In 2010, three thousand one hundred and thirty two water samples were collected from different areas of Lahore (Pakistan).These samples were analyzed in WASA Laboratory to know about quality of drinking water. About 94% samples were found safe for drinking purpose and 6% samples were bacterially contaminated. Under follow up sampling programme, sampling was done from locations where water samples were found bacterial contaminated. In 2010 74% water samples were collected under routine sampling, 18% samples were collected against complaint received about quality of drinking water from different areas and samples were collected under complaint sampling programme. 8% samples were collected under follow up sampling. Two types of contaminations were observed. 1. Physical appearance of water samples. 2. Bacterial contamination 0.5% samples were found unsafe on the basis of physical tests reports and 5.7% on bacterial tests report. To remove contamination flushing of pipelines and chlorination was done by operation staff on instruction of WASA lab.