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Home » Water Filtration Systems » Whole House Water Filter Leaking

Whole House Water Filter Leaking

By: Craig Smith
Last Updated:
Whole House Water Filter Leaking

If you have made the investment it takes to purchase and install a single-tank or other whole house water filter system, then you are now enjoying some great-tasting tap water that is also much safer to drink.

You will also have a water filtration system that is designed to last a very long time and hold up well during the process. 

That’s why many whole house water filtration systems (sometimes referred to as whole home or point of entry water filters) also come with very good warranties.

Does this mean that point of entry water filters are always problem-free? 

The answer to that is no. Just like any type of device that has plumbing connections and water running through them, some leaking problems can arise throughout their lifetime.    

One of the most common of which is a whole house water filter leaking at the top of one of its filter canisters. 

That’s why I decided to put my many years of water filtration and plumbing experience to good use and talk to you about how to spot a leak on a whole home water filter and go about resolving that issue.

Identifying Why Your Whole House Water Filter Is Leaking

Unlike point-of-use water filtration systems such as reverse osmosis systems and under sink water filters, whole home water filtration setups will treat 100% of the water that comes into your home.

There are two types of these water filtration systems.


One is a single-tank water filter (often referred to as a media filter and pictured above) and the other features a series of independent filter cartridges working together in series.


Media filters very seldom if ever leak, that’s why for this article I will be referring to cartridge-style point of entry (POE) water filters (see photo above).

If you see some water puddling under your whole house water filter and don’t detect any other obvious water sources around it that can cause this, then most likely it’s your POE water filter that’s leaking.

The tricky part now is then determining where the leak on your whole home filter is coming from.

You will have to start by taking a closer look at your water filtration system. Be sure to do such things as checking the plumbing connections coming into the top of each filter cartridge and also check each filter canister for cracks.

To be honest, although inspecting these areas for leaks is necessary, 95 times out of 100 these will not be the source of your whole house water filter leak.

That’s because by far the most leak-prone area on any whole home filter is where the individual filter canisters connect to their tops that are hard-plumbed into the incoming water line.

Why is this usually the case? It’s because there are so many possible causes of leaks that will impact how watertight the seal is in these areas. Examples of this are:

1. The Threaded Connection Where the Filter Canister Bottom Connects to the Top

One of the nice traits of canister-style point of entry water filters is that the filter elements inside of them can be replaced when they become inefficient. That’s why each filter canister has threaded connections where the bottom screws into the top.

The drawback with these threaded connections is that the movement of water through the system can cause the connection to loosen and start to leak or they can leak if they were not tightened properly when the system was installed or after changing a filter element.

Cross threading when reinstalling a filter canister can also lead to a leak at the top of them.

2. Canister O-Rings

Even when the threaded connections on filter cartridges in a POE water system are fully tightened, they still may not mesh in a way that makes a watertight seal. 

That’s why manufacturers have added O-rings at the top of filter canisters to help make a better seal there.

There are several reasons why O-rings may no longer help prevent a leak between a filter canister and where it threads into its top.

The main one is that these O-rings sometimes become worn or disfigured and no longer function as intended. 

They may also not be seated properly into the grooves that hold them and they can also break which leaves a pathway for water to escape out of the filter canister top.

3. The Filter Canisters Themselves May Fail

As was mentioned, although cracks in filter canisters and other leak-related issues with them are unlikely, you still have to do your due diligence when searching for a POE water filter leak source and check them out. Cracked filter canisters cannot be repaired and need to be replaced.

Threads in a filter canister can also become stripped and this makes it unlikely that a filter cartridge can then make a watertight seal. The entire filter cartridge will then need to be replaced.

What To Do If Your Whole House Water Filter Is Leaking From The Top

Now that you know the most likely leak source on a canister-style whole house filtration system is the area where the filter canister screws into its top, you will need to know how to correct a leak there. The good news is this is something that you most likely can do yourself.   

Here are the steps involved to seal up a leaky filter canister top:

Step 1: Shut Off the Water Supply and Relieve the System Pressure

First of all, you never want to attempt to resolve a leak issue on the top of a POE filter system canister without first turning off the water and depressurizing the system.

You can do this by opening the bypass valves that were plumbed into your whole house water filter when it was first installed. 

Once this is done, there should be a bleeder plug screwed into the top of each filter canister (see the red plug on the top of the filter canister in the photo below).

One or more of these can be slowly opened to release the pressure in the system. Opening a bathroom faucet or two can also help depressurize the system.

Step 2: Remove the Leaky Filter Housing and Clean It

Now you can safely twist open the filter canister that is leaking at the top. If you can’t do this by hand, your system should have come with a special filter wrench for doing this (see below)

Each time that you take off a filter housing you also want to clean it and pay close attention to its threads while doing this. 

Just use a light dish soap mixture to do this. Be sure to clean the filter top in place too with the same solution.

Doing this will help make sure there is no sand or other grit in your filter canister’s threads that will keep it from sealing properly.  

Step 3: Check the O-Ring and Replace if Necessary

Now that your filter canister is apart, it’s a great time to inspect to see if the O-ring in the opening of the filter housing may be the reason that you have a leak at the top of your filter canister.


Worn or broken O-rings are very easy to spot (see above) and there is no way to salvage them so they must be replaced. 

It’s also a good idea to coat your canister O-rings with lubricant or grease to help them seat properly in the filter housing and stay flexible longer.

Step 4: Replace the Filter Element if It’s Time

While your filter canister is apart, it’s also a good time for you to replace the filter element if it is close to expiration or has already expired. Make sure that you replace it with the same type and style of filter cartridge that came out of it.

This is important for your point of entry water filter to reduce or remove all of the water contaminants that it’s intended to eliminate. 

Make sure this filter canister seats properly in the housing and does not stick out the top of it in a way that will prevent the filter canister from sealing tightly.

Step 5: Reinstall the Filter Housing

After steps 1 thru 5 have been completed it will then be time to re-thread your filter housing back into the filter canister top. Be careful when doing this not to cross the threads because this will drastically reduce your chances of making a watertight seal.

This can even necessitate filter canister replacement if it happens.  

At this time, you will also need to double-check that the O-ring is properly seated in the top of the filter housing.

Screw the filter housing back into the top of the filter canister slow and evenly. If it does not screw in easily then you are doing something wrong and need to back up and start over.

Snug up the filter housing tightly by using the same wrench that helped you loosen the filter housing to help take it off.

Step 6: Turn on the Water and Check for Leaks

Now it’s time to open the system bypass valves up and inspect to see if you have solved the leak issue at the top of your filter canister. Stay by the bypass valve for a minute or so just in case a problem arises while repressurizing the system.

After a few minutes have passed, then go ahead and check your POE filter tops to make sure they are not leaking.

Preventing Future Leaks

There are some steps that you can take to help ensure that your whole house filter canister tops do not leak. Here is what they are:

  • Follow the same steps mentioned above whenever you go to replace a filter element. They not only can help resolve leak issues but also stop new leaks from forming.
  • It’s especially important to keep your filter housing O-rings lubricated so they remain flexible enough to make a watertight seal.

You can do this by coating your system’s O-rings with special O-ring lubricants or silicone grease such as Super Lube 93003 O-Ring Grease.

  • In extreme circumstances (such as not being able to find a replacement O-ring), you can also add 3e to 6 wraps of Teflon tape (also called plumbers tape) to the threads of your filter housing.

Be sure to wrap them in the opposite direction you screw on the filter housing.

  • Change your filter elements on time. This will help to eliminate filter top leaks that are caused by too much pressure building up in the system because of dirty filter elements.   

A Few Final Thoughts on Leaking POE Water Filters

Chances are at some point you will experience a water leak at the top of your whole house water system’s filter canister. When this happens be sure to not panic because this is not a situation that’s hard to correct.

As was discussed, it’s something that can often be resolved by doing the repair yourself. If doing a DIY repair intimidates you, then you always have the option to call a local plumber or a handyman to come and fix that leak for you.   

If you feel that your leaks at the top of your POE water filter canisters are being caused because they are at the end of their useful life, then you may want to consider purchasing a whole new point of entry filtration system.

We have written a whole house water filter buying guide with reviews that will help you find a POE water filter that will keep you satisfied and easily handle your water purification needs well into the future.

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Craig Smith
Craig got his start in water working in the swimming pool and spa industry. Water treatment would grow into his main career but he ended up working in the pool industry for over 26 years where much of his time was spent balancing the water in customer's swimming pools and installing water filtration equipment. Craig offers an abundance of water treatment knowledge after helping homeowners get pure water for 26 years.

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