The paper is connected with the ultrafiltration of well and surface waters using polymeric membranes made of polyacrylonitrile and polysulfone. The efficiency of the process was determined by measuring water flux, as well as bacteriological and physicochemical analysis of raw water and permeates. It was state, that the best well water flux was obtained for the membrane made of mixture polyacrylonitrile/polysulfone (by about 40% than membrane made of pure polymers). All investigated membranes totally remove iron, turbidity and bacteria E.coli, whereas organic compounds and mesophilic bacteria were also removed to a high degree.