Whole-house filtration, faucet filtration, aquarium filtration, and restaurant filtration are all applications for RO systems. Whatever type of water you start with, a RO system will almost certainly meet your requirements. It filters out 98 percent of dissolved particles, making it safer to consume.A prefilter absorbs sediment and chlorine in water before forcing it through a semipermeable sieve to remove dissolved particles in a reverse osmosis system. Water goes through a postfilter after leaving the RO membrane to polish the drinking water before entering a designated faucet. The quantity of pre filters and postfilters in a reverse osmosis system determines the stage.