What is reverse osmosis?

Reverse osmosis is a water purification method that uses a membrane filtration technology that works by forcing water under pressure through the very tiny pores of a semi-permeable membrane. Combined with carbon, sediment and mechanical filtration to produce highly purified, great-tasting water.

How does it work?

Water, driven by normal city water pressure, flows first through a carbon pre-filter, which removes organic contaminants including chlorine and its by-products. Next, it enters the reverse osmosis membrane, a very tight, sheet-like filter, that allows water to pass but rejects dissolved solids like sodium and impurities like lead and arsenic. Some of the water entering the unit is used to cleanse the membrane surface and flows to the drain pipes. The purified water is stored in a small storage tank until it is needed. When the faucet mounted on the sink is opened, the purified water is forced by air pressure through another carbon filter, which gives it a final filtration and from there to the faucet. (This is a simplified description of a three-stage RO unit).

Is distilled water purer than reverse osmosis water?

Distillers typically remove a few parts per million more of common mineral constituents like sodium. However, distillers don’t do a good job with volatile chemicals with a low boiling point. Chloramines, for example, which many cities now use instead of chlorine as a disinfectant, aren't removed well by distillers. Reverse osmosis, with the carbon filters that accompany it, does a very good job with chloramines. Unless volatile chemicals like chlorine are removed by carbon filtration before they enter the distiller, they will be released into the room air or they will end up in the distilled water. But in general, distilled water is very pure, as is reverse osmosis water.

How much does it cost to service a reverse osmosis unit ?

Starting as low as $34.99 per year, a standard two-stage reverse osmosis filter system can last up to 12 months depending on water consumption and condition. Reverse osmosis membranes are guaranteed for one year, although they commonly last up to five. The price of a standard membrane starts at just $99.99.