Some studies on the bacteriology of drinking water in Rawalpindi/Islamabad region

Abstract

The following survey was conducted to study the prevalence of Enterobacteriace in Government supplied drinking water provided to Hospitals in the areas of Islamabad and . Rawalpindi. Fifty water samples were taken from 25 Hospitals over a period of 6 Months, from April to July 2000. Analysis was done by physical, chemical and bacteriological testing of the water. Contamination levels were determined by using MPN technique. Escherichia coli was the indicator organism for contamination. Fecal contamination was also determined by incubating the test samples in a water bath at 44° C for 24 hours. First sampling was conducted from April to May 2000 and repeat sampling was done from June to July 2000. During first sampling the mean temperature was 19° C and during second sampling it rose by two degrees to a mean temperature of 21 ° C. the pH varied by only two pOints; at first sampling it was pH 7.1 and at second sampling it was 7.3. Residual chlorine was detected in four samples during the first two months and only one sample during the second two months. MPN values were seen to rise over the sampling period corresponding to a rise in temperature and pH. Bacteriological analysis and identification was performed. Escherichia coli, Salmonella typhimurium and Klebsiella pneumonia were identified. Escherichia coli was present in 66 % of the samples tested, Salmonella typhi in 41 % and Klebsiella pheumoniae in 21 %. The roost contaminated water was from Rawal Dam, being supplied to Rawalpindi. Seven treatment techniques were applied to determine which improved the potabliltystandards the most. It was seen the boiling was the best method, which completely disinfected the water by just a three minute boil, after which came chlorination, filteration, bleach, iodination, commercial silver drops and finally sunlight.