RO is very effective in reducing a range of home water contaminants. This is possible because the reverse osmosis membrane is comprised of microscopic pores which allow the pressurized water molecules, among the smallest molecules known to man, to pass through contaminants, and even dissolved ions are left behind. Additionally, RO systems always include a sediment pre-filter that traps fine suspended materials that permanently clog the membrane. Most RO systems also include a carbon pre-filter to remove chlorine, along with other contaminants that may damage RO membranes and affect that taste, color, and odor of the water.

Reverse osmosis is a low-energy process, useful for substantially reducing the complete dissolved mineral content of water. the process is practical in sizes ranging from a few gallons to million of gallons per day.

Anyone concerned about the quality of their home drinking water — particularly if they notice taste or odor problems or are aware of high levels of dissolves minerals in their water supply — should consider an RO system. Additionally, RO systems often are recommended for immune-comprised individuals who could be especially susceptible to infection from various waterborne contaminants. The Centers for Disease Control and Prevention (CDC) recommends reverse osmosis as a method for removal of a dangerous microorganism cyst called Cryptosporidium. Reverse osmosis systems, which generally include both and RO membrane and pre- and post-filters, offer a comprehensive means of eliminating more than 90 percent of potentially harmful contaminants in home drinking water.

A reverse osmosis system can treat for a variety of contaminants including:

Aluminum, Arsenic, Asbestos, Atrazine, Benzene, Chlorides, Chlorine, Copper, Cryptosporidium, Cyanide, Fluoride, Giardia, Lead, Mercury, Nitrates, Radium, Radon, Silver, Sodium, Sulfide, Trichloroethylene, and Total Trihalomethanes. NOTE: In California, State law requires that any reverse osmosis manufacturer or installer making specific health claims for a drinking water product must have that product tested and certified by a State approved lab.

There are many benefits to installing a reverse osmosis system beyond greatly reduced concentrations of contaminants. Cleaner, sparkling drinking water is probably the most noticeable. Because there is little to alter the RO-treated water’s natural state, the flavor of food can come though without any “chemical” taste. Brewed items such as coffee, tea, or soups may have a richer, more robust flavor, and fruit juices and powdered drinks mixed with RO-treated water may taste better, too. Even ice cubes can take on a crystal clear appearance.

Additionally, because of its low mineral content, using RO-purified water in household appliances such as steam irons and humidifiers can keep them working longer and more efficiently.

RO systems are capable of removing certain biological contaminants such as Cryptosporidium and Giardia. The pore size of the RO membrane along with the amount of pressure applied to the water will generally determine the rate of reduction of such contaminants. The Water Quality Association (WQA) cautions, however, that while RO membranes are reliable for treatment of a range of health contaminants, design considerations such as tiny seal leaks or manufacturing imperfections may prevent a unit from offering foolproof protection against biological contaminants for consumer drinking water systems. Therefore, WQA suggests that absolute disinfectant (a reduction of contaminants greater than 99.9 percent) be ensured with cyst-rated and certified products and post-disinfection systems such as ultraviolet light. NOTE: In California, State law requires that any reverse osmosis manufacturer or installer making specific health claims for a drinking water product must have that product tested and certified by a State approved lab.

The filters of your RO system should be changed periodically. In general, both the re- and post-filters should be replaces about every six months, or at least annually; however, the maintenance schedules may vary due to local water conditions, the quality of water being filtered, and the manufacturer’s recommendations. The reverse osmosis membrane normally lasts between 3 to 5 years. WQA suggests you closely follow the maintenance schedule provided by your water treatment specialist of the manufacturer to ensure that the system is in proper working order.

Most RO systems are compact units installed under your sink. (In some cases, they can also be installed on the countertop). A typical system is comprised of one or more pre-filters, a reverse osmosis module, a post-filter, and a pressurized holding tank (see diagram below). The pre-filters trap sediment, chlorine, and other contaminants before allowing water to pass into the reverse osmosis module. The RO module, containing the RO membrane, further isolates a range of contaminants before allowing treated water through the post-filter. The treated water received a final “polishing” as it flows through the post-filter and into a holding tank connected to a tap on the kitchen sink. The waste water rejected by the RO is sent down another line into the drain.

In order to select the product that best meets your needs, begin by having your water tested to determine its quality and which contaminants my be present.  If you are concerned about health-related contaminants, you local department of health can recommend state-certified laboratories to test you water.  If you are concerned about aesthetic contaminants (affecting the taste, smell or odor of your water), contact Joe Stern Water Conditioning for a FREE water analysis.