The growing water deficit

BWSSB faces an uphill task of providing water to the City as it has exhausted the Cauvery quota, and the water table too is depleting

There seems to be no immediate solution to address the increasing water needs of Bangalore as the quantity of water supplied to the City from various phases of the Cauvery scheme falls short of the demand.

Besides, the expanding City’s water table has been fast plummeting and, there are no alternative sources from which water can be supplied to the City.

With the commissioning of the Cauvery IV Stage Phase II project on October 31, the Bangalore Water Supply and Sewerage Board (BWSSB) has exhausted its quota of drawing water from the Cauvery basin. In all, Bangalore will get 600 cusecs of the Cauvery water per day (16 tmc a year) from all the schemes.

BWSSB supplies water to over six lakh houses in Bangalore, and the Board manages to pump in nearly 900 million litres of water a day (mld) from all the four stages of Cauvery water supply scheme. With the commissioning of the new project, 1,400 mld of water will be pumped to the City to a height of 1,000 metres from a distance of 100 km.

However, nearly 48 per cent of the water goes down the drain by the time it reaches the City, as the Board has not been able to plug the leakages. Therefore, just over 400 mld water is supplied to consumers, mainly residents of Bangalore South and East. Although BWSSB is taking up pipeline replacement work under the unaccounted-for water project in a phased manner, loss of water may still persist as many pipelines are five-decade old.

With the commissioning of the new project, the Cauvery water will now be supplied to the fringe areas of the City, including the newly added ones to the BBMP limits. The additional 500 million litres of water supplied through the new project is also expected to stabilise the supply in core areas of the City.

However, consumers to be benefited by the new project are yet to receive water supply as the Board is still conducting trial runs. But, water has already reached the ground-level reservoirs in the City.

New connections

BWSSB is expected to increase its house service connections to eight lakh. After a simplified application form, ‘Sajala’, was introduced recently, over one lakh application forms have been distributed and 30,000-odd consumers sanctioned new water connections. Although BWSSB claims to provide new connections in seven days after the filled-in application forms are submitted, at many places, it is taking more than a month.

However, 110 villages in the newly added areas will not get water as they are not part of the project. BWSSB initiated the Greater Bangalore Water Supply and Sanitation Project (GBWASP) in 2005 and created infrastructure for water supply in the newly added areas.

Depleting water table

Ground water, the other alternative source, is fast depleting in Bangalore and surrounding areas due to over-exploitation and indiscriminate sinking of unauthorised borewells.  The newly formed Assembly constituencies such as Rajarajeshwarinagar, Dasarahalli, Bommanahalli, Krishnarajapuram, Mahadevapura, Byatarayanapura, Yelahanka and Kengeri were solely dependent on  borewells for their water needs.

Following the real estate boom and increase in construction activities in these areas, hundreds of borewells were sunk, many as deep as 1,000 feet.

 In 2009, the department of Mines and Geology conducted a study of Bangalore ground water quality and quantity by collecting over 3,000 samples from an area of over 800 sq km. The study said that nearly 31 per cent of the ground water samples collected were not fit for potable purposes. With borewells being sunk up to 1000 feet in many areas, the amount of total dissolved solids (TDS) and fluoride content in groundwater had increased, which meant that the driller had reached static resource to procure water after exhausting the dynamic resource from ground water.

Contamination of ground water was mainly due to the untreated sewage disposal into the natural drainage system (storm water drains), which resulted in the presence of nitrate, low and high values of pH, e-coli and total coliforms bacteria in drinking water. The study found that heavy metals were present in ground water, especially in Peenya Industrial Area. It was mainly due to the infiltration of effluents from industries. In many places at Peenya, warning boards have been installed instructing people not to use water from certain borewells that contain heavy metal.

Since ground water dynamics is a very complex system, it is difficult to analyse the depletion levels of the water table. However, if water is not found even at a depth of 1,000 ft, it means the aquifer has dried up. In such places, rainwater harvesting and ground water recharging methods are recommended to be adopted by the residents to help replenish ground water.

After a survey on the ground water condition in the State, 35 taluks as well as the Bangalore Urban district and the City were declared “notified areas” under the Karnataka Ground water Act, which means that there has been over-extraction of ground water, and any activity regarding sinking of new borewells will need permission from the authorities.

There are 9,77,702 irrigation borewells and 2,51,797 borewells for drinking water purposes in the State. Bangalore City alone has three lakh-odd borewells (both government and private), which has no monitoring authority.

District committees were constituted in August this year to ensure effective implementation of the Karnataka Ground water Act. The rules guiding registration and permission for sinking borewells will come into force from December 3, 2012. 

As Bangalore City also comes under the notified area, the Karnataka Ground water Authority has proposed to fix meters to check over-extraction and impose a flat rate for every kilo litre of over-extraction of water. As  a few days are left for implementation of the Act, many borewells have been sunk at a fast pace in the newly added areas of the City. 

With rapid urbanisation, Bangalore’s population as well as its demand for water are expected to increase in the coming years. With Bangalore getting its maximum share of the Cauvery water and, the water table in the City depleting quickly, the BWSSB has been forced to explore new sources. Although the BWSSB Act was amended to make rainwater harvesting compulsory in the City, only 43,000-odd houses have incorporated the system so far. The Board has formed an expert committee to find solutions beyond the Cauvery to meet the growing water needs of Bangalore.