ABSTRACT
Water used in the pharmaceutical industry should have special physicochemical and microbiological characteristics. One of the quality items of pharmaceutical water is level of microbial content. For this reason selection of effective disinfection method is the main item for design of pharmaceutical water systems. Water systems can be maintained at temperature below 10 [degree sign]C and more than 70 [degree sign]C but maintaining of water at ambient temperature could increase of microbial content. In this condition use of disinfectant is useful for reducing of microbial content. Some of them such as chloride, ozone and hydrogen peroxide due to good results have more application. In this study, effect of three disinfectants chloride, ozone and hydrogen peroxide with 1 ppm concentration, consider on five microorganisms. Pseudomonas aeruginosa, Staphylococcus aureus, candida albicans, Aspergillus niger and E.coli. Counting and decreasing of microorganisms showed the efficiency of disinfectants. Finally ozone was selected as the best disinfectant due to high efficiency