Capturing rain a matter of life and death for growing Indian cities
"With the population literally bursting out of the cities seams and water getting scarcer, the need of the hour is to employ rain water harvesting on a war footing," states Jeff D'Lemos, who is a rain water harvesting specialist and provided this reporter with a firsthand view of the projects he has established to trap rain water in order to recharge the depleted ground water table.
We visited the house of Dr. B Raghu where D'Lemos had set up pipes to harvest the rain off Dr Raghu's roof and channel it to his sump and also to recharge his dry bore-well. There is no water from the Cauvery river available in this neighborhood so the residents depend on bore-well water.
With the onset of the "software boom," what was meant to be a residential development with bungalows like Dr. Raghu's has become a concrete jungle of flats. "Mine was the only house in an open area of plots three years ago," said Dr. Raghu. Today he is almost choked with flats coming up on every similar plot.
"Each apartment block has 30 flats so we can look at an average of 120 people living in one building. Calculate, if one person uses 100 liters of water per day into 365 days, what is the quantum of water needed?" says D'Lemos. "No wonder all the bore wells are going dry. Once they they dry out completely how do people live? They have already hit over 900 feet to get water here."
"The geology of Bangalore's soil is clay on top, soft rock lower, medium rock below that and granite at the bottom," explains D'Lemos. "Therefore one cannot just dig shallow holes where the rain collects and expect that to replenish the water table, the clay soil prevents that."
He explained that there are three options to harvest rain water. The rainwater can be collected and sent to fill an underground sump, or the water can be directed to recharge the bore-well if the roof area is less than 100 sq meters. The third option is for the water to be channeled into an open well.
In a nearby apartment block, a water tanker is unloading water for the residents who need to buy two tankers each day to survive. Santosh Hebbar one of the residents reveals that they pay INR32,000 (USD70) per month for water. Now with D'Lemos setting up the rain water harvesting system in just a few days they need to buy tanker water has been halved. In a matter of a few months the entire investment in the system will be recovered.
In the Da'Costa neighborhood the residents have got together and installed a rain water harvesting system which, according to spokesman Brian Papali: "Has been wonderful. We fill tanks with the rainwater which is used to wash our cars, water the garden and wash the common areas of the building. The excess is channeled to recharge the borewell rather than let it flow on the road or into the sewage system."
D'Lemos and Papali are committed to water conservation, along with many other Bangalore residents who have suffered water shortages in the burgeoning city. "I want to start a movement here in Bangalore, a self help movement, to educate people to help themselves.
It has also helped that the local government has made it mandatory to harvest rain water in new buildings in some areas and since Bangalore experiences plentiful rain it is considered a priority to capture the rain to recharge the water table that which has been depleting for over 40 years.