Water warning still holds

Barely a week after an alarmist BBC report warned that Bengaluru will be the next city to run out of water, the Cauvery verdict comes as a relief. Yet, the allocation of an additional 4.75 TMCFt of water for the city does little to reverse a disturbing trend: Lack of any serious, concerted attempt to recharge the groundwater table, rejuvenate lakes and treat and reuse its waste water.

Backed by well-researched studies, scientists have clearly indicated that if a well structured recharge-recycle-reuse policy is in place, Bengaluru can potentially be a water-surplus city. But half-hearted measures with little planning have left the city in an inglorious mess. To make it worse, over 40% of the Cauvery water supplied in the city is lost due to inefficient distribution and pilferage.

Antiquated plumping system

The BBC report had dubbed the city's plumbing system as 'antiquated' and in need of an urgent upheaval. Citing a 2014 study, the report also observed that the city loses over half of its drinking water to waste. The Bangalore Water Supply and Sewerage Board (BWSSB) has since clarified that the extent of Unaccounted For Water (UFW) is now down to 39%.

Ironically, the 'going dry' warning comes for a city that receives an estimated 700-850 mm annual rainfall. Last year's rains alone broke several decades-old records. Harvesting this rain efficiently will be enough to meet almost 70% of the city's water requirements, notes Dr T V Ramachandra from the Indian Institute of Science. His reports have repeatedly driven home this point.

Lake rejuvenation

But rainwater harvesting is not limited just to rooftops of individual houses. To make a real impact, the lakes should be rejuvenated so that rainwater is retained within. This should aid recharging of the groundwater, says Dr Ramachandra. "In 1800, Bengaluru had 1,452 water bodies in the existing 741 sqkm area of BBMP. Today, we still have 193 such water bodies, almost one in each BBMP ward. Efforts should start locally to retain water," he explains.

Meteorological data indicate that the rainfall in Bengaluru is on the rise. This is a recent phenomenon, as A R Shivakumar, Principal Scientific Officer at IISc's Karnataka State Council for Science and Technology informs. "Hundred years of rainfall statistics puts the average annual rainfall at 929 mm and 57 rainy days in Bengaluru. Considering the average roof area available for rooftop rainwater harvesting per property at 110 sqm, the potential for rooftop RWH is 81,752 Million Litres (at 80% collection efficiency).

Disappearing funds

There is no dearth of plans to rejuvenate lakes and push RWH in a big way. But ground reality is far from rosy. Funds earmarked for rejuvenating lakes and recharging groundwater have disappeared. Roads and pathways are being asphalted or concretised without leaving enough space for rainwater to seep in. It is estimated that every year, at least 23 TMCFt of rainwater goes down the drain.

However, buoyed by the Cauvery verdict and anticipated inflow from future projects, BWSSB is upbeat. Days before the verdict, Bengaluru Development Minister K J George had informed that by 2023, the city will get an additional 775 MLD (Million Litres Daily) from the Cauvery allocation. This will now go up. Besides, the Yettinahole project will provide another 193 MLD by 2021.

Also on the government's agenda is a project to draw water from the Linganamakki dam across the Sharavathi river. Articulating this confidence, BWSSB chairman Tushar Girinath says by 2031, even if Bengaluru's population grows to two crore, the freshwater supply per person will be around 88 litres per day. Water loss will be an estimated 25%.

Groundwater depletion

But the dependence on groundwater in areas not served by BWSSB's Cauvery water has already done enough damage. Over a decade after they were brought under the BBMP's jurisdiction, 110 villages around the erstwhile Bangalore Mahanagara Palike (BMP) are still without Cauvery water connection.

In all these years, thousands of borewells have been drilled by residents, water mafia dons and BBMP corporators, dangerously depleting the groundwater table. In Mahadevapura, Whitefield, K R Puram, Bommasandra and other peripheral areas, water is not found even at depths of 1,500ft. Besides, as geologists say, groundwater below 30 metres are highly prone to chemical pollution.