T.G. Halli reservoir is back to life, but you can’t drink its water

The reservoir, with a storage capacity of 3.345 tmcft, has never filled to its brim since 1998

The good news is that Thippagondanahalli (T.G. Halli) reservoir, which was once a crucial drinking source for north and west Bengaluru, is back to life with 39.3 ft of water. The bad news, however, is that the water is undrinkable.

Bangalore Water Supply and Sewerage Board (BWSSB) is unable to draw from here as the water is unfit for consumption with high levels of total dissolved solids (TDS) and total organic carbon (TOC).

This summer, although top officials from the board had discussed the feasibility of treating the water through reverse osmosis and blending it with the Cauvery for supply to the city, in case of a water crisis, they dropped the idea as it would prove extremely costly.

BWSSB chairperson Tushar Girinath, who confirmed this to The Hindu , said the 1,350 mld water currently being drawn from the Cauvery was adequate to meet the demands of the city. “As the demand will grow exponentially in the coming years, we are planning the Cauvery fifth stage water supply scheme,” he said.

Visvesvaraya legacy

The 74-ft Arkavati-fed T.G. Halli reservoir, constructed in 1933 by Sir M. Visvesvaraya, was once a rich source of drinking water to Bengaluru. The board, which used to draw 60 million litres of water a day (mld) till April 2010, reduced it gradually to 20 mld because of depleting levels over the years. It stopped pumping from the reservoir when the water level plummeted to 6 ft in December 2012.

The reservoir, which has a storage capacity of 3.345 tmcft, never filled to its brim since 1998. It filled up to 61 ft in 2003 and subsequently the water level started depleting. Initially, the board was drawing 135 mld from here, recall old timers.

Poor run off

While officials attribute the poor run off into the reservoir to the rampant encroachment of the catchment area of the Arkavati, irrigation and water experts blame the BWSSB and the government for not implementing the rules.

“Although several Government Orders have been issued in the past that people should not drill borewells and develop layouts in the catchment areas, this has been happening continuously, thereby reducing the run off into the reservoir,” said Capt. S. Raja Rao, an expert in water issues, who is also the former Minor Irrigation Secretary.