How Does Reverse Osmosis Work?

Reverse osmosis systems purify water by forcing pressurized water through a very fine, plastic membrane.

Stages of reverse osmosis:

• During the initial filtration stage, tap water or well water (pressurized by a booster pump) is passed through a particle filter (a pre-filter) that removes silt, sediment, sand, and clay particles that might clog the R/O membrane.
• The water is then forced through an activated carbon filter that traps minerals and contaminants such as chromium, mercury, copper, chloramine and pesticides. It also removes chlorine, which is important, as chlorine will shorten the life of the membrane.
• Water is transferred under pressure into the R/O module, allowing only clean water to pass through the small pores in the membrane. Impurities unable to pass through the membrane are left behind and flushed down the drain.
• Treated water is then sent to a storage-tank. Treated water is passed through an activated carbon filter before use to further improve the water's taste and smell.

What Are the Benefits of Reverse Osmosis?

Reverse osmosis can remove dissolved solids, salts, minerals that cause hardness, organic chemicals and other impurities. It can improve the taste of water for people who do not like the taste of dissolved mineral solids. Treated water will not produce scale in kettles and coffee makers. Because sodium and potassium are removed, people on a medically prescribed sodium- or potassium-restricted diet may benefit. R/O units also remove contaminants such as chromium, mercury and nitrates. In addition, reverse osmosis removes fluoride.

Is Reverse Osmosis - Treated Water Safe to Drink?

Reverse osmosis treatment systems remove minerals like calcium and magnesium from drinking water. In Canada, water is a minor source of such minerals when compared to foods. If you consume a reasonably balanced diet, you do not need to take a mineral supplement when drinking water treated with a reverse osmosis system.

Additional Information

Reverse osmosis is a scientific application where dissolved contaminants in water are physically removed by passing it under pressure through a special membrane. The process is similar to the way your body’s cells absorb water. Reverse osmosis will remove up to 98% of dissolved contaminants such as minerals, salts, metals and organic matter that may be present in a water supply. Pores in the reverse osmosis membrane are so small that only water molecules can make it through and the contaminants that are not recognized by the membrane are rejected and flushed down the drain. By way of example the pores of the reverse osmosis membrane are 0.0006 microns. A common bacteria is from 0.4 – 1.0 microns, a virus is from 0.2 – 0.4 microns and dissolved sugar is 0.001 – 0.005 microns. So it’s easy to understand why they just don’t make the passing grade.

The following shows the rejection rate of only a few of the commonly found dissolved solids in drinking water.

Information obtained from (CMHC) Canada Housing and Mortgage Corporation and Health Canada and other industry sources.