Liquid filtration is the removal of solids from liquids by flowing the contaminated liquid through a filter medium that will retain the solid particulates and allow only clean liquid to pass through. A liquid filter is designed to remove impurities that occur in liquids, both from natural and unnatural sources. Liquid filters are used to clean or purify a product or extend the life of the piping by removing corrosive materials that induce erosion. Filters have also been used to remove bacteria from certain liquids to prevent spoiling and, in other cases, to remove harmful particles so that the liquid may be recycled and reused.