Groundwater contamination poses a serious threat
Senior citizens in the City recall with much nostalgia how they drank water from the lakes in the City, and how the existing ones have turned into cesspools. Lake pollution contaminates the groundwater, which is one of the main sources of water for lakhs of Bangaloreans.
Large sections of the population, especially those living in the core areas, depend on Cauvery water. However, despite Bangalore Water Supply and Sewerage Board (BWSSB)’s daily tests before supply, contamination complaints continue to pour in. This is mainly due to the crisscrossing of sanitary and water lines. Such incidents are reported from the slum areas due to pipelines laid erratically by the consumers. Old and corroded sanitary lines only add to the problem, triggering health and hygiene related issues on a large scale.
V Balasubramanian, former additional chief secretary, cites laboratory results of the Public Health Institute and the Department of Mines and Geology, to inform that 52 per cent of borewell water and 59 per cent of tap water in Bangalore is not potable and contains 8.4 per cent and 19 per cent Escherichia coli (E coli) bacteria respectively.
He explains, “When water gets infected with E coli, it becomes a dire health hazard. The problem of diseases from public and borewell drinking water in Bangalore is seldom highlighted.”
External pollutants are mainly responsible for the groundwater contamination. According to Balasubramanian, there are about 312,000 borewells in Bangalore, from where about 300 million litres of water are drawn every day. The drawal of underground water is 3.7 times more than the recharge from 900 mm of Bangalore’s annual rainfall. This is the reason why the borewells have gone down to depths of 1,000 feet and beyond.
There is another disturbing fact. As many as 600 lakes in Bangalore Urban district have turned into sewage tanks, according to ‘Excreta Matters’, a report by Centre for Science and Environment, Delhi, 2011, a study that covered 71 cities in India. The sewage water contaminates the groundwater and percolates into the borewells.
In 2011, a report on groundwater contamination in Bangalore, prepared by the Department of Mines and Geology, made this startling discovery: Of the 3,000 samples collected, nearly 31 per cent was not fit for potable purposes. In places such as the Peenya Industrial Area, heavy metals, including chromium were found alarmingly high at 572 milligrams/litre (mg/l), much beyond the desirable limit of 0.05mg/l.
Over 250 small industries related to surface treatment, including electroplating, anodising, powder coating and degreasing in Peenya were draining out toxic effluents directly into the storm water drains. The effluents have percolated into the aquifer and contaminated the borewell water that turned greenish yellow. The water is considered carcinogenic and cause major health hazards including skin eruptions. The BWSSB has now barred the residents from using water from borewell and provided alternative supply through water tankers. The study also found other heavy metals such as zinc, copper, lead, manganese, and aluminium beyond permissible limits in borewells in industrial areas.
KSPCB Chairman Vaman Acharya
informs that certain electroplating industries in Yelahanka, Whitefield, Mahadevapura and Peenya are still discharging their effluents into the stormwater drains.
“We have given strict warning to these industries. We have also proposed a common Effluent Treatment Plant (ETP) in Peenya to curb the chromium menace,” says Acharya.
former additional chief
secretary, Govt of Karnataka
“Unless the sewage is diverted and the raja kaluves are cleared of encroachments to carry surplus rainwater to the succession of lakes, all the water bodies in Bangalore will become sewage cesspools, causing immense health hazard.”