Microbial Study on Water Used for Dispensing

Microbial study on six kinds of waters used for dispensing was carried out by challenging five kinds of microbes to each water respectively. Waters used were fresh tap water, dechlorinated tamp water and fresh purified water with or without 0.05% ethyl p-hydroxybenzoate (paraben). And microbes were E. coli, S. aureus, P. aeruginosa, C. albicans and A. niger. Frerh tap water was found to be effective against, three microbes but only transiently effective against P. aeruginosa and none against A. niger.Additive effects of paraben to both fresh tap water and dechlorinated tap water were not observed, especially, antimicrobial activity, of fresh tap water against C. albicans was markedly reduced.On the other hand, additive effect of paraben was confirmed with fresh purified water and no chemical reaction, such as oxydation or ionic reaction due to free residual chlorine, was occurred. From our microbial study and chemical standpoint, fresh purified water and sterilized purified water were more suitable for dispensing use than fresh tap water.