Chlorination is a low cost and very effective method to eliminate odors, stains, kill bacteria and pre-treat water prior to iron filters. A small amount of chlorine is injected as the water flows into the contact tank, giving time for the chlorine to work properly. The Pro-OX iron filter works better with the chlorinated water. It removes iron, manganese, & odors. Then water flows thru the Carbon Backwash Filter and into the home. The result is clean, odor-free, chlorine-free water.