Plumbing - Under Sink Water Purifiers

Most homeowners have experienced the following unfortunate scenario: You enter the kitchen or bath, turn on the faucet and out comes water filled with sediment or minerals. You can see the build-up over time on the water cup or toothbrush holder. Sometimes unseen chlorine and other distasteful chemicals are the culprit.

Under-the-sink water purifiers to the rescue!

For a modest cost of about $50, you could have clean water instantly in the kitchen or bath. Installation is no more difficult than putting in a garbage disposal. The savings in not buying so much bottled water will quickly erase the cost.

For most models, the installation is pretty much the same.

Just disconnect the cold-water supply line underneath the sink. Be careful to use only the cold water line. Filters are not designed to work correctly with hot water.

Sometimes it's attached with screw-tightening clamps similar to car water hoses. Sometimes, it's a squeeze clamp that will require strong fingers or a good pair of pliers.

But that's usually the easy part. If the hose has been attached for a long time, it will probably stick. Take care not just to jerk hard. You'll split the hose off, requiring a lengthy and difficult removal of the remainder with a knife. Or, worse, you'll bust off the nib the hose attaches to. Twist and pull moderately, and if necessary squirt something in the hose lip that will dissolve calcium carbonate and/or aluminum or copper oxide.

Clean off all the fittings really well. Sometimes ordinary cleaning solvent is enough. Other installations will require a little bit of gentle sanding. A clean surface is key to a dripless finish.

Now wind ample Teflon plumber's tape around the nib. Never secure a hose with PVC glue or other adhesive. Someday you'll have to replace the hose and it will be nearly impossible to get off without damaging the pipe. In any case, it would make the job ten times harder and longer.

Now for the filter.

The water filter fits between the cold-water supply and the faucet. Filters often use some kind of activated charcoal, a type of carbon that grabs the minerals, chlorine and other molecules on the way to the spigot. They sit inside a canister that opens up or pulls down so the filter can be changed every six months to a year. So, make sure to face the cannister in a way that doesn't prevent that.

Flexible hose attaches to the cannister/filter housing and then onto the nib where the previous line was removed. They're typically included with the water filter kit. Make sure not to kink them or even have too sharp a bend. That leads to blockage or cracking over time. Trim off the ends of the hose to prevent that.

Most hoses can be attached with simple compression fittings that also come with the standard kit. Hand tightening is often good enough. Make sure you don't over-tighten them. That leads to cracked hoses near the fitting.

Cannisters are attached in a number of different ways. Sometimes a small ring attaches to the U-shaped pipe under the sink. Others are designed to attach to the wall with a mounting bracket. Just follow the instructions. Take care, though, when mounting on the wall to drive into a stud or to use good dry-wall screw holders. Cannisters full of water can weigh several pounds.