If you were to head towards the northern part of the city and beyond you would have to take the Barrackpore Trunk road to reach your wonder destination. And while on the road it is almost impossible not to be fascinated by a tall colossal structure made of iron, which looks almost like an elevated abandoned aerodrome. Quite fascinating right?
Here’s presenting Tallah Tank – the world’s largest overhead reservoir. Propped by steel columns and girders, it is 110 feet high from its ground base and can hold nine million gallons of water. This marvel of a structure has developed only 14 leakages over 104 years of existence and despite widespread apprehensions of it falling down has withstood the World War II and the great earthquakes of 1934 in Bihar and Bengal.
In its early days, Kolkata was entirely dependent on its water bodies and the river for its watersupply. Pulta water works began in 1868 on about 482 acres of land to supply filtered water to the residents of the city. The filtered water was brought from the Pulta river side to Tallah Tank through a 42 inch cast iron pipe. At Tallah another pumping plant delivered the water partly to consumers and partly to another underground reservoir at Wellington Square which also had a pumping station.
Tallah Tank was a major achievement at the time for civil engineering and metallurgy, accomplished by Indian firms, though the design was by WB MacCabe, the then chief engineer of Calcutta Corporation.The water itself weighedabout 40,000 ton whilethe structure was about8500 tons. The land for the reservoir was donated by BabuKhelatGhoshsubsequently an adjoining lane was named KhelatBabu Lane.It had cost Rs 5 lakh during construction and the materials including the anti-corrosion plates were brought from England.
The unique feature of the tank is that no separate pipe lines are used for filling up and delivery. The pipe that fills the tank is also used for delivery. Hence, the overhead tank serves the role of a balancing tank. When the underground tank at Tallah is spilled over with the incoming supply from Pulta water works; (24 km upstream of Kolkata); the surplus water is stored in the overhead tank and again when the water level in the underground tank dwindles it compensates for the loss due to distribution. It seems to be that in order to add pressure to the gravitational flow of the water the overhead tank was placed at a height.
Standing at a height of 110 feet, it is 16 feet deep, spread over 321 feet square and divided into four compartments which are independent of each other and hence can be cleaned or repaired anytime without disrupting water supply.
Now that is surely an engineering marvel we, Kolkattans, can boast for a long time to come.
The images are not a property of The Beacon.