This study was conducted to determine of microbiological quality of drinking and usage waters obtained from different sources in Bursa province and its districts. For this purpose, a total of 200 samples including 119 tap and 81 artesian well waters were collected. The samples were investigated for the presence of coliform, E. coli, enterococci, S. aureus and Salmonella bacteria by membrane filtration method. Coliform, E. coli, enterococci contamination rates were found as 72.8% (59/81), 48.1% (39/81) and 40.7% (33/81) respectively, in the artesian well water samples. In the tap water samples, E. coli and enterococci contamination were determined as 2.5% (3/119) and coliform as 12.6% (15/119). Pathogen staphylococci (coagulase-positive S. aureus) were detected only in one artesian well water sample. On the other hand, Salmonella was not isolated from any water samples. It was determined that 37.5% (75 samples) of the analyzed samples did not comply with water guidelines criteria which were published by the Turkey Ministry of Health. Also the higher contamination rates were observed in artesian well water samples compared with the tap water. The results of the current study showed the presence of fecal indicator bacteria in water samples, and that these waters if consumed may constitute potential health risks in immune-compromised, ill, old people and children.