How to Change a Whole House Water Filter

Written by: James Smith

Updated: October 28, 2019

Read our guide on changing a whole house water filter, and get fresh filtered water again in no time.


One of the best things about a whole house water filter system is the ease with which you can change the cartridge if you need to.

We’ve created this comprehensive article explaining the reasons for why you might want to change your filter, as well as a step-by-step guide on how to do the job.

Some of the links below are affiliate links, meaning, at no additional cost to you, we may make a commission if you click through and make a purchase.

What is a Whole House Water Filter?

A whole house water filter (also called a point-of-entry water filter), is a system for filtering water from every outlet in a building.

It is fitted at the primary water supply, so then every single faucet in your home produces the same filtered water.

The alternative to this type of system is called a point-of-use filtration system, which is installed at individual water outlets to filter the water from that specific faucet. This is either installed on the countertop or under the sink in the chosen room.


Whole house water filtration means that all the water throughout the home is filtered: you can shower under, cook using and clean with filtered water, and access it wherever you are in the building.

A whole house system can be a more cost-effective and convenient alternative to individual, room-specific filtering systems.

If you want to know how to change a whole house water filter cartridge easily, safely and effectively, read on.

Reasons for Changing Your Filter

If you have a whole house system installed, one of the benefits is that you can easily change the cartridge and adjust the water in your whole house in one fell swoop.

Buying high-quality water filter cartridges means you’ll enjoy longer-lasting and more effective water filtration. High-quality cartridges can work for up to 3 years; others as little as 3 months.

Chlorine water filtration

Replacing your filter may be necessary to improve the performance of your filtration system. Signs that your cartridge needs changing include: a build-up of scale or dirt, an unpleasant smell or taste in your water, and poor water flow

If you’re unsure about whether it’s time to replace your cartridge or not, check the instruction booklet for the manufacturer’s recommendations.

Please note that a poorly functioning filter may not indicate a bad quality cartridge: it may simply be a compatibility issue. If you don’t get the right filter cartridge for the type of contaminants found in your water, it won’t work effectively.

You can assess which contaminants are in your water with a home water screening test. Pick one up at your local homeware store or order online. 

For more stringent testing, you can also hire a certified laboratory. Check out a list here.

How to Change a Whole House Water Filter

Once you’ve decided that changing your filter cartridge is the best option, it’s time to assess whether you yourself should do the job or get a professional in.

water filter icon

  • How Much Experience Do You Need?

Changing your cartridge is not a difficult job; in most instances, the manufacturer makes it easy to do without the help of a professional plumber.

You do not need to be an experienced DIY homeowner to change the average water filter. Consult the instruction booklet that came with your filtration system for more information as there are a few different varieties.

In most cases it involves just a few simple steps:

  1. Switching off the water flow
  2. Letting the filtration system drain
  3. Unscrewing the filter housing using a wrench
  4. Replacing the filters with a twist and a push
  • How Long Will It Take?

Changing a cartridge can be done quickly: even the most inexperienced DIY-er should be able to change a cartridge in under 10 minutes.

  • Tool Checklist

Here’s everything you need for the job:

  • A fresh water filter
  • A wrench (supplied with the system)

Curious how to install one of these systems? Don’t miss our beginner’s guide!

Water Filter Cartridge Replacement Steps

Every water filter system is slightly different, and you should always consult the manufacturer’s handbook before attempting to replace the filter cartridge.

Once you’ve read the instructions, it’s time to begin. These are the general steps that apply to the systems that use filter cartridges and filter housings (like the image below):

water filter and cartridge

Step 1: Turn off Your Water Supply

Locate the valve that controls the water supply for the whole building and turn it to off. If you have a bypass switch installed this will do the same job. This ensures that no water will be flowing through the pipes while you make the change.

Step 2: Remove the Cartridge from its Housing

Unscrew the cartridge from its housing (using the wrench that came with it), taking out the O-ring.

Give the O-ring a quick clean with a cloth and set to one side. Make sure you leave it in a safe place as O-rings are easy to lose. Discard of the used cartridge appropriately.

Step 3: Wash the Housing

Cleaning the housing is a vital step for keeping your filtration system in good working order. Once you’ve removed the cartridge, clean the housing thoroughly. Use warm soapy water with a ½ cap of bleach and a little scrub to remove dirt, dust, and sediment.

Step 4: Lubricate the O-Ring

Take the O-ring and gently rub a little silicone grease to make it lubricated. Then, return it to its original place inside the housing. The O-ring must sit level within its little indentation in order for the housing to be sealed.

Step 5: Replace the Cartridge

Take your new cartridges and carefully install them in the place of the old ones. They generally sit in the bottom of the housing.

Step 6: Screw up the Housing

Screw the housing in by hand. Make sure you don’t over-tighten this as this can make replacing the cartridges difficult in the future.

Step 7: Turn Your Water Back on

When everything is in place, switch the valve back on and allow water to run throughout the house. This will ensure the new filter takes effect. Ensure there are no leaks, and you’re done! You can now enjoy fresh, filtered water from every faucet in your house.


Replacing a whole house water filter is not complicated, but it can make a big difference to your quality of life, as well as the health of everyone who lives in your house.

Take care when replacing your cartridges, stick to the advisory instructions in the manufacturer’s manual, and if anything seems awry with your water supply, consider performing a water screening test. Good luck!

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About the Author James Smith

James is the chief water geek here at His mission is to empower the consumer and allow people to take control of their health. His passion for water health is contagious, hopefully unlike your tap water!

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  1. My whole house filter housing has three settings on top of the housing that you use the wrench to turn and set. They are “off, bypass, and filter.” Which setting should it be on to change out the filter and which setting should it be on continuously?

    1. The ‘bypass’ setting should route the water flow around the filtration system so it is not used. This is the setting that should be used for filter changes. Otherwise, I assume the ‘filter’ setting should be used to route the water through the filtration system.

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