Water Management of Mumbai
-Vidhiti Shah, Vaishnavi Hirpara
Colonial Water pipelines in Mumbai (Image Credit: Mohammed Esa Shaikh)
Today, a simple turn of the tap provides clean water, a precious resource. Engineering advances in managing this resource—with water treatment, supply, and distribution systems—changed urban life profoundly in the 20th century. Urban water management involves the planning, design, and operation of infrastructure needed to meet the demands for drinking water and other domestic uses.
The city is divided into nine municipal wards within the Mumbai City district, and fourteen wards within the Mumbai Suburban District, all of which need to be supplied with water in a timely manner. The water management of Mumbai city comes under the purview of the Municipal Corporation of Greater Mumbai (MCGM). For building or upgrading new water supply lines, contracts are given to contractors on the basis of tenders filed.
Mr. Upesh Shah, a contractor, describes the water supply system: “The water distribution system in Mumbai is about a hundred years old. Water is brought into the city from the lakes after treatment. It is stored in 28 service reservoirs, Malabar hill, Worli hill, Raoli, Pali hill, Malad, Powai and Bhandup being some of them. Water supply to Mumbai city is dependent on six lakes as well. These lakes are Tulsi, Vihar, Tansa, Upper Vaitarna, Bhatsa, Modak Sagar and Mumbai III.” Greater Mumbai has all its major surface water reservoirs located in surrounding districts on the basin areas of the major rivers-Vaitarna, Ulhas, Patalganaga and Amba. Tulsi and Vihar lakes are located within city limits and their water treatment plant is at the same location. The other reservoirs are around 100 km away from the city and their water treatment plants are located in the Bhandup and Panjarapur treatment works.
Vihar Lake (Source: Wikicommons)
He also talks about the process of water treatment, “The water goes through a five-stage process of purification which consists of pre-chlorination, alum dosing, settling, filtration, and post-chlorination. Also, the water is backwashed to clean the filters. The backwashed water generated at Bhandup treatment works (45 MLD) is released into Vihar Lake and the backwashed water at Panjarpur treatment works (20 MLD) is discharged into nallahs (drains). Treated water is stored in Master Balancing Reservoirs (MBRI) at Bhandup Complex (246 ML) and MBRI at Yevri (123 ML), and further distributed to 28 service reservoirs located in the city through inlet mains.”
A sketch of the water distribution process (Drawing: Vidhiti Shah)
The department in charge of these functions at the MCGM is the Hydraulic Engineering Department of MCGM in Greater Mumbai. It consists of one Hydraulic Engineer (H.E.), who is head of the water distribution system, and twelve Deputy Hydraulic Engineers. There are lacs of water connections in Mumbai, all expertly handled by these engineers. Water transmission (650 km) and service pipes (3200 km) cover the entire city. Water supply and water pressure to each ward is dependent on the total water availability. Nearly 83 percent of these connections are domestic connections including slums. Commercial connections are 15 percent. Industrial connections are very low, only 2 percent in the city. There are around 15000 un-metered water connections in the city, and those escape the purview of the engineers, being managed instead by their own informal economy of plumbers, vendors etc.
Groundwater in Mumbai, though plentiful, is considered to be unsafe by the MCGM. In order to mitigate the risk of epidemics, the MCGM had banned the use of water from wells and ponds for domestic use. However, due to the increase in population and the stress on water supply to meet the water demand groundwater is seen as a supplementary source of water during shortfall. There are 3950 dug wells and 2514 bore wells under operation for water supply purposes in the city.
Mumbai still experiences extreme water shortage in many parts of the city, mainly in summers. “This happens due to the population density of Mumbai. In informal settlements millions of people are living in a very compact way. The MCGM considers an occupancy of 5 people in each house but the number of people living in these slums and their subsequent need for water far surpasses their estimates,” says Mr. Shah. Also, lakes in Mumbai overflow in the monsoons, but with no area to build additional reservoirs, Mumbai has limited holding capacities. Further, an immeasurable amount of potable water is lost in a number of leakages in the colonial pipe systems. “Either pipes are joined by welding or a rubber joint. Leakages of the pipe can be checked by connecting the pipe with a pump and adding water to the pipe with a pressure gauge attached on the top to check pressure. If the pressure is not found to be the same as the standard pressure then the pipe will have leakages,” says Mr. Shah on a possible reason for the leakage problem.
Mumbai 2005 floods (Source: Hitesh Ashar, Wikicommons)
Mumbai’s water shortage is particularly ironic when considered in the context of recurring floods in the city. For this, Mumbai’s polluted rivers with their poor draining capacities are frequently blamed. Another reason for this is the poor management of Mumbai’s storm water drains. In some parts of Mumbai, the drainage system is of British era, which is capable of handling only 25 mm rainfall before inundating. Mumbai receives an annual rainfall of about 2146.6 mm, one of the highest in the country. In addition, the threatened ecosystems of our mangroves and estuaries further lower our risk capacities of flood management. It may seem cruel that water is everywhere, except in our taps – and the journey it makes from the skies to our homes seems to be getting lost in the convolution of our water management.
Vidhiti Shah (19) and Vaishnavi Hirpara (21) are both students of architecture at the IES college of Architecture.