Effects of Monsoon on the Quality of Drinking Water Supplied to Karachi, Pakistan

To study the effects of monsoon on the quality of drinking water, supplied by Karachi Water and Sewerage Board (KWSB) to the city of Karachi, quality parameters of drinking water were analyzed before monsoon and after monsoon. A total of 13domestic water connections were selected as sampling points in Gulshan, North Karachi, Nazimabad, Gulberg, Liaquatabad, Landhi, Korangi, Shah Faisal, Jamshed, Saddar, Orangi, Baldia, Lyari and Keamari towns of Karachi. Samples were collected before monsoon (three times during June2020) and after monsoon (three times during Aug-Sept 2020) from each of the sampling point. Various quality parameters of the drinking water samples collected from selected locations such as pH, Total Dissolved Solids (TDS), Total Suspended Solids (TSS), Electrical Conductivity (EC), hardness, Ca2+, Mg2+, Na+, K+, Cl-, SO42- and NO3- were determined using standard methods. Detection of total possible microbial count was carried out for Total Coliform Count (TCC) and Total Fecal Coliform (TFC). The analysis shows that the physicochemical parameters for all the samples were found within the limits prescribed by WHO, except the values of EC, were found to be higher than the acceptable limit in the samples before monsoon. Whereas the entire drinking water samples tested after monsoon were found to contain TCC and TFC, making them not suitable for drinking. The major reasons of bacteriological contamination may be entering of waste water and the rain water through leakage of pipes during no flow situations. It is suggested to carry out strict monitoring of chlorination process of drinking water supply. To avoid microbial contamination, the underground pipelines of drinking water and sewer water should be distant. Overhead tanks in each town will help to maintain pressure in the drinking water pipelines.