UF can be used for removal of particulates and macromolecules from raw water, to produce potable water. It has been used to either replace existing secondary (coagulation, flocculation, sedimentation) and tertiary filtration (sand filtration and chlorination) systems employed in water-treatment plants or as standalone systems in isolated regions with growing populations. When treating water with high suspended solids, UF is often integrated into the process, using primary (screening, flotation and filtration) and some secondary treatments as pre-treatment stages.