Question: What are the Basis Components of a Reverse Osmosis System?

Answer:

1. Cold Water Line Saddle Valve: Saddle Valve that fits onto the cold water supply line. The saddle valve has a piercing needle that penetrates into the cold water line to supply the water for the RO system.

2. Pre-Filter (s): Water from the cold water supply line enters the RO pre filters first. There are two or three pre-filters used in a reverse osmosis system. The first pre-filter used will be a sediment filter. This filter is used to remove sand, silt, dirt and other sediment. Next is a carbon block filter which is used to remove chlorine and chemicals from the incoming water. When a RO system has 3 pre-filters, the third filter will also be a carbon block filter.

3. Reverse Osmosis Membrane: The reverse osmosis membrane is the heart of the system. The most commonly used is a spiral wound TFC membrane (thin film composite/material). CTA (cellulose tri-acetate) can be used when carbon block pre-filters are not required, however this type of membrane is not very popular in today’s environment.

4. Post filter (s): After the water leaves the RO storage tank, but before going to the RO faucet, the product water goes through the post filter (s). The post filter is carbon (either in granular or carbon block form). Any remaining tastes and odors are removed from the product water by post filtration.

5. Automatic Shut Off Valve (ASO): To conserve water, the RO system has an automatic shutoff valve. When the storage tank is full (this will vary based upon the incoming water pressure) this valve stops any further water from entering the membrane, thereby stopping water production. By shutting off the flow this valve also stops water from flowing to the drain. Once water is drawn from the RO drinking water faucet, the pressure in the tank drops and the shut off valves opens, allowing water to flow to the membrane and waste-water (water containing the contaminants) to flow down the drain.

6. Check Valve: A check valve is located in the outlet end of the RO membrane housing. The check valve prevents the backward flow of product water from the RO storage tank. A backward flow could rupture the RO membrane and of course it will empty the storage tank.

7. Flow Restrictor: Water flow through the RO membrane is regulated by a flow control. There are many different styles of flow controls. This device maintains the flow rate required to obtain the highest quality drinking water (based on the gallons per day capacity of the membrane). It also helps maintain pressure on the inlet side of the membrane. Without the flow control very little drinking water would be produced because all the incoming tap water would take the path of least resistance and simply flow down the drain line. The flow control (restrictor) is located in the elbow fitting on the membrane housing where the RO drain line tubing is attached.

8. Storage Tank: The standard RO storage tank holds up to 4.5 gallons of water. A bladder inside the tank keeps water pressurized in the tank for dispensing to your faucet and/or refrigerator ice maker.

9. Faucet: The RO unit uses its own faucet, which is usually installed on the kitchen sink. Be certain you install the faucet where it will not interfere with other sink faucets and the outlet of the neck of the RO faucet is over the sink.

10. Drain line: This line runs from the outlet end of the reverse osmosis membrane housing to the drain. This line is used to dispose of the impurities and contaminants found in the incoming water source (tap water).