Previous studies have shown that many people are dying in developing countries because of using unsafe drinking water. This study has been carried out at the National university of Rwanda in order to assess the quality of drinking water provided to students in the university restaurant. The evaluation was carried out with Petri-film counts method.The quality of the restaurant water samples were compared with three industrial-bottled-water marks produced and marketed in Rwanda (Inyange, Huye, and Nil) and with the tape-water distributed by EWSA. The microbiological results show that 3 out of 5 samples collected in the restaurant were contaminated with fecal colonies, giving a mean bacterial contamination of 4180 colonies/100ml, while the samples from EWSA, Inyange, Huye and Nil industries complied with US.EPA standards. The Petri-film counts result was confirmed by the standard plate-culture methods. The Petri-film counts method is thus sensitive enough to quickly help monitor the quality of drinking water. The Petri-films are also accurate to monitor the quality of milk and juice.