In this inoculation study, a number of effective factors in the growth of P.aeruginosa in drinking water were investigated. This study was conducted with the inoculation of the bacterium at the level of 104 /ml into drinking water and the factors investigated included: storage temperature of water (22 C° and 7C°), storage time of water (day zero, 3, 6, 12, 24, 48), type of mineral water (sterilized and non-sterilized) and tap water (sterilized and non-sterilized). The bacterium studied was P.aeruginosa. The main aim of this study was to reach a definite conclusion about the possibility of survival and growth of the bacterium in drinking water under the conditions mentioned. The different types of water were sampled and after preparing dilution, they were cultured in solid medium of BHI Agar and Cetrimid Agar and then they were incubated. In the end, storage temperature (22 C°) from the third day on, the sanitary condition of water (sterilized) from the 24th day on and the type of water source (mineral) on the 48th day had a positive effect on the growth of P.aeruginosa. Over all, temperature of water was the most effective factor in the growth and survival of P.aeruginosa as it had the highest growth at 22 C° water (P<0.01).