The aim of this study was to evaluate the microbiological quality of different commercial mineral water brands, wells and reservoir supplies in surrounding areas of the city of Marília, Brazil, to determine the amount of total and fecal coliforms. Eighteen samples of each source (mineral and reservoir supplies) were analyzed using Colilert Technique in cellophane. The results revealed that one sample of mineral water and one sample collected from the reservoir supply had been contaminated by a bacterium of the total coliform group, and there were found one bacterium/100 ml of water. None of the water samples showed contamination by fecal coliforms.