Water filtration involves removing small particles like sediment, manganese, iron, chlorine and even gasses like hydrogen sulfide from the water. The filter traps these particles (in sizes as small as 10 microns), as water travels through it. Periodically the filter must be backwashed, so the unit has to be taken off-line. The flow of water through the filter is reversed, and the trapped sediment is rinsed out. When completed, the filter is ready to work again. To learn more about water filtration, check out the water FAQ.