If you get your drinking water from a municipal source, like the local city water treatment plant, it will have been treated to meet certain U.S. Environmental Protection Agency (EPA) standards. Just because your water meets these standards, however, doesn’t mean it’s free from every contaminant or additive. And, if you get your water from a private well, it’s especially important for your water to be tested and treated for anything that might have contaminated the water supply. Once you’ve had a complete water test performed on your water, you can choose the best drinking water filter system for your specific problems.
At the municipal level, water is treated to remove most sediment, chlorinated (or treated with another disinfectant like chloramine) to kill microorganisms, and filtered to remove dissolved particles and many chemicals. The EPA sets limits on more than 90 different contaminants and water treatment plants may employ additional treatment methods as required. Most water systems in the U.S. also add fluoride to the water to help reduce tooth decay. Once the water leaves the plant and goes into your home, it can still contain low levels of a number of contaminants, as well as chlorine or chloramines and fluoride.
As a rule of thumb, RO systems have three, four or five-filter stages. Without detailing each stage of the RO process (since the number of stages varies based on the model), we outline here some basic maintenance information that applies to most RO units.
First: In order to protect the delicate RO membranes, water first flows through a pre-filter. This pre-filter cartridge is designed to filter out dirt, silt, sand and other sediments. This pre-filter should be changed every 6-9 months. If not properly maintained or changed on schedule, the pre-filter can foul or become clogged, thereby making it unable to protect the RO membranes.
Second: The next phase is generally a carbon filter which is designed to remove chlorine and other taste or odor contaminants. This is important because chlorine can ruin the RO membrane. This carbon filter should be replaced every 6-9 months, also.
Third: This is the actual reverse osmosis phase. Reverse osmosis (RO) is a separation process that uses pressure to force water through a membrane. The membrane retains the contaminant on one side and allows the pure solvent (water) to pass through to the other side.
This process is the reverse of the normal ‘osmosis process’, which is the natural movement of solvent from an area of low solute concentration, through a membrane, to an area of high solute concentration when no external pressure is applied.
Water passes through the RO membrane at generally 35 pounds per square inch (psi). At this rate, roughly two drops per second. The contaminants rejected by the membrane are piped down the drain. RO membranes should be replaced every 2-3 years.
NOTE: The filter and membrane lifespan will vary based upon local water conditions and household usage.
Fourth: Finally, a carbon filter stage is usually added to “polish” off the water at the end of the cycle. This stage removes any remaining taste or odors to create outstanding drinking water. The carbon filter should be changed every 6-9 months.
No, a softener and an RO system are actually a great combination. The softener will soften the water throughout the home, AND the RO system will remove 98% of all sodium in the water. This duo makes for great-tasting drinking water.
Because of calcium and magnesium, the minerals that make water hard, are difficult minerals for an RO membrane to remove, the softener acts as a protective barrier for the RO system. This protection keeps the RO system from fouling and can extend the life of the membrane