The reservoirs in the Cauvery basin might be full, but in large parts of the city, taps have run dry. The paradox has played out for the Bangalore Water Supply and Sewerage Board (BWSSB), which has stopped pumping water to capacity on Monday and much of Tuesday. The reason is the increased ‘turbidity’ in the churning waters of the Cauvery river after its release from the Kabini reservoir.
In a release, BWSSB said the purification plants of Cauvery Stage 4, Phase II — which alone brings in 500 million litres of water per day (MLD) — at T.K. Halli had to be partially stopped as the gushing waters had increased quantity of silt.
Of the five pumps, pumping from two — which carry around 100 MLD — had to be stopped from Sunday night until the machines were cleaned. It was only on Monday at 4 p.m. that all pumps began lifting water.
“The unexpected release of water saw turbidity increase rapidly. This was unexpected. We had to close the pumps and clean the machines of accumulated mud. Our teams are on alert to address this issue if it comes up again,” said an official.
While ‘normal’ turbidity during summers is 10 NTU (Nephelometric Turbidity Units, which measures soil and other particulate matter in water) and less than 20 NTU after monsoon, it had gone up to 230 NTU on Sunday with the release of nearly 1.5 lakh cusecs from the four reservoirs of the Cauvery river.
“This is a record for the Phase II pumping station. Till now, maximum turbidity was around 170 NTU,” said an official who has been at the station since its inception in 2012.
Water supply affected
In effect, supply of piped water was stopped to areas coming in the seven erstwhile city municipal corporation (CMC) areas of Rajarajeshwari Nagar, Dasarahalli, Yelahanka, Bytarayanapura, K.R. Puram and Mahadevapura, and the Town Municipal Council area of Kengeri. This encompasses lakhs of households and offices.
Among those affected was the 520-apartment Jal Vayu Vihar near Kacharakanahalli, which relies on piped water supply, said a resident.
BWSSB officials said pumping had been normalised. A team is on stand-by for quick response if turbidity shuts down the stations again, while it may take till Thursday for the city’s water supply to return to normalcy.
