Mumbai Water supply

The huge lakes in and around Mumbai feed the city’s thirst – for water, power and entertainment. Dancewithshadows tests the waters.

For Mumbai’s population of 18 million people, water is the most precious commodity. The metropolis cannot take its first step in the morning and end the day without it. The water supply for Mumbai which comes from six lakes within Mumbai’s precincts has grown over the last 130 years.

These six lakes are being Tansa, Modak, Bhatsa, Vaitarna, Tulsi, Upper Vaitarna and Powai. The system is supported by reservoirs, storages, pipes and taps till they reach the citizens The city in fact, is inundated with creeks and bays.

Set in picturesque surroundings, two of these lakes are within the Sanjay Gandhi National Park, the only wildlife sanctuary within city limits. Powai is bang in the middle of an industrial zone today. All are and have been picnic spots for the Mumbai’s citizens. Except for Tansa, Vaitarna and Upper Vaitarna which lie on the outskirts of the city, which you are likely to see only while travelling on outstation-bound trains, when it crosses the bridges over these lakes.

It was in 1856 that the first lake – Vihar was earmarked to be used as a source of water supply by Captain Crawford of the Engineers in a report to John Lord Elphinstone. The initial supply was just 32 million litres a day. The cost: Rs 65 lakh. 

The supply has been increased every now and then. Vihar is located at the origin of the Mithi river and three earthern dams and the overflow section in stone masonry are built here. The plan for Tulsi lake was laid in 1872-79 by damming and redirecting river Tasso into Vihar lake at a cost of Rs 40 lakh. Tulsi Dam was built over a hundred years ago and the forest surrounding it acts as a catchment area. These two lakes can be visited with special permission only.

In 1884, Tulsi and Vihar waters were still insufficient so the Tansa water works was sanctioned. It has one of the largest masonry dams in Asia and was designed by Major Tulloch in 1872. It was completed in 1892 and supplies 410 million litres daily to the city. 

Powai was commissioned when Tansa work was underway and a water famine seemed imminent. This source was developed over four stages and the dam celebrated its centenary year in 1991-92. The Powai valley scheme on the Mithi River was sanctioned as a supplementary to Vihar and work began on it in 1889 and was completed in 1891. Its inferior quality of water, led it being used for other purposes rather than drinking – agriculture and Vaitarna (the lower) was planned and conceived by a group of municipal engineers. This river comes from Trimbhakeshwar in Nasik, and a dam Modak Sagar was built across it in 1957. 

Upper Vaitarna is used for the supply of water and hydro-electric power. Water from here flows to lower Vaitarna after generating power and water is then supplied to Mumbai. A dam upstream conveys the water downstream and is built of concrete masonry. This project was completed in 1972. 

It is the Western ghats that trap the monsoon clouds that feed these lakes. With the lakes, many reservoirs also exist such as the one at Malabar Hill, which has a garden that stands above three of them that store 300 lakh gallons of water.

Every college and school student in Mumbai has visited Vihar lake for a picnic than many care to mention. It has a pumpkin house, shoe house and a place where the overflow from the dam is collected and used as a slide from top to bottom, a height of over 25 feet. This is one of Mumbai’s favourite picnic spots. 

Powai is well known for its boating rides which have been curtailed due to the growth of creepers across its water and dumping of garbage. Vaitarna, Upper Vaitarna, Tansa, Bhatsa are as vast as the sea and are used by fisherman to collect fresh water fish. Their boats are a regular sight on and off the lakes or on the banks. 

Two of the lakes lie within the Borivali National Park/Sanjay Gandhi National Park. There are a six to seven miles walk from the parks main gate or you could easily drive down in your own car. Rickshaws and cabs are forbidden to enter the park now. A 104 sq km of virgin forest land is waiting to be explored. The park within its limits holds many species of birds, animals, plants, trees and flowers. It makes for a quiet journey away from the grime, dust and the noise of the city.

In summer months, the place is a riot of colours and during rains, the green forest holds a charm of its own. Streams tumbling across various paths to reach the lakes, ponds and rivers. The green carpet and cool atmosphere becomes a virtual paradise. Nature trails provide the openings to the secrets of the deep forest. 

The southern part of the city is getting water through Malabar Hill reservoir and Bandarwada Reservoir but the rest of the city is getting direct water from the mains. The Ulhas River Scheme was brought on in 1965 in an emergency. This added to the city’s water supply but this source was handed over to Kalyan Municipal Corporation in 1994.
The water supply to Mumbai from various sources is about 563 million gallons per day (MGD). The lakes – their normal levels at the end of the monsoon, as well as the amount of water supplied to the city per day… 

Lake Level (m) Supply (MGD)
Bhatsa 122.36 23.5
Upper Vaitarna 603.50 140
Modak Sagar (Lower Vaitarna) 163.15 100
Tansa 128.63 90
Vihar 80.42  –
Tulsi 139.17  –

The water distribution system in Bombay is also about a 100-years-old. Water is brought in from the lakes after treatment, and stored in 23 service reservoirs. The two major sources, Tansa and Lower Vaitarna, are at a higher level than the city, not much power is required to pump the water. 
The service reservoirs are mainly situated on hills as mentioned earlier are located at Malabar Hill, Worli Hill, Raoli, Pali Hill, Malad, Powai and Bhandup. The timing of water supply to different parts of the city vary between two to five hours. 
Currently, the Mumbai Municipal Organisation (BMC) earns above Rs. 4.5 billion a year through water charges and levies. Water production costs Rs. 24 per 10,000 litres, they charge Rs. 6 for 10,000 litres for domestic consumption, and have a system of cross-subsidy whereby they charge Rs. 150 for 10,000 litres for industrial and commercial users.

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