Marginal dip in water contamination levels: BMC study

After five years of continuous decline in water quality,citizens finally have something to cheer. The water contamination levels in the city have fallen according to a study done by the Brihanmumbai Municipal Corporation for its annual Environmental Status Report. While the contamination levels have been steadily increasing in the past five years,the figure has come down,albeit marginally,between April 2010 and March 2011. However,the civic body admits that a lot needs to be done to reduce localised instances of contamination in the city. Compared to 2009-10 when 26.1 percent of samples were found contaminated,the figure has marginally come down to 24.64 percent for 2010-11.

The percentage of contaminated water samples for 2006-07,2007-08 and 2008-09 is 9.05 per cent,12.47 per cent and 13.80 per cent respectively. While officials in the hydraulic engineering department are unsure about the exact reason for the slight drop in contamination levels,they attribute it to the bulk of old pipelines being replaced with new ones during the past year. The highest percentage of contaminated water samples were found in the E ward that comprises large parts of Byculla,Chinchpokli and Mumbai Central. About 37 per cent of all water samples were found contaminated and unfit for consumption. L ward,comprising Kurla and Chunabhatti had 32.94 per cent of samples contaminated followed by A ward (32.50 percent) areas of Colaba,Cuffe Parade,Nariman Point,Fort etc and P south ward (32.24 percent) areas of Goregaon west. The contamination includes presence e-coli and other bacteriological content.

Hydraulic engineer Ramesh Bambale said water supply through service reservoirs is intermittent. “This is the main cause of contamination due to ingress of foul water from nearby sewer pipes into water pipelines during non supply hours,tampered mains and faulty fittings. Illegal connections by slumdwellers also result in large-scale contamination. Over the past year,we have carried out the work of replacing old pipelines in the city on a priority basis. This is could be a major reason for the marginal drop in contamination levels,” said Bambale. Mortar lining of about 47 km of pipelines was also carried out during this period.

Officials added the BMC’s 4,000-km water distribution network had a number of problems. The presence of coliform organisms occurs due to problems in the chlorination system at filtration and treatment plants. Water from the lakes is pumped to the Bhandup and Pise Panjrapur filtration plants. After a series of filtration procedures,the water is stored in 33 reservoirs across the city which is later pumped to homes through distribution lines. Some of the old reservoirs also add to the contamination,officials said.