According to the report, 12.47% of drinking water in Mumbai is found to be contaminated this year compared to 9.05% in 2007. Kurla (L-ward) and Girgaum-Chira Bazar (C-ward) are getting the most contaminated water.

To ensure quality, water quality monitoring is carried out by the Brihanmumbai Municipal Corporation. Out of the 37,939 samples collected between April 2007 and March this year, 4,730 (12.47%) were found unfit for drinking.

The range of contaminated water samples is 6.21 to 17.27%. The maximum percentage of contaminated samples were found in L-ward (Kurla) which is 17.71% followed by the C-ward (Girgaum-Chira Bazar) that is 16.46%. The minimum percentage of water contaminated samples were found in P North ward. The contamination is in form of bacteriological contents, the report states.

How water gets contaminated

 BMC supplies water through service reservoirs, which is intermittent. This intermittent water supply is the root cause of contamination due to ingress of foul water during non-supply hours through joints. Disused connections, tampered mains, faulty fittings are the other causes of water contamination. 

 What measures does BMC take?

BMC takes adequate care to monitor water quality. Water is treated with pre-chlorination, alum-dosing, settling, filtration and post chlorination before it reaches to the consumer’s tap.

Water distribution system

The treated water stored in the master balancing reservoirs (MBR) and further distributed to 28 service reservoirs spread through the city by a network of inlet mains.
These service reservoirs in turn  supply water to citizens in different  water supply zones at suitable times for duration varying from 24 hours to 90 minutes depending on area and  topography.

URL: http://www.dnaindia.com/report.asp?newsid=1189532