Reverse Osmosis systems for home drinking water are units that consist of a combination of several filters. Depending on the system you chose, there is usually one or two prefilters that will filter out larger particles and chemicals from the incoming water. The water is then sent through the reverse osmosis filter to remove many other harmful contaminants. After the RO filter, the purified water is then stored in the pressurized holding tank.
Every R.O. system has at least one pre-filter (before the RO membrane) in the system - an activated carbon filter, which removes chlorine and other chemicals. This pre-filter helps to prevent fouling of the RO membrane filter. On some RO systems, there are sometimes two pre-carbon filters