Ultrafiltration is a physical membrane filtration technology, in which hydrostatic pressure forces a liquid against a semi-permeable membrane. The typical pore sizes of ultrafiltration membranes is between 0,01 microns and 0,1 microns. Suspended solids and bigger solutes are retained, while water and solutes smaller than the pore size of the membrane can pass through the membrane. Ultrafiltration technology reliable retains 99,9999% microorganisms, bacteria and viruses.

As a low pressure driven membrane technology it is extremely effective and has low energy consumption. Ultrafiltration is state of the art technology and used in municipal water treatment plants all over the world.