UF is also one membrane technology to remove viruses completely. The pores of UF membranes can remove particles of 0.001~0.1μm from fluids. Both micro filtration and ultra filtration can also be applied for pre-treatment of water for Reverse Osmosis.

Ultrafiltration (UF) is a pressure-driven technology commonly used to remove suspended solids, bacteria, and viruses, providing a physical barrier to pathogens in potable water production. In addition to providing a very high purity, low Silt Density Index (SDI) product, regardless of the incoming water quality, UF offers a pretreatment alternative for surface water, seawater, and biologically treated municipal effluent prior to reverse osmosis (RO) and other membrane systems such as electrodialysis reversal (EDR) with a small footprint and low chemical consumption relative to conventional pretreatment, and high-quality pretreatment to other processes.