Stage 1 (5 Micron sediment filter) Filter to extract suspended materials such as sediments, insects, asbestos fiber, rust, and particles down to 5 micron. Stage 2 (Granular activated carbon GAC filter) Filter to absorb heavy chlorine AND chlorine by-products such as chloramines, THM. Stage 3 Carbon block filter to remove any additional chlorine and organic matter from water without release of carbon fines.