MICROBIOLOGICAL QUALITY OF DRINKING-WATER IN SOUTH-WESTERN GREECE

A study was carried out in order to estimate the presence of enteric a nd non-enteric indicators in the water distribution systems of Western Greece and to evaluate different methods for culture and isolation of coliforms in that region, under several incubation conditions and usi ng different media. According to the different media and techniques us ed, the numbers of water samples found unsafe for consumption represen ted 21, 17 and 10% of the total, when mT7 agar, M-Endo agar LES (Membr ane Filtration technique) and Most Probable Number (MPN) techniques we re used, respectively. In one third of the samples oxidase positive mi croorganisms were present, which were almost eliminated by using anaer obic incubation of the media. Faecal streptococci were found only in 5 % of the samples tested. The MPN technique proved to be significantly less efficient in recovering the coliform colonies than the Membrane F iltration (MF) technique (x(2) = 125.758 < 182.405). The use of m-Endo agar LES and mT7 agar showed no statistically significant difference in detecting total coliforms (x(2) = 162.55 > 162.422). However, a lar ger mean number of colonies per sample developed on mT7 agar, indicati ng that the latter medium should be used in our region for the detecti on of total coliforms.