Bengaluru’s water woes

Print edition : October 14, 2016

SITUATED at an elevation of around 3,000 feet (914 metres) above mean sea level, the fast-growing metropolis of Bengaluru, India’s information technology capital, still enjoys salubrious and mild weather for most part of the year, which, many believe, is the only reason why brand Bengaluru continues to stay afloat. But its elevation and hard-rock (granite-gneiss) terrain have also meant that sourcing water, especially for drinking, has always been a challenge. The closest perennial river, the Cauvery, flows over 100 kilometres away and at an altitude that is 1,000 feet lower than Bengaluru’s. The cost of pumping water to Bengaluru is around Rs.350 crore a year.

The early rulers and later the British devised a series of tanks that held rainwater flowing from higher ground. By some estimates, at one time the 2,200 sq km area that is today the Bengaluru Urban district had around 937 tanks, which were supplemented by private and public wells, including kalyanis or stepped wells. The committee of elders formed by the Maharaja in 1862 to look after the welfare of the people arranged to supply water to the town through channels from the Dharmambudhi, Sampangi, and Sankey tanks.

In 1882, with the city’s population crossing one lakh, the Dewan of Mysore, K. Seshadri Iyer, persuaded the British and the Maharaja of Mysore to agree to construct the city’s first potable water supply scheme, the Chamarajendra Water Works. It was decided to construct a reservoir at Hesaraghatta across the Arkavathy, a tributary of the Cauvery, with a storage capacity of around 900 million cubic feet, which would be sufficient to provide the city with water for three years. The water was carried through an open channel by gravity up to Soledevanahalli where it was pumped by steam-driven pumps into huge cast iron pipes that conveyed the water to the Combined Jewel Filters storage in Bengaluru, where it was filtered and let into the distribution system.

Commissioned in August 1896, the reservoir cost Rs.19 lakh. Over the years, urbanisation in the catchment area drastically affected inflows into the Hesaraghatta lake. In 1922, the Hesaraghatta reservoir dried up for almost a year owing to a severe drought.

The next project aimed at supplying water to Bengaluru was the Chamarajasagar Dam Scheme, popularly known as the Thippagondanahalli dam. By 1933 a reservoir was constructed at Thippagondanahalli, downstream of Hesaraghatta at the confluence of the Arkavathy and Kumudhwathi rivers at a cost of Rs.55 lakh and it was hoped to supply six million gallons a day of water to Bengaluru. But over the decades, inflow into the reservoir came down significantly, thanks to change in land-use patterns, inconsistent rainfall, intensive groundwater irrigation and blocking of secondary and tertiary nullahs or valleys. At present hardly any water is drawn from Thippagondanahalli.

With Hesaraghatta and Thippagondanahalli reservoirs way past their by use-by date, Bengaluru will in the years to come be dependent almost entirely on the Cauvery for its drinking water needs. City planners have also come to the conclusion that only water from the Cauvery can offer the city a long-term solution. Water was drawn for Bengaluru from the Cauvery at the Shiva Anicut, over 100 km away, with the first stage commissioned in 1974. Over the decades, three more stages were commissioned and today the total drawal of water from the Cauvery for Bengaluru, at around 1,350 million litres a day (mld), is 19 thousand million cubic feet (tmc ft) against the current demand of 1,575 mld for a population of 1.12 crore and growing. The Bangalore Water Supply and Sewerage Board (BWSSB) spends Rs.350 crore a year, which is more than half its annual budget, to pump the water to Bengaluru.

According to a former managing director of the Karnataka Urban Water Supply and Drainage Board, planners have not been able to meet the ever-increasing demand of the burgeoning metropolis and the only option is to get more water for Bengaluru from the Cauvery. But the State cannot draw more because there is no scope for it under the Cauvery Water Disputes Tribunal’s award.

Said a senior bureaucrat: “Bengaluru needs over 40 tmc ft, or at least 135 litres per capita per day (lpcd). We are getting 19 tmc ft. In fact, we took up the Cauvery Water Supply Scheme Stage-IV, Phase-II, in order to meet the ever-increasing demand of Bengaluru city, particularly in the erstwhile city municipal council (CMC)/town municipal council (TMC) areas which were merged into Greater Bangalore [Bruhat Bengaluru Mahanagara Palike, or BBMP] in 2007. This project was taken up by the BWSSB to augment water supply to the city by 500 mld at a cost of Rs.1,759 crore with funding from the Japan International Cooperation Agency (JICA), the Government of Karnataka and the BWSSB. We have other schemes and funding to the tune of Rs.5,100 crore by the JICA, but we need to have the water for that. We are hoping to get relief from the Supreme Court when our case comes up on October 18.”

Though assessors wanted Bengaluru’s estimated population in the year 2051 to be the basis for allocation from the Cauvery, the CWDT in its wisdom decided to take 2011 (when the population was just over 84 lakh) as the year of reckoning. It limited water to 100 lpcd for 25 per cent of the population and 135 lpcd for the rest of the population.

Bengaluru consumes 50 per cent of the Cauvery water reserved for domestic use in Karnataka. Ironically, about 46 per cent of the 1,400 mld of water pumped to the city, or 600 mld, is lost in distribution, and is called “non-revenue water” or “unaccounted for water”. According to BWSSB officials, wastage is of two kinds: damage and leakages in the water supply system, which account for over 88 per cent of the wastage, and, second, unauthorised water connections.

According to Ashwin Mahesh, a former Antarctic climate scientist, who presented a paper to the government titled “One more Cauvery”, the 1,350 mld of water that Bengaluru gets from the Cauvery can be more than doubled, to 2,800 mld or even 3,000 mld, by reducing losses, improving rainwater harvesting, recharging groundwater, insisting on dual piping for new multistoried buildings and reviving and improving the watershed of the city’s lakes and tanks.

According to data from the BWSSB, by 2031 Bengaluru’s water supply will reach its optimum level of 2,070 mld.

Ravi Sharma