into the details of the what’s and how’s in my subsequent posts.
Illustration: A Rainwater Harvesting System in a house in Bangalore
I find it interesting to compare the Rainwater Harvesting systems here in India with those in the Unites States. For instance, Rainwater Harvesting regulation seems pretty diverse for the different states in the Unites States and in certain states like Colorado, Rainwater Harvesting was made legal through a recent regulation and there is a cap of 110 gallons that an individual household can harvest in their property. In Texas, there is a subsidy on the purchase of Rainwater Harvesting equipment. In India, again rainwater harvesting regulations pretty much vary by states. The Karnataka state government of which Bangalore is a part of requires that every household residing in a plot which is more than 120 square meters in area should install a rainwater harvesting system with guidelines on the minimum quantum that needs to be harvested. Also, any new house construction happening in any size of plot (even the ones which are less than 120 square metres) should have a system installed.
The underlying technique of Rainwater Harvesting will be the same irrespective of where it is done – identifying the catchment area, providing appropriate conveyance mechanisms to transfer the water from the catchment to storage, appropriate filtration mechanisms depending on intended end use of water and finally storage of the collected water in a storage system. The differences would be in the details which should be quite interesting to explore and research.