The next time you let water from a tap run waste while washing your vehicle or expend extra litres flushing your toilet, it is worthwhile to keep in mind the mindboggling journey every drop of water makes before it reaches your tap. The first leg of the journey of this precious commodity is 95 km from the Cauvery river or 140 km from the Kabini river to Shiva Anicut. It then travels another 11 km to Torekadanahalli (T K Halli) in Mandya district and is then pumped 85 km through an incredibly complicated process to reach Bengaluru. Unlike major cities in India, which either have a water source nearby or have developed on a river bank, Bengaluru’s main water sources are all in the neighbouring districts, making the supply of water a highly complicated affair.
The Cauvery river flows through Mandya district while its tributary, the Kabini river, is in Mysuru district. With the city located 3,000 feet above sea level, the only way of reaching water to it is by pumping upwards of 1,500 feet from T K Halli. “Every day, the Bangalore Water Supply and Sewerage Board (BWSSB) performs Asia’s biggest pumping exercise to lift (1,400 million litres) water upwards to the city,” says Kemparamaiah, Engineer in-chief, BWSSB. A visit by Express to trace the journey of the water took us to the first point of contact: the Shivana Samudram Headworks or Shiva Anicut. Water reaches this headworks by travelling 95 km from the Krishna Raja Sagar reservoir built across Cauvery river. Water from the reservoir, a product of the architectural genius of Bharat Ratna Sir M Visvesvaraya, travels 45 km to Thirumakudal Narasipura (T Narasipur) and then 50 km to Shiva Anicut.
Water from the Kabini dam in H D Kote Taluk travels 140 km by gravity to touch the headworks. Built across the Kabini river, it flows 90 km to T Narasipur and then 50 km to Shiva Anicut. From Shiva Anicut, water is despatched to the Shiva Balancing Reservoir (SBR). It is from Shiva Anicut that two routes take the water to T K Halli. In the first, a open canal sends 570 MLD of water to Netkal Balancing Reservoir. It is from here that water is connected through pipes to T K Halli. Water supplied to the Cauvery Water Supply Scheme I, II and III stages are sent by this method. In the second process, water flows through an open canal up to 700 metres and then mammoth pipelines connect it to T K Halli. The Cauvery Water Supply Scheme Stage IV Phase-I and Phase-II gets 800 MLD of water through this route. The T K Halli Plant, provided with heavy security since the Cauvery protests turned violent on September 12, bustles with activity 24x7.
The water that enters the plant is first exposed to oxygen in the air using a Cascade Aerator. “Water sent through pipes tends to develop bacteria as it is being kept in a confined space. The oxidation process helps in maintaining a healthy level of dissolved oxygen,” explains an official here. The next step is that of chlorination, done in massive amounts. Since it is dangerous for staff working around to inhale chlorine, it is sent in a gaseous form through pipes. “The chlorine used is almost 300 kg per day, which would ensure no harmful organisms are left in the water,” he added. The water is further subjected to Alum Dosing, whereby Aluminium Sulphate is mixed to ensure right turbidity (clarity) levels of water. Filtration process follows wherein sand is used as filters. Water thus treated and filtered is despatched from T K Halli through mammoth pipes 500 feet upward to Harohalli. Mammoth pipes emanating high noise levels carry out the job. From Harohalli, water is again pumped 500 feet to Tataguni pumping station. Water from Tataguni finally enters Bengaluru City after it is pumped another 500 feet. The water is distributed from here to the 56 Ground Level Reservoirs from where it is distributed across the City and surrounding areas through water pipes laid up to your doorstep.