Bacteriological survey of drinking water in Karachi

Karachi is one of the twenty mega cities of the world having population of about fourteen million and covers an area of more than 800 square kilometer. In this city supply of clean water is a continuous problem and this dilemma is increasing day by day due increase in population, insufficient supply of drinking water and pollution. Present study was design to check the quality of drinking water in terms of bacterial contamination. Sampling was carried out in collaboration of KW and SB. All required microbiological experiments were carried out in Microbiology Lab. Total 100 water samples were collected from pumping station of KW&SB lies in different localities of Karachi with high, intermediate and low socioeconomic condition. Samples were collected in sterilized container as per WHO guidelines (2008). 2ml of 10%sodiumthiosulphate was used in each sampling container to neutralize any residual chlorine, these water samples were transported in ice box to microbiology lab within two hours of collection. All the samples were tested for total viable count and total coliform count by hrtotrophic plate count and most probable number (MPN) method. Enrichment media were used for isolation of E. coli, Salmonella spp and Vibrio spp,. Indigenously developed rapid identification system - QTS-24 strips were used for biochemical characterization. In total of 100 samples, 60% samples were found highly contaminated. 28 different bacteria related to GIT infections (E Coli, Shigella spp, Citrobacter spp, Enterobacter spp, Proteus spp, Aeromonas spp, Klebsiella spp, Burkholderia spp, Vibrio spp, Pasteurella spp, Provedencia spp) were isolated and characterized. We also observed that out of 06 major filter plants of KW&SB, 03 filter plants were found highly contaminated. Preventive measures must be taken at all levels to prevent water contamination. Protection of water sources should be the first line of defense. Water treatment plants and water distribution systems must work in collaboration with each other to effectively implement quality standards for drinking water. All personnel responsible for monitoring the quality of water should be educated and provided in-service training on a regular basis.