Drinking water chlorination is affected by many factors including chlorine dose, pH, temperature and contact time. Diminutive work has been reported regarding the bacterial pollution of drinking water in Pakistan. In addition, no proper conditions have been reported for effective chlorination system to meet WHO and EPA drinking water quality standards. This book presents the study designed to optimize the required conditions for chlorination for maximum inactivation of E. coli and Salmonella in distilled, tap and well water. Three different dosages; 0.25,0.5 and 1.0 mg/L were applied. Samples were collected at 0.5, 1, 3, 5, 10, 15, 30 and 45 minutes to determine the microbial percent survival at pH 6,7 and 8 and 15, 25 and 35 ?C temperatures. The study will be informative for optimizing disinfection conditions for given water. It will also be supportive for researchers and policy makers in their way to provide safe drinking water to country mates.