How To Install An Under Sink
Residential Reverse Osmosis Water System

Of the various ways you can filter home's drinking water, a reverse osmosis system offers one of the better solutions. In this system, a semipermeable membrane removes ions, molecules, and larger particles from drinking water. Reverse osmosis offers several advantages over different types of filtration since it offers 4 or 5 different stages of filtration and removes most harmful contaminants—even heavy metals such as lead. There are very few parts to a reverse osmosis system, making it very easy to clean and maintain. And it is fully approved by the EPA. 

 

When compared to the other point-of-use filtration systems, reverse osmosis tends to be more effective than simpler carbon black (charcoal) filtration systems, and considerably less expensive than ultraviolet disinfectant systems, which are the very best at killing pathogens. Where water supplies are adequately treated with chlorine, a reverse osmosis system is the best choice. 

 

While there are reverse osmosis systems that can be installed to treat all the water in the home, it is more typical for an under-counter unit to be installed beneath the kitchen sink where most of the water used for drinking and cooking is provided. The unit includes four or five separate filtration canisters, each of which filters a different group of contaminants, plus a storage tank that holds the purified water. A countertop spigot, separate from the house faucet, delivers the purified water when needed. 

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Although the physics of how reserve osmosis filtration works are complicated, installation is fairly straightforward. 

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Before purchasing a reverse osmosis system, make sure there is enough space under the kitchen sink for the RO tank and filter system. Take measurements of the available space. In a sink space filled with a garbage disposer or other items, an RO unit with its tank and multiple filters may be hard to fit. 

 

Also, make sure you have an idea of what cold water source can be used. Most units come with a tee connection that taps into the 1/2-inch cold water supply line going to the faucet. In some cases, there is a 3/8-inch flex line that comes down from the faucet. In that case, an adapter tee above the shut-off valve can be used to provide a source of water for the filter system.