The civic Environment Status Report (ESR) for 2009-2010 blamed the doubling of contamination levels in drinking water largely on Mumbai’s century-old pipelines.
The report gave several reasons for the rise in contamination: leaks in distribution lines, cracks and undetected contamination in pipes in houses, seepage of sewage into drinking water pipelines, unclean storage tanks in homes, corrosion of pipelines and defective valves. “Plugging these contamination sources (sic) will pose a challenge to the civic body,” said the report.
Officers from the Hydraulic Department refused to comment on record as they are yet to receive the report. An official, speaking on condition of anonymity, said: “As the report stated, the main cause of contamination is that the distribution network is prone to pipe bursts and has developed several cracks, leading to seepage.”
The annual report, accessed by the Hindustan Times, said the contamination level rose to 26.10 per cent in 2009-10 from 13.80 per cent in 2008-2009.
There was also an increase in contamination levels at Mumbai’s reservoirs, from 10.10 per cent in 2008-09 to 22.60 per cent in 2009-10.
“We try to redress contamination complaints within 24 hours, but sometimes due to the proximity of the pipes water from sewage lines seeps into the drinking water pipes,” said an official.
Officials claimed that work on replacing old, corroded pipelines is being carried out on a war footing. Many pipelines are being replaced by tunnels, which are easier to maintain and less prone to ruptures. This year, Rs 690 crore has been budgeted for replacing old pipelines and reconstructing old reservoirs.
The 250-km Tansa main is one of the oldest distribution lines and ruptured over 300 times last year. Replacement work on it began in 2008 but so far only 42 km has been replaced. That’s because, while replacement work is on, water supply needs to be shut. There are few time slots when that can happen. Also, the civic body has never carried out such a project before, and its lack of experience is showing.