IIT Roorkee: 52-million-litre tank needed to fix Malabar Hill reservoir

Members of the committee examining the reservoir on December 7, 2023

IIT Roorkee recently submitted its report on the Malabar Hill reservoir, suggesting that an additional tank with a capacity of 52 million litres is required to repair the reservoir in phases. This is exactly what IIT Bombay experts had recommended in March, but the suggestion was rejected by residents and experts. Brihanmumbai Municipal Corporation (BMC) officials will carry out a hydraulic study to reduce the size of the additional tank, which will result in the eventual removal of fewer trees.

Almost a year after commencing the construction of an additional tank for the reconstruction of the 144-year-old Malabar Hill reservoir, the civic body received another report from another Indian Institute of Technology. The experts from IIT Roorkee mentioned that three out of five subsections of the 80-million-litre old reservoir are in sound condition and do not require major repairs while the remaining two show signs of structural distress. For repairs, the sections have to be closed for months and an additional tank is necessary for the uninterrupted supply of water to surrounding areas.

Earlier, the BMC agreed to build a 90-million-litre tank for which 389 trees had to be removed. When the construction work started, residents opposed it and the BMC invited locals and IIT Bombay experts to study the structure. IIT Bombay submitted its report in March 2024 where it suggested building a 52-million-litre tank based on information provided by the hydraulic engineering department of the BMC.

"The current capacity of the tank is 80 million litres, which gets filled thrice a day to supply 240 million litres of water. A hydraulic study will be conducted at the BMC level to see if the supply can be managed with a smaller additional tank and increasing the number of cycles to fill it. The study will be discussed with IIT Roorkee for their comments," said Abhijeet Bangar, additional municipal commissioner. He added that the carbon footprint will be minimised with the size, shape and capacity of the additional tank.

80ml
Capacity of Malabar Hill reservoir

Reservoir saga so far

. The BMC initially planned to demolish and reconstruct the reservoir supplying water to south Mumbai by constructing a tank with 90 million litres capacity which required the transplantation of 200 trees and axing of 189 others

. A committee was formed on November 8, comprising residents and IIT Bombay professors

. Citizens' representatives submitted an interim report in early January favouring functional repairs over demolition

. In March, IIT experts recommended constructing a new tank with a capacity of 52.44 million litres to facilitate reservoir repairs or reconstruction

. The BMC invited IIT Roorkee experts to look into the matter. They inspected the reservoir's tanks on June 4

Malabar reservoir facts

. Comprises two tanks and five sections

. Has a combined storage capacity of 35.35 million litres in sections 1A, 1B, 1C.

. Total storage capacity in sections 2A and 2B is 39.17 million litres

BMC's next steps

. Conduct a hydraulic study within 10 days to see if they can manage with a lower-capacity tank

. Discuss hydraulic study with IIT Roorkee

. Float tender after taking decision

What IIT Roorkee report mentions

. No need to reconstruct existing tanks

. Repair is possible but either 1A, 1B and 1C together or 2A and 2B must be closed for this

. An additional tank with a 52.4-million-litre capacity is required for uninterrupted water supply to surrounding areas

. Sections 2A, 2B and 1A are in good condition and require minor repairs

. Sections 1B and 1 C show signs of structural distress and 1C requires major repairs