Anionactive detergents occurring in water in concentrations up to 100 micrograms . ml-1 do not exert inhibitory effects on the present microflora, either in case of heterotrophic bacteria, indicators of fecal pollution, or pathogenic and facultative pathogenic bacteria, including viruses. On the contrary, the studied bacterial species are able to decompose surfactants and utilize them as carbon source. Though, the rate of degradation is different with respect to respective substances, as well as with regard to the species of organisms, and their physiological activity. Only at higher detergent concentrations inhibition of microbial cell growth may be observed.