Installing an Under-Sink Water Filter

Under-Sink Water Filters

The steps shown below show installing a simple single-stage filtration and absorption system, which will filter out most particles. It has a single small filter that takes up little space and needs to be replaced only twice a year or so. Two- and three-stage filters have, unsurprisingly, two or three canisters. Some filter systems add a tank as well. Here are some common filter options:

• Activated carbon (sometimes called charcoal) filters are inexpensive. They will remove most particles and much of the chlorine, but cannot remove heavy metals like lead and copper and won’t improve acidic water from wells. Over time, as particles collect, water pressure through the faucet will lessen as particles collect and clog.
• KDF (kinetic degradation fluxion) filters cost more, but do a better job of removing (actually, converting) chlorine and will effectively filter out heavy metals. They also kill microorganisms that are often missed by an activated carbon filter.
• An ion exchange filter is typically a canister (it may be one of the stages of a two- or three-stage filter system) containing tiny resin beads that “deionize” water, to remove nearly all inorganic particles. When used along with an activated carbon or KDF filter, pretty much all inorganic matter, parasites (including giardia), and chlorine will be removed.
• If you have serious water problems, the most common solution is a reverse-osmosis filter (see photo). These typically have two or three canisters plus a tank, and so take up a good deal of under-sink space. In addition to the filtering power of KDF filters, a reverse-osmosis filter removes radioactive contamination, which is a problem in many areas, and turns hard water into soft, drinkable water.