Our work aims to study the impact of the quality of water for drinking and cleaning the milking room on the physicochemical and bacteriological quality of milk. To do this, we collected milk and water samples from six farms in northern Tunisia. It emerges from this study that the results of physico-chemical analysis of milk are generally included in intervals close to the standards adopted for milk but the majority of milk samples collected can be described as poor hygienic quality. The quality of the cleaning water in the milking parlour, according to the statistical results, affects the total aerobic mesophilic flora as well as the total coliforms in milk. The quality of the water used for watering, according to the statistical analysis, affects the fat content of the milk. It is clear that water quality is not the only factor affecting milk quality.