To insure optimum efficiency, certain routine maintenance must be performed on reverse osmosis systems.
The standard reverse osmosis system consists of three stages, pre-filtering, the reverse osmosis process, and post-filtering.
Water flows from the water supply to the first stage, the pre-filter, where the 5-micron cartridge removes sand, silt, dirt, and other sediments that may be in the water supply. From there, the water flows to the reverse osmosis membrane cartridge.
Water is forced by pressure (at least 35 psi) through the semi permeable membrane. The good water passes through the membrane (at two drops per second) to the storage tank while the dissolved and particulate materials we don't want, are sent down the drain. We must always have a certain amount of water continually flushing across the face of the membrane to clean the porous surface and prevent plugging. The amount of good (product) water and the amount of flushing (reject) water is called the reject ratio. FOr residential R/O's this usually around 3:1. In other words, R/O's will require 4 gallons of water to make 1 gallon of purified water. That wastes a lot of water!
After leaving the storage tank but before going to the faucet product water goes through post filtering. The post filter or filters are usually of carbon type which will remove any remaining taste and odor.
Frequency of maintenance depends on a number of factors including condition of water and level of use.