Water reaches Mumbai from sources miles away

Water reaches Mumbai from sources miles away

By VINAYA DESHPANDE | Mumbai | 20 August, 2016
A view of the Tansa lake.
The Sunday Guardian tracks how water travels over 100 km, from seven dams, three purification centres and 28 service reservoirs to reach Mumbai homes.

Nothing makes a Mumbaikar happier than the news of cancellation of water cuts. Many Mumbaikars wonder why they have to face water cuts despite heavy rainfall. Many feel how come the catchment areas of the lakes that supply water to the city fail to replenish these water bodies despite heavy rains. We take you on a fascinating journey of water which travels from over 100 kilometres, and from seven different dams, to three purification centres, and to 28 service reservoirs, to reach your homes. Tens of villages in the Western Ghats have sacrificed their cultivable land and forests to fulfil the ever-growing thirst of the maximum city. “If people see how cumbersome the entire process of water supply to Mumbai is, they will never waste water. This should be shown in every school in the city,” said Trushna Vishwasrao, a Shiv Sena corporator and leader of the corporation’s House.

Today, Mumbai is supplied 3,750 million litres water per day. It comes from seven different reservoirs — Vihaar, Tulsi, Tansa, Bhatsa, Modak Sagar, middle Vaitarna and upper Vaitarna. Most of these reservoirs are located  over 100 kilometres away from Mumbai, a good 2-3 hours’ journey from the city. The water travels in pipelines over 6,000 kilometres. Many of these pipelines were laid over 130 years ago.

“Some of the dams that supply water to Mumbai were envisioned by the British. Some were started by us after Independence. The most recent is the work on middle Vaitarna, which was completed in the year 2014,” Ramesh Bambale, Mumbai’s Deputy Municipal Commissioner, told The Sunday Guardian.

How it all began

Till the 1800s, Mumbai was supplied water from the wells and ponds in the city. But in 1824, the city faced a severe water crisis. Water shortages thereafter tested the patience of the people. In 1845, a large protest was held against the government seeking supply of water. The British took these protests seriously and started scouring for places where dams and lakes could be built.

For the first time in 1860, Mumbai was provided water from a lake. The lake was Vihaar, which is situated on the Mithi river, and lies within the city’s precincts. Between 1860 and 1872, seven million litres per day (MLD) of water were supplied to Mumbai. Today, the city consumes over 3,700 million litres every day. By the year 1872, Tulsi dam was constructed. Tulsi too is located on Mithi river, and lies within the boundaries of the city. Due to the addition of Tulsi lake, the water supply to Mumbai jumped from seven MLD to 19 MLD. But even that was not sufficient.

“The British used to scour for location in the Western Ghats to construct a huge dam. They would visit the forts constructed by Shivaji Maharaj, and look around for valleys that can be converted into strong water storages to build dams. That is how they discovered the site of Tansa lake. Adjacent to this lake is a fort tucked in the mountains. The British identified this spot during their surveillance and search from that fort constructed by Shivaji Maharaj,” said Vijay Khabale-Patil, chief public relations officer of the Municipal Corporation of Greater Mumbai.

‘If people see how cumbersome the entire process of water supply to Mumbai is, they will never waste water. This should be shown in every school in the city.’

Tansa was completed in the year 1892. Located in Shahapur area of neighbouring Thane district, Tansa dam is at a distance of more than 110 kilometres from Mumbai. The location was chosen in such a manner that the mountains themselves act as check walls of the dam, and hold the water back. The wall constructed to hold Tansa is barely over three kilometres long.

“Tulsi, Vihaar, Tansa were constructed in the British era. Modak Sagar and middle Vaitarna were constructed after Independence. Capacity-wise, all three — Tansa, Modak Sagar and middle Vaitarna are similar. But the height of middle Vaitarna dam is the maximum at 102 metres,” Bambale said.

Asia’s largest treatment plant

The water that comes from these seven reservoirs is sent for treatment at three treatment stations in Bhandup and Pise-Panjarpur. Bhandup complex water treatment plant is believed to be Asia’s largest. Its filtration capacity is 2,100 million litres of water per day. Water coming from Tansa, upper Vaitarna and Bhatsa is treated at the Bhandup complex.

“Apart from Bhandup, we have Pise and Panjarpur treatment plants. In Pise, we have three pumping stations that lift water and send it to Panjarpur through suction plants. Panjarpur is eight kilometres away from here. The purified water is then sent to Yevai Hill which has a Master Balancing Reservoir. It supplies 120 MLD water. This filtered, chlorinated water is supplied to Mumbai through main lines which have a 2,345 mm dias,” said Sudhakar Hande, assistant engineer of Pise treatment plant.

Special feature: Water at negligible cost

Mumbai is supplied water through an intricate network of pipelines over 6,000 km long. But the beauty of this structure is that most of the water is transported by using the force of gravity. This ensures that very little amount is spent on electricity for pumping water to distribute it. Very few corporations in the country have managed to do that.

You get your water supply at negligible costs. The municipal corporation has identified 24 spots for construction of service reservoirs in a unique manner. Most of these reservoirs’ locations make it easy for the corporation to supply water with the help of forces of gravity. In most of the other municipal corporations, the water is transported by pumping. In such cases, the corporation has to spend additional funds for electricity to ensure proper pumping of water to the reservoirs.

“The secret lies in BMC’s identification of service reservoirs. They are located in such a way that water can be easily supplied by forces of gravity. There are very few places in Mumbai like Pali Hill or Malabar Hill where pumps are required to transport water. Those are the only places where the municipal corporation has to spend on electricity to transport water,” Hande said.

From the three treatment plants, water is sent to service reservoirs which cater to various parts of the city. Some of the service reservoirs are located at  Ghatkopar, Trombay, Rahuri, Powai, Borivali, Malad, Bhandup, Pali Hill, Malabar Hill. Most of these areas have two reservoirs — one is on top of the hill and one at its foot. They are called High and Low, e.g. Ghatkopar High and Ghatkopar Low.

The only corporation in the country to own dams

Mumbai Municipal Corporation is the only corporation in the country to have its own dams. Other places get water supply from dams owned by either the state government (irrigation department), or MIDC or Jal Pradhikaran. “In our case, of the seven dams, only two are owned by the state government. They are Bhatsa and Upper Vaitarna. But even in their case, the corporation has paid a share of the cost during their construction. The cost was arrived at on the basis of the calculation of water required by the city. The state government thus provides most of the water from these reservoirs for Mumbai’s consumption,” Bambale said.

Five reservoirs — Tansa, Modak Sagar, middle Vaitarna, Tulsi and Vihaar are owned and managed by the Mumbai Municipal Corporation. “Of them, Tusli and Vihaar are the small lakes. The rest are large dams. We have built our own dams and tunnels,” Bambale said.

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