They are used to remove fine and colloidal impurities, organic substances, bacteria and viruses from water, without changing its salt composition. The ultrafiltration method, based on the use of membranes with a pore size of 0.1 to 0.01 microns, is designed to obtain drinking water, process water, and can also be used as a purification degree before softening, desalting, nanofiltration and reverse osmosis plants.