Heavy metals contaminating Bangalore’s groundwater resources

Here comes a shocker for Bangaloreans on the water front. Only 0.9% of the groundwater in Bangalore is fit for consumption, while the remaining is contaminated by heavy metals, a study conducted by the mines and geology department, and released on Wednesday, has revealed.

Only on Tuesday, the Bruhat Bangalore Mahanagara Palike (BBMP) had said that residents are demanding about 1,511 new borewells — a far-fetched dream from the latest revelation.

While the quantity of potable water has gone up from 31% to 50% when compared to the study done in 2003, however, when it comes to coliforms, the concentration of metals has gone up considerably making the population, especially of peri-urban areas, vulnerable to a host of health problems. Coliform contamination had reduced in the last few years due to sewage treatment initiatives. However, industrial pollution had continued unchecked, officials said.

The study titled ‘Urban Groundwater Hydrology and Groundwater Quality in and around Bangalore City’ was funded by a soft loan of Rs16 crore by the World Bank and initiated in May 2010.

About 3,000 samples in the BBMP limits were tested. “Among the 2,209 groundwater samples analysed, the nitrate content in excess of the desirable/permissible limit is found in 638 samples (29%), iron in 214 samples (10%), total hardness in 185 samples (8.5%) and fluoride in 14 samples (0.6%). Excess fluoride was found in samples from Bellandur and Bidarahalli. Instances of dental and skeletal flourosis were also common,” said chief chemist MN Shashirekha, who led the analysis of samples.

Areas such as Nayandahalli, Sanjay Gandhinagar and Old Yelahanka tested positive for nitrate. “Deflouridisation cannot happen, as the waste is difficult to dispose. Rainwater is the best. Do not opt for reverse osmosis to soften water as it removes all minerals. Consuming hard water might give you kidney stones, but drinking soft water puts you at risk for hypertension and heart attacks,” she said.

The results of the study will be sent to agencies such as the Bangalore Water Supply and Sewerage Board and the Pollution Control Board to take action. “We are merely referees who can point out the status of groundwater. The overall exploitation of groundwater in the state is 68%. In Bangalore, it is 120%. We have lost the resources completely. The way forward could be to close borewells and supply water through tankers. Recharge wells is the way forward,” said HR Srinivas, director, mines and geology department.

The results will also be uploaded on the web for citizens’ benefit.
Krishnamurthy from the department of rural development and panchayat raj said that the government was considering colour-coding borewells to indicate their health. By looking at the paint on the borewell, one would be able to tell whether it is defunct, if the water in it is polluted with coliforms, metals etc.