Brihanmumbai Municipal Corporation (BMC) officials blamed the high level of water contamination in the city to the old distribution network, leaks and cracks in the pipelines.
The Hindustan Times collected 10 water samples from housing societies across the city and got them tested at the civic lab at Dadar. Six of the samples - collected from Chembur, Mahim, Andheri, Borivli, Bandra and Ghatkopar - were found to be unfit for drinking. They were contaminated with the A.aerogenes and coliform bacteria that cause stomach, intestinal and eye infections.
Hydraulic Department officials said on condition of anonymity as they are not authorized to speak to the media that the BMC supplies water till the main road of an area. From there, separate pipelines are laid to individual buildings. Contamination could occur in these pipelines too.
Even in the Environmental Status Report (2009-2010), the findings of which Hindustan Times reported on August 6, the BMC said there was seepage of sewage water into the supply pipelines, corrosion of the pipe and defects in valves leading. This led to an increase in the contamination level to 26.10% from 13.80% in 2008-2009.
"We will have to ascertain the source of contamination in these cases [the samples that Hindustan Times collected]. I will direct my officers to examine the spots," said Additional Municipal Commissioner Aseem Gupta, who heads the Hydraulic Department.
Officials also said that the BMC's 4,000-km water distribution network had several flaws. For instance, officials said, the presence of coliform organisms could be due to a problem in the chlorination system.
Water from the lakes is pumped to the Bhandup filtration plant. After a series of filtration procedures, the water is stored in 33 reservoirs across the city. It is pumped to your home from these reservoirs.
The reservoirs, officials said, were old and cracked, which too could lead to contamination. Gupta, however, ruled out contamination at this stage.
"Reservoir staff has been instructed to chlorinate water before it is supplied," said a hydraulic engineer.
Officials said work on replacing the old pipelines is being carried out on a war footing. Also, pipelines are being replaced with tunnels to avoid ruptures.
Rs 690 crore has been set aside for pipeline replacement and repairing reservoirs.
The 250-km, 100-year-old Tansa main, one of Mumbai's oldest distribution lines, ruptured over 300 times last year. Replacement work began in 2008, but so far only 42 km is complete.