How to Install a Water Filter (4 Step Guide)

The four steps you need to install your under sink or whole house water filter.

If you’ve noticed your water could taste, or smell, better, you may want to consider using a water filter. A water filter can remove large particles and debris, but it can also rid your water of harmful microorganisms.

Once you’ve picked out the right water filter for your house, you’ll need to know how to install it. Let’s take a look at popular water filter models and what it takes to install them.

How to Install a Whole House Water Filter

If you decide to go with a whole house water filter, you’ll place your new filter close to where your water comes into the house.

The most significant advantage of using a whole house water filter is that all of the water you use in your house will have been filtered. This means you’re dealing with less sediment and debris in all your pipes. If there are harmful chemicals in your water, you’ll also be reducing your exposure with a whole house filter.

These filter types can be an excellent solution for heavy-duty filtering needs, like if you have well water. While they’re great for filtering your water, they do require more of an effort to install.

Step 1: Turn Off the Water and Drain the System

Before you do anything else, you’ll need to turn off your water source. If you know where your curb-side shut off is, we always recommend turning off the water here. Even if you don’t turn the water off, you should be aware of where it is. In the event of a plumbing emergency, you’ll already know where to head.

Make sure also to turn off the main water valve in the house. Again, this will be near where the water pipes enter the house. You may have an old-style flower knob, but most will have a clearly labeled lever that can be moved 90 degrees.

Once your water is off, it’s time to drain the system. Open a tap on the lower level or the one closest to the plumbing entrance. This will allow any water beyond or above that point to drain out of the system. You’ll then be ready to move on with your installation.

Step 2: Cut Your Pipe

Your new water filter should have come with a template to use during installation. Use this template to mark your pipes and use a pipe cutter to make the needed cuts. Once the pipe is cut, remove that section and file away any sharp edges on your new cut.

You’ll want a bucket handy for this step. Any water left in the pipe that may leak when you cut into it will collect in the bucket. This will save you from any unnecessary cleanup.

Location Is Everything

Remember to place your unit close to where your plumbing comes into the house, but allow enough room to access the water filter easily. You’ll need to replace the cartridge regularly, and you’ll want enough space to place a bucket underneath during maintenance.

Step 3: Attach Your Fittings and Position the Filter

Before putting your new filter in place, you’ll have to attach your brass fittings on both the input and output ports. Always install them according to the included instructions and follow that up with Teflon tape for the best seal.

Now, you need to position the water filter properly. The most important part of this step is to make sure the input and outputs are in the correct orientation. If they aren’t, the filter won’t work as intended.

Make sure to hold your unit as level as possible during installation. This will prevent any damage to the inner filter and allow the unit to work as it should. Tighten the fittings as needed, but don’t be tempted to overtighten, as this can lead to problems later.

Step 4: Turn Back on the Water

Now that your filter is installed, it’s time to turn back on the water. Start by turning your water back on at the curb. Once that’s done, you can turn your main house valve back on.

For this step, we recommend not rushing it. Turn the lever a little at a time, about a quarter of a turn. This way, if there’s a problem with the installation or a leak in the setup, you’ll know about it without it resulting in gushing water.

If there aren’t any leaks, you’re ready to get filtering. In just a few minutes, you’ll have the filtered water you’ve been looking for.

If there is a leak, check your connections and make sure there’s no mis-threading in your filter unit.

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How to Install an Under Sink Water Filter

These can be a fantastic choice for removing impurities from drinking water and water you use during food prep. You’ll find some space-saving models that are even appropriate for tight areas.

Many under sink filters use charcoal as their main filtering component. Charcoal is an excellent filter for purifying water from chemicals and heavy metals. However, most charcoal units don’t sufficiently filter enough to use with well water.

Always make sure you’re choosing the right filter for your filtering needs.

Step 1: Turn Off the Water

Since you aren’t going to be interrupting the whole house’s water system, it’s fine to turn off just the main valve in the house. You likely have a lever that’s also dedicated to your sink or kitchen area. Go ahead and turn that one off as well.

Open the kitchen sink tap to remove any water that’s trapped in the system. Once this is complete, you’re ready to detach the current cold water hose. To do this, you’ll need to use a wrench to loosen the connecting nut.

Place your bucket under the hose area while removing it. This way, leftover water won’t end up on the bottom of your cabinet. Once the hose has been removed, you’re ready to move forward with your installation.

Step 2: Affix Your Water Filter Bracket

Most under sink water filters will come with a mounting bracket. Place this bracket on the side of the cabinet where it will be installed and mark where you’ll need to drill.

Remove the bracket and drill your screws part-way. Once the filter is in place, you’ll be able to drill these in the rest of the way.

Choose The Location Carefully

You’ll be able to choose where you want your filter, but don’t forget that you’ll need regular access to it. You don’t want it too far from your sink area but will need to be able to replace the cartridge easily. It’s also a good idea to keep it somewhere where you’ll be able to identify a leak quickly, should one happen.

Step 3: Attach Your Plumbing Hoses

Once the bracket is installed, you’re ready to attach the plumbing to the new filter. If your filter hasn’t come with hoses, you’ll need to purchase these separately. Make sure you have the appropriate-sized connectors for the job.

You may want to use Teflon tape for this step as it can help give you a more secure seal. As with all things, don’t over tighten during the process; hand-tightening will likely be sufficient here.

Step 4: Place Your Filter and Make the Final Connections

Learning how to install a water filter can be a little intimidating, so it may ease your mind to tackle this step with a partner. That way, one person can turn on the water while the other monitors the new seal. This can help prevent unnecessary water damage in the event the filter’s not entirely secure.

Now that all the components are where they should be, you’re ready to hang your water filter. After it’s in place, go ahead and tighten down those screws you only partially secured.

Double-check your connections to ensure they’re sufficiently hand-tightened. When they’ve passed the test, it’s time to turn the water back on.

Start by turning on the main water. After that’s back on, turn to the sink’s water valve. You’ll want to open this a little at a time. This allows the system to repressurize slowly so you can turn it back off quickly at the first sign of any leaking.

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Change Your Filter Regularly for Best Results

Now that you know how to install a water filter, make sure you change that filter regularly.

Your specific water source impacts how frequently you should change your filter, and each should come with recommendations on when to change it. Just make sure you have all the equipment you need before you get started and you’ll have the new filter installed in no time.

Have a water filter question or recommendation? We’d love to hear about it. Leave us a note in the comment section below.

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About the Author

Peter Gray

Peter has been a homeowner for 35+ years and has always done his own repair and improvement tasks. As a retired plumber, Peter now spends his time teaching others how they can fix leaks, replace faucets, and make home improvements on a budget.