Between 1985 and 1986 2064 samples of raw-, drinking- and swimming-pool-waters from Southwest-Germany have been examined according to German Drinking-Water Standards as well as for the occurrence of Enterobacteria, fecal streptococci and Pseudomonas aeruginosa. With the exception of Pseudomonas aeruginosa all parameters showed a statistically verified dependence on each others occurrence, which was most significant between the two criteria "Escherichia coli" and "fecal streptococci". The results of the investigation increased the doubts concerning the value of "coliforms" as a quality criterion. Enterobacteria seem to be a suitable quality criterion for waters which have received a disinfecting treatment.