Oxidizing iron filters use either air, potassium permanganate, chlorine or ozone to aid the filter media in oxidizing the iron. In some cases, there is already enough dissolved oxygen present so no additional oxidizers are needed.

Iron filters work by oxidizing (rusting) the iron and then filtering it out. We all know that simple iron or steel will rust in the presence of air and water. Rust is one type of oxidation. When water is underground in most wells, it is in a clear, also known as ‘ferrous’ or clear water iron. Iron filters take this clear iron and transform it to rust or ferric iron in the process known as oxidation. These trapped particles are periodically and automatically backwashed out to drain, usually once or twice a week. Iron filter systems also remove so-called red or red water iron, iron bacteria, manganese and in some cases hydrogen sulfide by oxidation and filtration.