Wednesday, July 30, 2008

The long journey of City's water

The long journey of City's water
S Lalitha
Every glass of water you drink reaches your doorstep after a long and fascinating journey. The story of that journey ought to be told as long as Bangalore thirsts for the precious commodity.

In a unique phenomenon which takes place only in a few spots in the world, water is brought to the City from a distance of over 100 Kms from its perennial source, the Cauvery and the Arkavathi. The intake point from Cauvery is the Shiva Anicut. It is gravity which makes water flow from Anicut to the Netkal Balancing Reservoir (NBR), located 8.5 kms away. The NBR transports water to water treatment plants at Thorekadanahalli or T K Halli through mammoth 1750/1950 mm dia mild steel pipes running to a length of 9.6 kms. Located in Malavalli taluk of Mandya district, T K Halli is the centre of the entire City’s water supply. Situated on the banks of river Shimsha, it is 87 kms from the City at an elevation of 600 metres above mean sea level. The Muttathi forest range envelops the area, lending much serenity to the place.

Spread across 425 acres here are the pumping stations, pure water tanks, filtration units, staff quarters and offices. Water is treated at the water treatment plants here. These plants are constructed under the Cauvery I, II, III and IV stages. The Stage I commissioned during 1973 is equipped with five pumpsets and supplies 135 Million Litres Per Day (MLD). The Stage II, commissioned during 1982, has an equal number of pumpsets and supplies another 135 MLD. The third and fourth stages, commissioned during 1993 and 2002 respectively, have each been equipped with eight pumpsets and each one supplies double the capacity, 270 MLD each.

The first three stages are equipped with water treatment units which uses the conventional treatment process and uses rapid sand gravity filters. The first phase of the IV stage has an advanced water treatment process which makes use of the latest French technology. It consists of pulsators, clarifiers and Aquazur V filters. Recognised as one of the best treatment plants in the country, the water treated here meets international standards.

The treated water is then pumped against a head of 160 mts at each stage of pumping. The pumping is done at the points at Harohalli (34 kms from the City) and Tataguni (26 kms). This is done through 1200/1650 dia mild steel transmission pipes to Bangalore and then distributed to various reservoirs.

These processes ensure the City receives 810 MLD per day. In addition, the Thippagondanahalli reservoir, located 30 kms from the City, provides another 60 MLD daily. To augment the water supply, a boosting station has been set up to supply another 100 MLD to the newly added BBMP areas, which is yet to be commissioned.
However, present shortage and the growth of the City will require much more water. To supply an additional 500 MLD, the second phase of the IV stage will begin work this December with assistance from the Japan Bank for International Cooperation. This project, to be built at a cost of Rs 3383.70 crores, is likely to be completed by 2011. The City is then slated to receive drinking water on a daily basis, in place of the alternate day or three days a week supply, which is the norm in many areas now.


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