Among all the technologies of water treatment, membrane technology, appears to be the most promising. The major advantage of this technology is its ability to produce water with a constant and well adjusted quality. Moreover, membranes remove a wide range of substances, ranging from particles to ions, including bacteria and viruses, and they can operate without any chemical addition to raw water. The paper discusses the results of investigations concerning the application of ceramic and capillary microfiltration and ultrafiltration membranes for the purpose of treatment of natural water. The effectiveness of ultra- and microfiltration was assessed by volumetric measurements of the permeate :flux as well as by microbiological and physico-chemical analyses.