Bengaluru's water needs in 2031: Master Plan paints a grim picture

Faced with acute water shortage, particularly during the summer months, Bengaluru is struggling hard to cope . If this is the scenario now, how scary will it be in 2031? The Revised Master Plan 2031 document released recently by the Bengaluru Development Authority (BDA) offers some clues.

The scary part is this: To cater to the needs of a projected population of 20.3 million in 2031, the water demand will be 5,340 Million Litres per Day (MLD). This includes 3,920 MLD for domestic potable purposes and 2,745 MLD for non-potable and commercial purposes.

The RMP has stressed the need to finalise a perennial source capable of meeting the water demand till 2031 and beyond. “The estimated demand may be reduced in the long term by reducing the Unaccounted For Water (UFW) to 15-20%, implementation of Dual Pipeline System, use of lakes for water sourcing, etc.”

The document has put forward a set of short, medium and long-term proposals to meet the shortfalls by 2021, 2031 and 2051. The cumulative shortfall will be 69.45 TMCft by 2051.

One key proposal to address the shortage by 2021 is to reduce the UFW to 16%. To get an additional 12.88 TMCft of water from Cauvery within the framework of the Cauvery Water Tribunal Award is another proposal. This should be taken up in two phases of 500 MLD each, one immediately and the other after five years.

Rejuvenation of the Arkavathi catchment is a third short-term proposal. This can be achieved by diverting for the present, about 100 MLD (1.20TMC) from the Vrishabhavathi valley Sewage Treatment Plant (STP) to the Arkavathi catchment.

The mid-term proposals include diversion of water from Yettinahole and other streams to the catchment of TG Halli. This, the document indicates, will fetch 10 tmcft. Diverting water from Linganamakki reservoir to TG Halli will fetch another 10 tmcft. Long-term proposals include the construction of a reservoir at Mekedattu, further drawal of water from Linganamakki reservoir to Bengaluru and more focus on rainwater harvesting.

Currently, BWSSB draws about 19 tmcft of water from Cauvery to meet the city’s demand. The plan is now to get an additional 10 tmcft (775 MLD) as accorded by the Cauvery Tribunal to meet the water demand in the BBMP area alone. However, due to the high proportion of UFW, the document warns that the dependency on ground water will increase further. In the villages in and around the city, this trend will be particularly apparent.