Analyses of drinking water taken from central and individual water supplies in Southern India (Idukki/Kerala) showed bacterial counts of 10(3)-10(6). E. coli were found in 11% and 28% of the samples. Aeromonads were identified more frequently than E. coli at 44% in central and 38% in individual water supplies. Due to this high rate of contamination, Aeromonas spp. must be considered as a possible cause of diarrhoea and other infections in this area.