Under Sink Water Filter Install

This post is to show how easy it is to install a heavy duty water filter under the kitchen sink to provide clean drinking water.

The goals of this project are to provide a high-flow, high capacity filter system that is easy to install by virtually anyone, requires no special tools, and has easily available parts and filters, so that I am not locked into a proprietary system. There are nine parts (including the actual filter) used in the install. All the parts, including the filter housing and filter, can be purchased on Amazon.com from several different vendors. Personally I got all the parts on Amazon except for the faucet. Many of the parts can be purchased from local hardware stores.

Backstory: last summer I was browsing through old parts at a local home resource store, where they sell used or preowned building materials. All the items are used and re-purposed, and for that reason they don’t cost very much.

I found a drinking water faucet that gets installed on a sink to provide a filtered source of water. The price was about a dollar, so I bought it and started thinking about what to do with it. Months later, after much trial and error, I finally had all the parts I needed and got it installed.

The parts list follows:

LASCO 06-9101 Angle Stop Add-A-Tee Valve, 3/8-Inch Compression Inlet X 3/8-Inch Compression Outlet X 1/4-Inch Compression Outlet, Brass


Anderson Metals Brass Tube Fitting, Connector, 1/4″ Compression x 1/4″ Male Pipe (2 required)

      $2.92 each

1/4″ icemaker water hose, Eastman 48383 Ice Maker Connector, 1/4-Inch Comp X 1/4-Inch Comp

      (2 required, lengths vary with application) $5.42 for a 1 foot hose, you’ll need to measure to find out how long your hoses need to be

Pentek 158117 1/4″ #10 Slim Line Clear Filter Housing


Pentek 244047 Mounting Bracket Kit for 1/4″, 3/8″ and 1/2″ Housings


Pentek EP-10 Carbon Block Filter Cartridge, 9-3/4″ x 2-7/8″, 5 Microns


Watts 116023 Standard Faucet, Chrome


Apache 99000322 1/2″ x 275′ Spool of Teflon Thread Seal Tape


I bought all the parts on Amazon except for the faucet, but I am providing a link to a typical faucet similar to the one I have. I ordered a bunch of different parts and adapters on Amazon to make the system work, and a few times I ordered the wrong parts. I also got sidetracked with other projects. So this project took months to complete, but that’s because I didn’t know what parts to get and is why I am listing them all here.

I got a carbon filter made for drinking water, but there are many different types of filters to choose from.

Step One, Install the Faucet:

It was very easy except that I needed to be under the sink on my back tightening the holding nut while my daughter held the faucet in place up top. You will need to have an available hole in the sink to install it, or alternatively, you can make a new hole in the counter. But make sure the faucet is placed so that it will pour into the sink!

These faucets are smaller than normal kitchen faucets and have a 1/4″ male compression connector on the bottom. This connector will be connected to one of the icemaker water lines. The other end of the water line will be connected to the “out” side of the filter housing.

So attach the icemaker water line to the fitting on the new faucet and let it hang for now. Note: don’t attach the hose before you install the faucet, because it will need to be removed to get the mounting nut on. Ask me how I know.

Step Two, Adapters:

Get the filter housing ready by applying white plumbing tape to the adapters. The filter housing has two holes, In and Out. The holes have 1/4″ female pipe threads (NOT compression threads).

The plumbing tape will go on the adapter’s 1/4″ male pipe threads that screw into the filter housing. Do not apply plumbing tape to the compression threads on the other end of the adapters, or any other compression threads! There are exactly two places the plumbing tape should go, and it is where the adapters screw into the filter housing. So wrap those threads with a half dozen layers of plumbing tape and screw the adapters in with a wrench as far as they will reasonably go.

Step Three, Filter Housing:

Attach the filter housing to the mounting bracket, and screw the bracket to the wall of the cabinet in the desired place. Install the filter in the housing.

Step Four, Install the Tee:

The existing kitchen faucet (not the new drinking water faucet) connected to the water supply line on a quarter turn stop valve. Actually there are two of these, one for cold water and one for hot water. I tapped into the cold water supply by installing the Tee fitting between the stop valve and the existing faucet hose.  Most modern stop valves have a 3/8″ male compression fitting on them to connect to the faucet supply hose. If your stop valve has a different sized supply hose connector, you will need to get a different tee.

Then I  turned off the existing faucet stop valve, removed the existing faucet supply hose, installed the Tee by screwing on the female 3/8″ connector onto it, and then connected the faucet supply hose to the Tee’s 3/8″ male fitting. This left a 1/4″ male compression connector available for the filter hose.

Step Five, Install the Hoses:

Connect the icemaker hoses. One hose will go from the Tee to the adapter at the filter housing marked “In” and  the other hose will go from the new faucet to the adapter on the filter housing marked “Out”.

Step Six, Turn on the Water and Check for Leaks:

Open the stop valve and check for leaking water. If everything has been tightened properly, there should be no leaks, but it is best to check.

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