Water is an important life source for all living organisms. Three fourth of the world is filled up of water. We, humans are using water for almost all the purpose and finally discharge the effluent to the water bodies. This polluted water is used by rural population for drinking and cooking purposes. In this study we have selected Dalvayi Lake on which four villages are dependent for drinking purpose. We have collected the water sample from different distance from the shore and also from different depths. Screening for pathogenic bacteria was done and various physical, morphological and biochemical tests were done to identify the organisms. Finally we came out with the result that the water is heavily contaminated with sewage water entering. Hence, the sewage treatment plant has to be upgraded timely and the treated water can be used for other agricultural purpose instead of letting it into the lake.