Incoming raw water passes through a compressed pocket of air contained in the first tank. The air precipitates the iron into solid form and is removed when it passes through the filters media bed contained in the second tank. The media acts as a catalyst in the reaction between iron and oxygen that also causes the iron to precipitate into a solid.
As more water passes through the unit the air becomes depleted and the media becomes overloaded with the iron. Periodic automatic regeneration replenishes the supply of air and cleans the media of filtered iron.