Three sewage waters with different sources of faecal pollution (human, pig and mixed origin) were analysed. Enumeration of Enterococci was performed and representative strains for each sample were isolated. Biochemical fingerprints of these strains were obtained by using a simple automated microplate system. The structure and composition of the Enterococci populations were studied and the most representative biochemical profiles were determined by cluster analysis. The diversity index was high for all the sewage waters sampled. The enterococcal populations detected in the three kinds of sewage waters were similar. Although many of the representative strains were found in the three kinds of samples, some strains were detected only in human sewage and others only in pig slurry.