Looking for sustainable sources

The summer is behind us. But not the discontent over water that gave Bangaloreans sleepless nights. One still does not know if the copious rains that have visited us will keep a date with the reservoirs through which our lifeline, the river Cauvery flows. It is only cogent and farsighted planning that can ensure sufficient, if not ample, water for unquenchable thirst of an ever-expanding Bangalore.

Currently Bangalore’s water needs are fulfilled from two sources, Cauvery and groundwater. The planners should think of looking for alternative sources as well as augmenting the existing ones. Simultaneous efforts need to be made to lay down legislation—and put in place an effective implementing mechanism—to  regulate use of water and preserve the lakes in and around the city which are the only guarantee for retaining high water table under the ground. Nineteen tmcft of water is annually lifted/diverted from Cauvery to fulfill Bangalore’s water needs. Discord over sharing of the Cauvery water will not allow the BWSSB to draw more from it. Moreover, the cost of pumping water from that far and distributing it to homes in the city is computed at Rs 29 a kilolitre (i.e. 1,000 litres). Groundwater is fast depleting.

Contaminated water

There are a few more disconcerting facts emerging from recent studies that figure out pitfalls and prospects both. A report by the Department of Mines and Geology of the Karnataka Government reveals that 52 per cent of the borewell water and 59 per cent of tap water in the City is contaminated with sewage water and is unfit for drinking. Of the nearly 200 lakes once upon a time, barely 140 remain on the map, albeit for namesake and are gasping for breath. The Lake Development Authority(LDA), a toothless body, is viewed with grave scepticism by environmentalists who feel organisations like LDA are more often created to mask the reality of privatisation of the natural resources rather than to protect, preserve and develop them. It is pointed out that four prominent lakes in the city were handed over to private companies after they had been fully rehabilitated at the government cost.  Environmental activists apprehend that the ground has been officially paved for their eventual disappearance.

 So what can be done? Scenario is not all that gloomy. Water experts point out that the City fathers have not paid adequate attention to two more sources - rainwater and recycled water. Bangalore has on average 57 rainy days in a year with the precipitation bringing in 92 cm of rainfall in an average year. The city thus receives 21 tmcft of rainwater, two more tmcft than what it draws from the Cauvery. Of this, 3.6 tmcft falls over the roofs of 16 lakh properties which collectively cover 110 sq km or roughly one-eighth area of the city. This water is perfectly tappable by putting in place an effective rainwater harvesting (RWH)-compliant mechanism. This may appear easier said than done now. According to Principal RWH investigator at the Karnataka State Council for Science and Technology (KSCST), A R Shivakumar, the cost of tapping rainwater works out to Rs 2.50 for every one kilolitre once the initial pipe-sump infrastructure has been laid.

Even the rains falling on the open space (17.6 tmcft) can be made to flow into the water bodies and preserved. The option for recycling of water has not been explored yet. Large establishments such as the railways, defence, research institutes and industries should be asked to recycle the used water over and over again. In this context, a legislation such as permitting groundwater withdrawal commensurate to water recharge on the property for large establishment also needs to be thought of. KSCST studies suggests that the fresh demand on Cauvery water could be stalled and dependence could be cut to merely 50 per cent, if the authorities could conceive harvesting at least 20 per cent of rainwater, recycle 10 per cent of the waste water and leaving another 20 per cent for ground water. The chimera of living in an aquatically challenged city must propel us into action.