Growing demand prompts B`lore to promote dual use of water
With the population of Bangalore crossing the 7-million mark and the demand for water reaching 1.2 billion litres per day (BLD), the Bangalore Water Supply and Sewerage Board (BWSSB) has proposed the dual use of water – laying separate pipelines for supplying drinking water and recycling water for non-drinking purposes.
Initially, the focus will be on industries. At present, BWSSB supplies recycled water containing ‘biological oxygen demand’(BOD) between 20 per cent and 30 per cent (considered fit for washing, gardening and industrial purposes) to major industries around the city.
Similarly, it has worked out a plan with the Bangalore Development Authority (BDA) for laying separate pipelines to supply both drinking and recycled water under the dual water supply policy in new residential townships like Visvesvaraya Layout and Arkavathy Layout.
“Owing to the rapid expansion of the city, especially on the outskirts, the demand for water has risen to 1.2 BLD as against the available 930 million litres per day (MLD). Demand is likely to go up to 2.2 BLD by 2025. We have no option other than to promote the dual use of water. Bangalore is the first city in the country to undertake such an exercise,” BWSSB chief engineer T Venkataraju stated.
BWSSB has been forced to opt for the dual water policy as it has exhausted all available sources of drinking water. At present, it draws water from Tippagondanahalli reservoir (148 MLD) and Cauvery river (810 MLD). The Cauvery river cannot meet the requirements of the growing city. This has forced BWSSB to restrict domestic water supply to alternate days.
The water shortage is aggravated by a huge share of water going unaccounted – as high as 38 per cent – due to illegal tapping and leakage. Therefore, the actual supply of water to consumers is approximately 530 MLD.
In addition, the ground water draft (through borewell and open wells) in the city is estimated at 750 MLD. Despite many plans and attempts, BWSSB has been unable to reduce the share of unaccounted water, especially due to political pressure.
BWSSB’s installed capacity to produce recycled water now stands at 70 MLD. By next year, it will increase to 245 MLD after the completion of work on tertiary treatment plants at various locations across the city. The potential to produce recycled water is approximately 800 MLD.
“This being the case, we will shortly launch a campaign to popularise use of recycled water among major industries. The Karnataka government is also trying to convince manufacturing and textile industries to opt for recycled water. In the next phase (starting date of which has not been decided), existing residential consumers will be targeted,” Venkataraju pointed out.
At present, BWSSB supplies recycled water to the Bangalore International Airport project (4 MLD), Bharat Electronics Ltd (1 MLD), Aravind Mills (0.5 MLD), Border Security Force and defence establishments (2 MLD). Recently, BWSSB won a contract to supply recycled water (48 MLD) to the upcoming power plant at Bidadi.
In the US and Australia lilac-coloured taps labelled ‘not for drinking’ are used for recycled water. “Under the dual water policy, separate meters will be provided for the recycled water supply. Nearly 60 per cent of water used in homes can come from this source,” Venkataraju explained.