How to Install an Under Sink Water Filter in 10 Easy Steps

Have you ever gone to the sink for a glass of water and realized something wasn’t quite right? Perhaps you choose to drink bottled water instead, but now you’re remorseful about how many plastic bottles you’re wasting. There should be a middle ground where you don’t feel guilty about producing plastic waste and can enjoy a glass of water.

The good news is that an under-sink water filter could potentially solve these problems. As the name implies, these filters are installed beneath your sink and contain a separate drinking water faucet. Chlorine, lead, nitrate, viruses, and other contaminants may be removed from your water with these filters.

Even better, setting up an under-sink water filter is a straightforward task. You need some basic plumbing tools and a few hours, and that’s it; you can do it yourself.

Tools and Supplies You Need For Under Sink Water Filter

Tools and Supplies You Need For Under Sink Water Filter

You’ll already have everything you need if you’ve ever attempted a plumbing project around the house. Nonetheless, the installation method necessitates a few simple tools that can be found at any hardware shop, such as Home Depot, Menard’s, or online (e.g., Amazon).

Here’s a list of things you need:

Easy Steps to Install an Under Sink Water Filter

Easy Steps to Install an Under Sink Water Filter

Inside the cabinet under the sink, a cold water line is connected to the under sink water filter. If you have a RO system, you’ll need to build an additional water storage tank within the cabinet. Some under sink filters include a specialized filtered-water faucet, which needs an extra step.

Step 1: Close the Cold Water Supply Valve

A drainpipe and two incoming water pipes are visible when you open the kitchen sink cabinet. And out of which, you have to close the valve supplying cold water because the filter is just for cold water delivery.

Are you unsure about the water pipe to use? Here’s a hint: Open the sink’s hot water faucet. Then, to determine which line is hot, touch it. Leave that alone while you focus on the other.

Step 2: Remove the Cold Water Tubing

Remove the Cold Water Tubing

The connection to the kitchen faucet that provides cold water must be broken. By releasing the nut with a tool, you may remove the tubing from the waterline.

Step 3: Install the Adapter

Install the Adapter

Once done with dismantling the cold water tubing, connect the adapter to the feedwater line. Use a copper T-adapter with a branch to connect the tube.

  • To achieve a perfect seal, wrap Teflon tape across all threads.
  • Thread the T to the cold water line with caution.
  • Make sure that you tighten it properly. Use two sets of wrenches for a snug fit. Make sure that you don’t overtighten it.
  • Connect the copper T with the under sink water filter tubing.
  • Connect the plastic tubing to the shut-off valve. Cartridge changing is a breeze with this little valve.
  • Insert the nut that comes with the T-fitting.
  • To keep the copper insert in place, push it into the pipe.
  • Tighten up all the fittings.

Step 4: Drill a Hole in Your Sink

Drill a Hole in Your Sink

If your under-sink filtration system includes a filtered water dispenser, you’ll need to drill a hole in the countertop. You can use the pre-drilled hole as a soap dispenser. With that in mind, the usual faucet hole size is 35 mm (13.8 inches). If your countertop is granite, you’ll need a grinder to get the job done. Remember that it’s difficult, dirty, and may harm the granite if you don’t do it correctly.

Step 5: Install The New Faucet

Install The New Faucet

Now, you need to install that new faucet once you are done drilling a hole in your countertop. For this, you might require a helping hand to hold the tap on the top while you are tightening the fitting.

If you use a pre-drilled hole, it may be larger than necessary. Stick some putty below the faucet’s gasket to ensure no water leaks out. Use a set of washers, nuts, and brass inserts to connect the faucet with the filter tubing. Tighten the hose clamps.

Step 6: Mount The Filter System

For mounting the filter system, you need to place the filtration system against the back or side of the cabinet and mark the spots where holes will be needed. After this, use the drill machine to drill the holes in the marked spots.

Always ensure to provide adequate room under the unit for the housings to be readily removed. Also, because the system must support a lot of weight, ensure it is secured to the cupboard.

Step 7: Make The Plumbing Connections

Make the Plumbing Connections

Connect the filter stages to the connections you’ve already created. Next, locate the ports on the unit’s left and right sides. One is for water input, while the other is for water outflow.

The inner adapter on the filter head should be connected to the cold feedwater line. In the same way, you have to insert the tubing from the faucet and connect it with the external adaptor.

Step 8: Turn The Water Back On

Turn on the valve you had previously shut off. Next, slide the filtration system’s shut-off valve vertically to the tubing to open it.

It’s critical to open the valve carefully. Otherwise, the device might be damaged by the sudden high pressure. To remove any trapped air, push the pressure release button on the top.

Step 9: Check For Leaks

Examine all connections for any leaks or drips. Fix them as soon as possible.

Step 10: Allow The System to Flush

Turn the cold water faucet on and let it run for a few minutes. It’s critical to flush fresh filter cartridges and clean the line of any impurities. Use the water for dishes or irrigate your plants instead of wasting it. Finally, owing to your freshly fitted under-sink filter, you can enjoy the benefits.


With these facts and questions, you are going to be more informed about how to install the under sink water filter on your own.

Q1. Do under-sink water filters work?

If installed correctly, under-sink filters are able to do their job properly and provide you with safe, clean water.

Q2. Can you install a water filter upside down?

Yes, a water filter can be installed in any way:  vertical, horizontal, and even upside down.

Q3. Can I install a water filtration system myself?

Yes, for as long as you have accurate instructions on how to install a water filter, and you make sure to follow these instructions accurately.

Q4. How much does it cost to install a water filtration system?

The average cost for a basic water filtration system is around $500 for material costs, give or take. To have a water filtration system installed for your entire household would cost around $2000.


With few basic tools and some time to spare, the installation process of an under sink water filter is quite easy. Also, by installing these filters, you are cutting the harmful chemicals from your life while also helping the environment by eliminating plastic bottle waste!