How Does a Reverse-Osmosis Water Filter Work?

Purifying Technology

Reverse-osmosis filtration is a purification process in which pressurized water passes through a thin semi permeable membrane that strips out a wide array of contaminants and inorganic impurities.

Reverse-osmosis technology was initially used in the 1950s to separate salt from sea water, which is known as desalination. Bottled water companies rely on reverse-osmosis filtration to remove pollutants and microorganisms from their products. Reverse-osmosis water filters for the home and portable handheld units for hikers and hunters also have become increasingly popular in recent decades.

Key Features

Most reverse-osmosis water filters used in homes features several key pieces of equipment that typically are installed under the kitchen sink. These include:

* One or more pre-filters that strain out silt, sediments and other larger particles from tap water.
* A cellophane-like, reverse-osmosis membrane that screens out smaller contaminants and impurities down to .001 microns in size.
* A storage tank.
* A carbon filter that gives the water a final scrubbing before it comes out of the faucet.

For optimal results, the filters and membrane in a reverse-osmosis system must be replaced periodically.

Pros and Cons

A reverse-osmosis water filter will effectively purify drinking water be removing many unhealthy microorganisms and impurities such as arsenic, chlorine, copper, lead, nitrates and pesticides.

One disadvantage related to reverse-osmosis water filters is the cost, which averages about 5 to 7 cents per gallon of pure water. Another drawback involves wasted water. A reverse-osmosis filter typically uses four or more gallons of tap water to distill a gallon of pure water. Critics also have questioned whether reverse-osmosis filters can cause health problems by removing some of the beneficial minerals like calcium and magnesium that are ordinarily found in drinking water.

Resources

• What Does a Reverse Osmosis Filter System Do?