How to Install a Filter on Your Kitchen Sink

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Have you ever considered installing a water filter on your kitchen sink so that you can pour a fresh glass of water right from your kitchen sink faucet instead of constantly buying purified water or boiling water in order to cleanse it before consumption? Sure, there are pitchers that come with water filters, but those can only purify so much water at a time, and what happens when you need a cool glass of water but you go to pour some from the pitcher in the fridge and realize that the last person left it completely empty without refilling it? It may seem like a daunting task, but we promise you that once the filter has been installed, it will ultimately save you more time and energy than you currently realize.

Step One: Shut off the main water valve
To begin, you’ll want to make sure that the main valve for the cold water supply to the kitchen is shut off. You can usually find the shutoff valve in the basement, crawl space, or utility closet. If you can’t shut off only the kitchen’s water supply, then you’ll need to make sure that your home’s entire water supply is shut off for the time you’re working on installing the water filter. Make sure to let out any water trapped in the pipe between the sink before you begin.

Step Two: Cut into the water-supply line
Make sure the sink cabinet is empty and spread a tarp or an old blanket on the cabinet floor to catch any water that is released while you work. Once you locate the cold-water shut off valve under the sink, take a piece of emery cloth and buff clean the copper tubing just directly below the valve. Use a close-quarters tubing cutter to remove a 1-inch-long section of tubing and discard. Brush flux onto the freshly cut tubing ends and a ½-inch copper tee fitting. Slip the tee onto the tubing below the shutoff valve and solder it in place. Be sure to protect the cabinet with a fire-resistant cloth or metal shield.

Step Three: Solder on a new shut-off valve
Fit a ½-inch ball valve to two pieces of copper tubing and a female adapter, as illustrated at far left. Solder the assembly together before installing it under the sink, for maximum safety. Work from the bottom up, first soldering the copper tubing to the ball valve, then the ball valve to the next bit of tubing, and finally the tubing to the female adapter. Fit the assembly onto the tee fitting coming off the cold-water supply with a 90-degree elbow. Solder both ends of the elbow in place. Wrap Teflon tape around the reducer fitting and thread it into the top of the female adapter. Hold the adapter with pliers while tightening the reducer with a wrench.

Step Four: Drill a hole for the new filter faucet
Measure and mark a hole location for the filter’s faucet on the sink deck. Drill a ½-inch-diameter hole through the stainless steel deck with a step drill. Each graduated step on the bit is 1/8 inch wider in diameter than the previous step.

Step Five: Install the filter faucet
After drilling the faucet hole, use a wet/dry vacuum to collect the metal chips from the sink top and from inside the cabinet. Now place the washer, aluminum base (escutcheon), and rubber gasket onto the threaded stem of the filter faucet. Slip the faucet into the hole and make sure it sits flat on top of the sink deck. From inside the cabinet, reach up and place the mounting bracket, lock washer, and hex nut on the faucet’s stem. Tighten the hex nut carefully with a basin wrench to secure the faucet.

Step Six: Attach the plastic tubing to the filter
Remove the plastic cover from the top of the filter and install the 9V battery, which powers the electronic filter monitor. Next, cut a length of the plastic tubing that comes with the filter kit to reach from the reducer fitting on the cold-water supply line to the filter’s mounting location on the back wall of the cabinet. Push one end of the tubing onto the inlet fitting on the left side of the filter. Cut another length of tubing long enough to extend from the outlet fitting on the right side of the filter up to the faucet stem.

Step Seven: Mount the filter in the cabinet
Select a spot on the back wall of the sink base cabinet to mount the filter; mark two screw holes, spaced to match the keyhole slots on the back of the filter. Drive a screw into each hole; stop when the screw heads are about ½ inch from the cabinet’s surface. Align the keyhole slots with the two mounting screws. Push the filter flat against the cabinet wall, then pull down to lock the keyhole slots onto the screw heads.

Step Eight: Connect the filter’s water-supply tubing
Attach a compression fitting onto the end of the plastic tubing that’s connected to the inlet side of the filter. Thread the compression fitting onto the reducer that’s attached to the cold-water supply line; tighten the fitting with a wrench while holding the reducer with pliers. Connect the other length of tubing to the outlet side of the filter and to the faucet stem, using a compression fitting. Open all the shutoff valves and check your work for leaks. Remove the aerator from the sink’s faucet and turn on the cold water for a minute or two to flush out any flux. Finally, open the filter faucet and let it run for five minutes to remove air and carbon particles from the cartridges.

Instructions brought to you by: This Old House

What did you think? Were these instructions simple and easy to follow? Did you successfully install your own water filter? Do you have a better way of installing the necessary hardware? Leave your suggestions and feedback in the comments section below!

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