Ordinary water filters use screen only particles of dirt sediment from water. Reverse osmosis employs a semi-permeable membrane that removes not only particles but also an extremely high percentage of dissolved contaminants-molecule by molecule from raw tap water. Ordinary filters remove only insoluble impurities also removes soluble impurities like salts, hardness a heavy metals.
The membrane consists of several thin layers or sheets of film that are bonded together and rolled in a spiral configuration around a plastic tube. (This is also known as a thin film composite or TFC membrane) The material of the membrane is semi-permeable with .0001 micron pores. It allows water molecules pass through while acting as a barrier to dissolved solids (i.e.: mineral chemical contaminants). When the feed water stream passes across the surface of the membrane, the molecules penetrate the membrane surface, working their way around the spiral and collecting in the center tube. The remaining contaminants are concentrated and washed from the surface of the membrane down the drain.
The raw tap water first flows through a 5 micron particle FILTER  to remove dirt, rust and other sediment. The water then flows into a carbon briquette cartridge FILTER  which takes out 98% of the chlorine and organic chemicals. The next stage of the process is FILTER  the Block carbon filter to filter multi-chemical compounds and suspension.  The reverse osmosis membrane (TFC) which will separate 95-99% of the dissolved contaminants from the water molecules. The contaminants are then washed down the drain. The next stage of the RO series process is the small CARBON FILTER removes the remaining traces of chemicals, tastes and odors. The R.O. water is stored in a 17 Litre TANK. Inside the tank is a balloon-like rubber diaphragm, pre-changed with 14 psi of air. As the tank fills, the air pressure increases and pushes the water out when the faucet is opened.
Although the idea of reversing osmosis has been known for every 10 years, the practical application is a recent development. In 1962 the U.S Government funded the first R.O. plant which processed 1000 gallons clean water per day. Today, there are more than 3000 large R.O. treatment plants, each producing more than a million gallons of drinking water each day. In 1991, the U.S. Army bought 8,000 large membranes to their mobile water purification units for troops in Desert Storm. In 1993, the U.S. Government bought another 6,300 large membranes to purify flood water in the Midwest.
Depending upon the model you choose the RO water makers can be installed on wall i.e. wall mounted and also under the counter.
Under ideal conditions, the membrane is rated at 15 litres per hour of water production. This is a lot of water for the average household's drinking and cooking requirements.
The RO System (excluding filters) is guaranteed for 1 year for material and workmanship. All defective parts will be replaced free within the first year. The membrane has a one year pro-rated guarantee.