Ground water in many parts of Bengaluru urban and rural may be contaminated with carcinogenic nitrates, warns the Central Ground Water Board (CGWB).
A senior official of CGWB, who did not want to be named, said a detailed study was being conducted by a team of scientists and so far it has been found that ground water in most parts of Bengaluru is contaminated with nitrates. The permissible limit for nitrates is 40 milligrams a litre, but in most areas, the presence of nitrates ranges between 45 and 100 mg/ litre.
“Unsegregated waste being dumped around the city and leaking sewer lines are the cause. Since earth is not levelled, percolation happens and this leads to increased presence of nitrates,” the official said.
Nitrate contamination has been found near industries, areas surrounding ill-maintained sewer lines, around polluted lakes and market areas where waste decays, the official added.
According to CGWB officials, ground water in areas like Varthur, Bellandur, Ulsoor, Mandur, Mavallipura, Konanakunte, Doddakallasandra, Peenya, CMC and TMC areas, slums like Eijipura and areas around Shivajinagar, Majestic and City Market is contaminated. Officials from Bengaluru Water Supply and Sewerage Board (BWSSB) admitted that they received complaints of leaking sewers from many areas where the load is high on the old lines due to dense population. “Most complaints are from old and central Bengaluru like Majestic, Shivajinagar, Gandhinagar, M G Road, Church Street, Koramangala and densely populated areas,” a BWSSB engineer said.
A recent study by the Centre for Ecological Sciences, IISc, endorses these findings. The study, titled, ‘Groundwater Quality Impairment due to Mismanagement of Biodegradable Waste' explains this situation, said Prof T V Ramachandra, from CES, IISc.
Ramachandra noted nitrates are carcinogenic. Around 40% of Bengalureans consume ground water, 10-12% of which is contaminated. The city generates around 3,000-4,000 tonnes of waste every day, of which around 70% contain organic components. The degradation of organic waste releases gas and leachate, which is a serious environmental hazard.