BMC roots for new pipeline leak detection method

Another official said pipeline leakages are the main reason for water contamination. “During the hours when there is no supply of water,sewage water from underground utilities can enter pipelines. This gets mixed with the pure water that flows through the pipes,causing contamination.”

In the helium method,the water supply pipes are pressurised with helium and leaks are identified by measuring its concentration; the highest concentration denotes a water leak. “A special rod is then inserted into the ground to map the area and track the place from where the helium is escaping. We then carry out repairs. Being an inert gas,helium does not react with the contents of the pipe,” said the official.

The hydraulics department now uses the ultrasound method in other wards. “It is very efficient but there should be less traffic on the road for this method to be a success. This is problematic because the supply hours are such that it coincides with peak-time traffic. The helium method is more accurate but we may end up drilling too many holes around the area to insert the pole for leak detection,” said the official.

Meanwhile,records on the number of water contamination complaints received since January 2012 do not reflect the helium method’s success yet. In the C ward,271 complaints were registered in the past three months alone. But not a single contamination complaint has been reported from the T ward. According to officials in the water supply department,contamination cases go up during the monsoon because of seepage of sewage and groundwater into old pipes.

Based on water contamination reports,the average percentage of unfit water samples between May 2011 and June 2012 went down from 24.64 per cent to 15.6 per cent. In 2009-10,unfit sample percentage stood at 26.1. The BMC tests approximately 1,000 water samples from across 24 wards in the city each day. The number of tested samples is increased during monsoon.

Till August 2012,around 3,600 water contamination complaints have been reported in the island city,western and eastern suburbs. Due to the use of old pipelines,known to cause contamination,the highest number of complaints — at 2,840 — have been reported in the island city. The western suburbs reported 666 complaints since January 2012,while the eastern suburbs reported a mere 91.