Olansi RO Water Purifier employs an ionic composite filter with three layers that completes the filtration process in one composite filter. The result is that it's easier to change filters. The process of filtration involves passing water through three filters: a sediment filter pre-carbon filtration system, and an RO membrane filter. The sediment filter is used to remove large particles and impurities, while the pre-carbon filter eliminates the chlorine and bad tastes, and odor out of the water. In addition, the RO membrane filter gets rid of harmful substances such as arsenic and lead as well as other contaminants.