In the Gdańsk region urban development and intensive take off have caused an increase in water exploitation. As a consequence of the changes of hydrogeological conditions, a deterioration of chemical and bacteriological quality of water has been observed. Routine bacteriological quality control does not include some specific bacteria which are characteristic for the groundwater environment and can have negative influence on the physical and chemical properties of water. Among such bacteria there are sulphate-reducing bacteria (SRB). In the paper frequency of SRB occurrence in raw water from Cretaceous and Quaternary formations and in treated water has been described. It has been proved that bacterial consortium isolated from groundwater show preference to sodium lactate as a main source of carbon and energy. SRB have a negative influence on organoleptic properties of water quality and the technical condition of distribution net, the water should be disinfected. It has been proved that non-reagent methods, like UV radiation and microfiltration, are effective for SRB elimination from groundwater.