Industrial areas take to rainwater harvesting in Bangalore

Marianne de Nazareth

Ground water table has been over exploited and harvesting the rain is the only way forward. The industries realise this and have begun to implement

Fresh water sources are drying up in Bangalore as our requirements outstrip our availability. Going along with Michael Baptiste and Vijayraj of Farmland Rainwater Harvesting System to the Sarjapur Industrial Area, the positive steps which are being taken by big companies regarding rain water harvesting was an eye opener. Sarjapur, housing many office complexes and industries is reeling under a lack of fresh water sources as the bore wells have dried up. Obviously this means the ground water table has been over exploited and so harvesting the rain is the only way forward which the industries realise and have begun to implement.

My first stop was at Smith Kline and French (SKF) factory premises in Sarjapur. It was an eye-opener to see that every single one of the factory buildings are now connected by a series of collection pipes. These pipes collect all the rain water which falls on the roof and channelises it towards massive storage tanks after being filtered through the water filter.

Innovative filters

The innovative, dual density filters are unlike the conventional filters. The dual intensity filter works on the principal of cohesive and centrifugal force. I saw them in action and realise that the open ended design works on gravitational force with no external energy required. There is an automatic flush-out of particles of debris that might come in off the roof in the water. Other filters have a gate valve on the side and the only way the debris can be cleaned by manually opening the valve and periodically cleaning it, explains Vijayraj while showing me the working of the filter. With decay of the debris there is a definite chance of contamination of water and if the debris is not cleaned there could be an overflow of water

We walked around SKF and noticed that every single roof has been connected by pipes and after filtration, the water was collected in massive sumps, to be used in the premises. Infact even the water that fell in the rest of the property, was channelised towards an area where it could percolate into the ground.

In the Indian IT MNC, Infosys property, that is where we got to see the injection wells. Here the rain water was channelised into a silt trap, as the water came from across the property and contained everything from leaves to sand. Once the water overflows in the silt trap, it then flows into the well, which has a wire filter, and the water passes through multi layers of filtration.

Considering an average rainfall spread of 70 days per year, the approximate quantum of water percolating through this injection well is 2.1 million litres per injection well