Reverse Osmosis Theory of Operation

Reverse Osmosis

A high quality R.O. membrane is "semi-permeable," which means that it allows water to pass through but prevents dissolved particles from passing through. If you place a membrane between two compartments as in the container shown below, and then place salt water in one half of the container and pure water in the other half, a fundamental scientific principle comes into play. That is, two different concentrations of liquids within the same system will try to reach equilibrium (i.e. the same concentration of contaminants) on both sides of the membrane. Of course the only way for this to happen is for pure water to pass through the membrane to the salt water side in an attempt to dilute the salt solution. This attempt to reach equilibrium is called OSMOSIS.

Reverse Osmosis is the reversal of the natural flow of osmosis. In a water purification system, the goal is not to dilute the salt solution, but to separate the pure water from the salt and other contaminants. When the natural osmotic flow is reversed, water from the salt solution is forced through the membrane in the opposite direction by application of pressure - thus the term REVERSE OSMOSIS. Through this process, we are able to produce pure water by screening out the salts and other contaminants.

Process of a Reverse Osmosis System

With our UnderSink RO System, the raw tap water first flows through a 5 micron SEDIMENT FILTER to remove dirt, rust and other sediment. The water then flows into a 10 micron CARBON FILTER which takes out 98% of the chlorine and organic chemicals. The water proceeds to the Automatic Shut-off (ASO). If the tank is full, all the inlet water stops there. If the tank is less than full, the water continues. The next stage of the process is the reverse osmosis membrane which will separate 70-99% of the dissolved contaminants from the water molecules. The contaminants are then washed down the drain.

The next stage of the process is the small carbon POST FILTER that removes the remaining traces of chemicals, tastes and odors. The R.O. water is stored in a 3 gal. TANK. Inside the tank is a balloon-like rubber diaphragm, pre-charged with 7 psi of air. As the tank fills, the air pressure increases and pressurizes the water so that it flows to the FAUCET without a pump. The faucet is installed on the kitchen counter or the sink. It is a dual action faucet offering intermittent flow (to fill a glass, hold the handle down) or continuous flow (to fill a coffee pot, lift the handle up).