Whole-house water filters aren’t designed to leak. Still, there are occasions when you might notice water escaping from your filtration system, usually due to cracks, faulty o-rings, or regular wear-and-tear.
We’ve been testing and using whole house water filter systems for more than a decade, and we’ve experienced several instances of leaking in that time. We’ve put together this guide, based on our own experience and information from some of the top whole house water filter manufacturers, to help you get to the bottom of your leaking filtration system – and put a stop to it once and for all.
Table of Contents
💦 Why is My Whole House Water Filter Leaking?
There are several reasons why a whole house water filter might be leaking:
- The filters are past their best. You may need to buy replacement filter cartridges to resolve the issue.
- The water system itself has reached the end of its lifespan. Best-case scenario: a few components need replacing. More likely: the whole thing needs to be replaced.
- The filtration system can’t handle the pressure of your drinking water supply. If you’ve bought the wrong sized system, you’re at risk of damage from water pressure.
- The system is poorly-designed and has broken.
- Your water supply has damaged the o-rings, the filters, or the connections. This is common with high-sediment water.
- You’ve over- or under-tightened the system’s threads.
🛠️ How to Fix a Leaking Whole Home Water Filter
First thing’s first, you need to know why your whole house water filter is leaking. This could be tricky if a lot of water is escaping from the system. Luckily, once you know the most common causes of leaks, you should be able to quickly and confidently diagnose the issue.
Follow the steps below to uncover and resolve a whole house water filter leaking problem:
Step 1: Identify the Location of the Leak
Before you do anything, it’s helpful to know exactly where the leak is coming from.
In some cases, this might be too difficult. But before you switch off your water supply and start the diagnostic process, it’ll save you a lot of time if you can figure out the source of the leak.
With a filter leaking from top, take a closer look to see exactly what’s causing the water to escape. Check for visible cracks that might indicate that you need to replace a part or component in your system.
If you can’t see any cracks from this quick visual inspection, check the threads. If you can’t see any leaking from the threads, the leaking is likely coming from a location inside the filter housing, and you’ll need to investigate further.
What are you most likely to find? Usually, a filter leaking from top is caused by cracks inside the filter housing, a faulty o-ring, or damaged threads.
Step 2: Take Off the Filter Housing
Most leaks from a whole house water filter come from inside the filter housing. Here’s how to safely remove the filter housing without causing major flooding in your home:
- Find the inside stop valve, which controls whether your main water supply can pass into your home or not. Turn the valve clockwise to shut off the water. Open a nearby faucet to release trapped air and drain the remaining water in the pipes.
- If your whole house water filter has a pressure-release button on the top of the filter housing, press this now. This will also help to relieve pressure in your water pipes.
- Some whole house water filters have a bypass valve. Turn the bypass valve for extra safety before accessing the filter housing.
- Place a large bucket or tray underneath the whole house water filter to catch any water that leaks out of the system.
- Follow your manufacturer’s instructions to remove the whole house filter housing. In some cases, you may need to use the filter wrench that came with your system to unscrew the filter housing counter-clockwise.
Step 3: Look for Filter Damage and Clogging
Filter cartridges don’t last forever – and some don’t even last within their expected lifespans.
High TDS and water hardness, or poor water quality in general, causes a filter to clog earlier than it should. Eventually, a clogged filter will become so saturated with contaminants that water will be unable to pass through.
In this case, the incoming water can’t travel through the filter as quickly as it travels through your pipes, so it’s likely to leak out of the fittings connecting the filter to your water line. Give your filter a visual inspection to check for dirt, and replace the cartridge if it’s close to the end of its lifespan.
If you don’t do this, you’re at risk of cracks and damage to the filter housing, so it’s important to change your filter as recommended by the manufacturer.
Step 4: Check the Inside and Outside of the Filter Housing & Threads
Overpressure inside a whole house water filter can cause the filter housing to become cracked, allowing water to escape from the system. Examine the filter housing to check for hairline cracks that could be the source of a minor leak.
The quicker you can find a crack in the housing, the better. Cracks can quickly expand and cause a major leak in your home. Be sure to check the inside and the outside of the housing, using a bright light (such as a torch) to check for cracks that may be difficult to see normally.
Once you’ve checked the housing, look at the filter threads. You may need to use more plumbers tape to secure the threads, or you may have over-tightened the connections.
Step 5: Look at the O-Ring
If you’ve checked every filter cartridge, your filter housing, and threads, and all looks fine, your whole house water filter leaking problem might be caused by a worn-out o-ring. After so many months or years of use, the rubber o-rings in your whole house filter become damaged.
Why is this a problem? Because the o-rings, despite their small and insignificant appearance, play an important role in a whole house water filtration system: they create a seal between the housing sump and the housing cap.
It’s important to keep your o-rings lubricated with silicone grease (food-grade) to prevent the seal from being compromised.
Check that each o-ring in your system isn’t hard, dirty, or damaged, or hasn’t vanished altogether. Resolving the problem may be as simple as rinsing the o-ring with water to remove a buildup of sediment, or you may need to buy a new o-ring to replace a damaged one. The good news is that o-rings are really cheap (less than $5) and widely available.
Don’t forget to lubricate any new o-rings you add to the system. In fact, lubricating all existing o-rings is a good idea whether you’re replacing them or not.
Step 6: Re-install the Whole House Water Filter
If you found no cause of leaks during the inspection of your whole house water filter, don’t panic. Sometimes, you simply need to reinstall the unit correctly to ensure no further leaking occurs. Something as simple as over- or under-tightening the connections can cause leaks.
Securely tighten the housing using the included wrench, and use plumbers tape to secure the connections and eliminate gaps that water could escape from. When you’re happy that your filter is secured, switch on your water supply and turn the bypass valve to allow water to flow back into the system.
If your unit still leaks, it’s worth getting in touch with your manufacturer to figure out what might be going wrong.
Related: 6 Common Whole House Water Filter Problems
✅ How to Prevent a Whole House Water Filter from Leaking
Once you’ve fixed a leaking water filtration system, you probably don’t want to repeat the process any time soon.
Fortunately, it’s easy to prevent a whole house filter from leaking again. Just follow these steps:
Buy the Right-Sized System
First and foremost, your water filter system should be the right size for your home.
If the system isn’t designed to handle your water pressure, the force of the water powering through the filters will cause cracks and damage. To prevent a water filter leaking from the moment you install it, make sure it’s designed for your home’s water pressure.
Manufacturers of whole house water filter systems usually offer systems in at least two different sizes: one for homes with 1-3 bathrooms and one for homes with 4-6 bathrooms. Don’t be tempted to save money on a smaller whole house filtration system if it’s not suitable for your home.
Replace the Filter Cartridges on Time
We mentioned earlier that one of the most common causes of a leaking whole house water filter is when a filter cartridge needs replacing.
It’s essential that you replace every filter cartridge as recommended by the manufacturer, not only for the sake of your health, but to prevent potentially catastrophic leaks in your main water line.
Check your user manual if you’re unsure how often each filter cartridge in your system needs to be changed.
Clean the System Regularly
Some whole house water filter cartridges last up to 9-12 months – and there’s a much better chance of them lasting this long with the right care.
You don’t need to buy a special water filter cleaner or a fancy cleaning tool for the job. In fact, these products and tools could end up damaging the filter or adding toxic chemicals into your water supply. Always use non-toxic cleaning products when cleaning your water filter system.
Twice a year, clean the inside and outside of the filter housing, removing bacteria, dirt, and sediment that has collected over its months of use. If you’ve bought your water filter from a good company, the user manual will provide specific instructions on how to keep your unit in a clean condition. Alternatively, you can read our in-depth guide on how to clean a whole house water filter system.
Lubricate the O-Rings
Lubricating the o-rings is such a small job that many people either forget to do it or think it’s unimportant.
Actually, if the o-rings are left to harden, they can affect the entire system, as they’re more at risk of cracking – resulting in leaking around the filter housing. So it’s important to lubricate them regularly.
A good routine is to lubricate the o-rings every time you change a water filter in the system.
Install (Or Replace) the Sediment Filter
Some whole home water filters come with a sediment filter that protects the later filter stages from damage.
High levels of sediment are abrasive and damaging to water filters. Not only will sediment clog the filters themselves, but it’ll get stuck in every rubber o-ring that surrounds each filter canister, causing them to lose their shape or harden.
If your water has a high sediment content and your system doesn’t already use a sediment filter, consider installing a standalone sediment filter to protect the system and prevent further damage to its components. Our best sediment filter guide has plenty of information about the sediment filters worth your money in 2023.
Replace the O-Rings
While you’re lubricating the o-rings, check each o-ring for cracks or damage and replace them if you notice any wear and tear (it helps to have an o-ring stash on hand just in case!).
Here’s how to replace a faulty o-ring in your water filter housings:
- Shut off the water supply and turn on your faucet to depressurize your water line.
- Press the pressure release button on your canister housing if you have one.
- Remove the filter sump and place the filter cartridge in a safe location. The sump is the bottom section of the housing.
- Once you’ve removed the sump, use a screwdriver to remove the small screw at the bottom, then remove the o-ring from the screw.
- Clean or replace the o-ring, depending on the extent of the damage. Lubricate the o-ring with a small amount of silicone grease or lubricant.
- Return the filter cartridge to the housing and tighten the screw. Return the filter sump back in place.
- Check for leaks around the o-ring. If the o-ring is properly in position, no leaks should occur.
Buy a Water Leak Detector
Water leak detectors won’t stop your filter’s housing from leaking, but they can alert you to a problem while it’s still pretty minor. This saves you from only discovering that your water filter is leaking when it’s reached a catastrophic, flooded-the-basement level.
For some people, leak detectors have saved them from extensive (and expensive) flood damage to their homes. You might not think they’re worth installing, but if you want to prevent future leaks on a huge scale, a water leak detector is the tool for the job.
You can buy a leak detector for less than $100, or pay a bit more for a smart leak detector. We’ve shared our favorite leak detectors in this guide.
Buy a Brand New System
In some cases, there’s no saving a whole house filter system with leaking filter housing. You might be unable to avoid water filter leaking if the unit itself is damaged beyond repair.
You’re most likely to experience this type of damage if:
- Your water pressure is too high for the filter’s design
- The water filter housing is made from poor-quality materials
- You’ve owned the system for 5-10 years or longer, and it’s simply time to buy a new one
If you’re on the market for a new water filter, consider a media-based system. Rather than having water filter housing, a media-based system contains a single tank, which is far less likely to become cracked or damaged, or experience leaking.
We have plenty of information about the best whole house water filters in this guide.