How to Fix a Whole House Water Filter That’s Leaking

Author: Jason Hollow - Published: 2021/09/15 - Updated: 2022/11/08

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Did you just spot a leak in your whole house water filter? There could be plenty of reasons, including incorrect installation, a loose canister, an over-tightened canister, hot water damage, an incompatible adapter, debris, etc. However, more often than not, an ill-fitting gasket is to blame.

Therefore, it’s essential to identify the problem first and then move on to the solution – that is usually quite simple. That said, it is not always easy to locate the origin of the leak. But don’t worry, our tips will help you identify the issue swiftly.

In this article, we shall walk you through all possible reasons for a leak in a whole house water filter, multiple solutions, and finally how to avoid further leakages.

So, here is our guide on how to fix a leaking whole house water filter!


When the leak is from the top:

  1. Turn the water supply off and depressurize the whole house water filter.
  2. With the filter housing removed, wash it down with soapy water and a soft brush.
  3. If necessary, replace the cartridge and O-ring.
  4. Reinstall the filter housing. Unless the manufacturer specifies otherwise, wrap plumber’s tape on housing threads.
  5. Restart the water supply and look for any leaks.

When the leak is from the pressure-relief button:

  1. Turn the water supply off, unscrew the filter housing, and remove the O-ring.
  2. Inspect the O-ring and replace or clean it as necessary.
  3. Apply silicone grease to the O-ring.
  4. Reinstall the O-ring and screw the housing back on.

When the leak is from a fitting:

  1. Examine and adjust the fitting. Don’t over-tighten to prevent damage.
  2. If the leaking persists, replace the affected component(s).

Why is Your Whole House Water Filter Leaking?

Whole house water filters perform exceptionally well for years and years at end. But like any appliance, they are not immune to regular wear and tear.

As mentioned before, a whole house water filter leak could also be the result of an incorrectly fitted housing. The key is to look for trouble spots: the housing, O-rings, or adapters.

Stay with us as we walk through each element individually, so you can quickly troubleshoot the issue.

water filter housing with filter cartridge

The Filter Housing

The most common source of a leak in a whole house water filter is the housing itself. So, let’s help you remove the housing without breaking it or flooding your garage.

Here is how to remove the housing of a whole house water filter to inspect it for leakage:

  1. To start, turn off the main water supply or the bypass valve installed next to the unit. You need to stop any more water from entering the filter. Once you have isolated the unit successfully, you can move on.
  2. Next, you must depressurize the whole house filter. To do so, open a few faucets around the house to drain all water. When the water supply becomes a trickle, turn off the taps.
  3. Next, press and hold the pressure release button on the filter to remove any leftover air in the filter housing.
  4. Slide the plastic/metal housing wrench over the housing and move it to the left. Once it’s loose, use your hands to unscrew the housing from the cap.
  5. Keep a tub or a small towel underneath the housing to catch any drips.

Housing Interior, Exterior & Threads

Now you can inspect the housing carefully to ensure there are no cracks on the sump or the threads. Due to an accidental increase in water pressure, it’s plausible; the plastic housing is damaged.

Unfortunately, a cracked canister needs to be replaced.


If you’ve never paid attention to the rubber O-ring that’s sitting comfortably in its groove at the top of the filter housing, now is an excellent time to examine it.

O-rings are doughnut-shaped rubber rings that are indispensable to any plumbing fitting. They ensure a watertight seal, so not even a drop can trickle out.

The O-ring will fail to work if it’s broken, inflexible, or has tiny nicks all over. Therefore, we always advise inspecting the seal at every filter change and replacing it if required.

Another mistake people make is that they don’t lubricate their O-rings. However, lubricating them is an essential part of the assembly process as it helps protect from abrasion or scuffing. Moreover, the addition of a lubricant may extend the service life of an O-ring by creating a barrier over its surface.

Always use FDA-approved silicone grease to ensure the gasket remains in perfect shape. It’s important to point out that vaseline is not a substitute for silicone grease. Quite the contrary, the application of vaseline on a rubber O-ring will cause it to disfigure.

Clean O-Ring Channel

Similarly, inspect and remove any debris on the groove where the O-ring sits. Sometimes, sediment gets stuck in the interface that disrupts the seal.

The Filter Cartridge

One glance at the whole house filter cartridge will give you a good idea of whether it’s badly clogged or in a functioning state.

Besides reducing the water pressure, a severely jammed filter will limit water flow inside the housing. When the water can’t move through the cartridge, it will start to leak from the top of the housing.

Some people incorrectly assume that their filters can’t clog since they always follow the manufacturer’s guidelines. Sadly, the time to change a whole house water filter can be different for each household, depending on the water quality and usage.

Therefore, always inspect the filter cartridge and identify the perfect time for replacements -neither too early nor too late!

Re-Check for Leaks

Done checking the filter case and its components? Once you’ve ensured everything is in working condition, it’s time to put it back together. Carefully assemble the unit making sure you don’t overtighten or undertighten the housing.

First, twist the housing onto the cap using your hands. Then use a wrench to tighten it just enough.

Turn on the water supply and examine for any more leakages. If the problem persists, it’s time to call your water filter technician or a certified plumber.

Help, My Whole House Water Filter Is Leaking From the Top!

Whole House Water Filter Leaking from Top Thumbnail

If your whole house water filter is leaking from the top, it’s usually because of a faulty O-ring. Time to get your hands dirty, or shall we say wet!

1. Shutting Off the Water Supply

First, you must turn off the water supply to the unit. If you are lucky, your unit has its bypass valve located right next to it. If not, it’s time to find your main water supply valve.[1]

It’s always a good idea to educate yourself on how to turn off the main water supply. Moving on to the million-dollar question: where is the feed water valve? It could be located at any of the following places.

  • Does your house have a basement? Then it’s probably on the interior wall somewhere along the front side of the house.
  • If your house is on a slab, look for it in the garage.
  • If you can’t find the valve inside your house, you need to find a small cement box near the front curb.

If it’s a wheel valve, turn it clockwise to stop the water supply. However, a ball valve can be turned off by bringing it perpendicular to the pipe.

Next, flush out remaining water and air from the pipelines to depressurize the filtration unit. Press and hold the small red button on top of the filter head to remove residual water and air from the housing.

2. Removing and Cleaning the Filter Housing

Twist the housing using a housing wrench. Only remove one filter at a time to avoid messing up.

Take the opportunity to give the housing a good rinse with soapy water. Then, allow it to air dry.

3. Replacing O-Rings

Inspect the star of the show, the O-ring, for any signs of wear and tear. Replace the O-ring and ensure it’s seated perfectly in its channel. It’s ideal to lubricate the O-ring before putting it back.

4. Replacing the Filter Cartridge

Unwrap the new filter cartridge and carefully slide it inside the housing. Ensure it’s seated perfectly inside and is not tilting towards either side.

5. Applying Plumber’s Tape

Another small but mighty plumbing essential is plumber’s tape. Also known as thread seal tape or Teflon tape, it’s not your average tape. The thin, usually white or off-white, tape is commonly used to seal pipe threads.[2]

Nevertheless, it’s crucial to use it correctly, or it shall bring more harm than good.

  • Always wrap it around in the opposite direction to the direction the housing will be turned.
  • Don’t wrap it loosely. Instead, keep a firm hand so that it cloaks tightly on the threads.
  • Don’t use more than 4-6 wraps.

6. Putting Everything Back Together

Reassemble the housing back to the cap. Remember, don’t over-tighten, or you’ll end up damaging the seal.

7. Checking for Leaks Again

You are almost done! Slowly turn on the water supply. It’s important to remember that you must never open the valve fully at once. A sudden influx of water pressure can strain the filter, and you might be stuck with a bigger mess.

Turn the water supply on slowly and gradually as you inspect the system for leakages. Hopefully, you are good to go!

How to Prevent Future Leaks

Here are a few tried and tested ways to prevent your whole house filter from leaking again.

Replace Filters According to Schedule

Replacing the filter elements on time will prevent excessive build-up. Thus, there will be fewer chances of a leak in the housing.

Don’t just rely on the manufacturer’s instructions or follow the schedule of your friend. Since the daily requirement of your household varies significantly compared to others, your filter’s service life also varies greatly.

Scurry to your filter as soon as you see the first signs of pressure drop. Moreover, maintain a log to keep track and estimate the next date when replacement is due.

collection of whole house water filters

Frequent Cleaning

Besides protecting your whole house water filtration system from mold and mildew, regular cleaning will result in fewer instances of leakages. Try to clean your filter at least twice a year with soapy water and a soft brush.

This should remove any debris or sediment from inside the housing. Also, wipe down the exterior and assembly line of the unit to keep the unit in the best shape possible.

Taking Care of O-Rings

O-rings play a vital role in ensuring the unit maintains a tight seal. Therefore, you must ensure that the O-rings are well lubricated and functional.

Insulating Outdoor Water Filtration Systems

Extreme temperatures and constant exposure to direct sunlight adversely affect a whole house water filter.

If the temperature goes below freezing point, the water inside the canister might harden up and burst the housing. Similarly, constant exposure to heat can cause hard plastic housings to chip or degrade.

Since your unit is not weather-resistant, it’s better to insulate it properly. For example, you may use reflective sheets to cover the filter or build a small shed around it using insulation material.


In conclusion, there are multiple reasons for why a whole house water filter can be leaking.

It could be the filter housing that’s causing the issue, or an O-ring and the filter cartridge.

Thus, you need to find out where the water is coming from first.

If your whole house water filter is leaking from the top, shut off the water supply and remove and clean the filter sump. Replace all worn-out O-rings. Next, replace the filter cartridge, apply Teflon Tape on the housing threads, and put everything back together.

Replacing your filters according to schedule, cleaning frequently and taking care of O-rings are critical steps if you want to avoid future leaks.

Further Reading


Meet Jason Hollow

Jason Hollow Jason is the founder of Water Masterz and head of content creation. After six years in the industry, he has tremendous knowledge and first-hand experience on all things related to water treatment.

His credo: Not a single American should have to drink unhealthy water at home.

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