4-Stage Reverse Osmosis System and 5-Stage Reverse Osmosis

Reverse osmosis systems offer a more advanced treatment process than carbon filtration only or entry-level pour-through pitchers. At the heart of the system is a reverse osmosis membrane that removes impurities as small as an atom. Drinking water passes through a series of sediment and carbon RO filters before and after the RO membrane to eliminate any unwanted tastes and odors and provide fresh water. 
4-Stage Reverse Osmosis System
1. Sediment prefilter: A sediment prefilter screens out dirt, sand, rust, and other microscopic particles 15 times smaller than a grain of sand.
2. Carbon prefilter: An activated carbon prefilter reduces elements that cause water to taste and smell unpleasant, including chlorine. 
3. RO membrane: The RO membrane filters out dissolved substances, including radium, lead, arsenic, and many others.
4. Polishing filter: The polishing filter is a second activated carbon filter that polishes the water to make sure it's crystal clear.
5-Stage Reverse Osmosis System
1. Sediment prefilter: A sediment prefilter screens out dirt, sand, rust and other microscopic particles 15 times smaller than a grain of sand.
2. Carbon prefilter: An activated carbon prefilter reduces elements that cause water to taste and smell unpleasant, including chlorine.
3. 2nd carbon prefilter: Another activated carbon prefilter reduces elements that cause water to taste and smell unpleasant, including the taste and odor of chlorine.
4. RO membrane: The reverse osmosis membrane filters out dissolved solids, including radium, lead, arsenic, and many others.
5. Polishing filter: The polishing filter is a second activated carbon filter that polishes the water to make sure it's crystal clear.