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Dryer Vent Keeps Filling With Water? Here’s Why (+ How To Fix)

A dryer vent is in charge of carrying the hot air generated by the dryer and releasing it outside of your house. So, if the dryer vent deals with hot air, why is it regularly filling up with water?

Your dryer vent keeps filling with water mainly because of poor ventilation. If the vent can’t fully expel the hot and humid air released by the dryer, it’ll condense inside the vent leading to water build-up. This can happen if the vent is clogged, too long, has multiple bends, or is uninsulated.

In this article, I’ve put together a detailed breakdown of the various reasons why your dryer vent keeps filling with water. Following that, I’ve also shared a short guide discussing the proper technique to clean your dryer vent to ensure all the water build-up is thoroughly expelled.

Reasons Why Your Dryer Vent Keeps Filling With Water

Here are 5 reasons why your dryer vent keeps filling with water:

  • The dryer vents are dirty or clogged 
  • The dryer vent is long and has a lot of bends
  • The flex vent is crushed behind the dryer
  • The vent is not insulated
  • The vent cover is damaged

Let’s go over each of these points in more detail to learn why these issues cause water build-up and what you can do to prevent it from happening.

The Dryer Vents Are Dirty or Clogged

If you haven’t cleaned your dryer vents in a long time, that could explain why there’s water inside the vents.

As the dryer dries your clothes using hot air, it also expels the hot air to ensure the drying chamber doesn’t overheat and consistently operates at a constant temperature. The excess hot air is removed from the dryer through the vent collar. It’s then carried by the vent until it gets released outside.

You can check out this detailed article to learn more about how a dryer works.

Now, as the hot air is in contact with the wet clothes for a certain period, it also captures little qualities of lint and a lot of moisture. Some of the lint, dust, and other debris deposit inside the vents on their way out. 

With time, these “little” quantities of lint build up and clog the vents, making it difficult for the hot air to properly pass through them. Furthermore, the lint build-up can also absorb some moisture in the exhaust air, which turns into water droplets through condensation.

This is the most common way to get water build-up inside your dryer vents.

Thankfully, it’s also the easiest problem to fix. All you need to do is clean the dryer vents and remove all the lint and debris stuck inside, thereby stopping the water build-up. 

In fact, it’s super important that you clean your dryer vents at least once every year. A clogged dryer vent presents more risks than simply causing water build-up. For instance, if the hot air can’t properly escape, it raises the inside temperature and might become a fire hazard.

I’ve provided a detailed guide on proper dryer vent cleaning in a subsequent section.

The Dryer Vent Is Long and Has a Lot of Bends

Ideally, the dryer vent should come out horizontally from the dryer vent collar and go straight outside your home. This ensures all the hot air from the dryer escapes without interruption. 

Unfortunately, such a simple configuration is rarely possible. Most of the time, there’s a considerable distance between the dryer and the exterior wall. As such, you need to install long ductwork with many bends and turns.

As the ductwork gets longer and longer, it gives the hot air more time to cool down. If the vents are long enough, the moisture in the hot air will start to condense, leading to water build-up.

What’s more, if there are sharp bends in the ductwork, they become hot spots for collecting the lint and other debris carried by the exhaust air. With time, as the lint build-up becomes more substantial, it’ll interfere with the hot air, slowing it down and causing more water to build up.

As the water forms inside the vents, it creeps down through the piping and settles near the dryer vent collar. This makes it easy to remove the water. 

However, if the ductwork deals with really long vents, it can dip or sag under its own weight. This creates pockets that slowly start to collect the condensed water making it super hard to remove from the ductwork. With time, the water build-up can lead to mold and mildew.

So, how do we fix this sort of issue?

If you face problems with water filling up your long and curvy dryer vents, your best option is to install more efficient ductwork to remove the hot air from your dryer.

In a perfect world, we would like the dryer vents to be around 5-10 feet (~150-300 cms). But since that’s not always possible in practice, we try to keep the length below 25 feet (762 cm), which is somewhat manageable. 

Also, while measuring the vent length, you need to account for any bends and turns. Typically a sharp 90-degree turn is equivalent to 5 ft (150cm) of restriction.

With this in mind, you need to work out a new, shorter, and straighter pathway for the dryer vent. This should solve the water build-up problem. If necessary, also consider moving the dryer to a different position in your laundry room to make the ductwork more manageable.

The Flex Vent Is Crushed Behind the Dryer

Another common reason for exhaust obstruction, and thereby water build-up inside the dryer vent, results from crushed flex vents.

Right behind the dryer, you have the exhaust vent or the dryer vent collar, which connects to the dryer vent ductworks. Usually, there’s a flexible foil or vinyl duct directly attached to the exhaust vent, leading to the main dryer vent.

If the dryer is positioned too close to the wall, it can crush the flexible vent and thereby obstruct the exhaust air from properly exiting the system. As a result, you’ll notice water build-up near the exhaust vent. Your laundry room will also get warmer as all the hot air can’t properly escape through the ductwork.

That said, this is a simple problem to diagnose and fix.

Simply unplug the dryer, pull it away from the wall and unscrew the vent. See if you notice any abnormal amount of lint build-up in the ductwork. In case you do, it’s a strong indication that the flex vent was crushed. As such, as you reposition the dryer back in  place, avoid pressing it against the wall and leave a decent gap for the flex vent.

Also, if you suspect the flex vent was crushed, make sure that it’s not torn or dented. If it is, replace it with a new flex vent, as the old one would still interrupt proper airflow.

The Vent Is Not Insulated

Hot and humid air condenses more quickly when it comes in contact with a cold surface. Hence, if the ductwork is cold, either because it’s during winter or the vent passes through a cold region of your house – the attic or crawl space -, it’ll accelerate the condensation process. Ultimately, this will lead to water build-up. 

In fact, if the vents are cold enough, you’ll find water filling up even short-length vents.

Now to avoid this problem, you have two main solutions.

Firstly, you can route the vent through a warmer region of your house. However, this won’t be easy, and you’ll most likely need to hire a professional. As you can imagine, this will become an expensive fix for the problem. 

The next option is to thoroughly insulate the vents such that the outside cold temperatures don’t influence the hot, humid air inside the vents. For example, you can try applying the Johns Manville Fiberglass Duct Insulation (available on on your vents to protect them from the cold weather. This is a simpler and much more cost-effective solution.

The Vent Cover Is Damaged

Most dryer vents will have a vent cover, also known as a vent flapper, installed on the outside end of the vent pipe. 

It’s designed to only open to let out the hot air inside the vents. Other than that, it’ll remain closed so that critters and small rodents don’t climb into the ductwork. 

However, if the vent cover is damaged, it can potentially stay open all the time. As a result, small insects can climb into the vents and build nests which potentially clog up the vent leading to water build-up issues. 

Furthermore, cold air can also enter through the vent cover and lower the inside temperature of the ductwork. As a result, the hot and humid air coming from the dryer will easily condense, and the vent will start filling with water.

Now, you can easily diagnose this issue by heading outside and checking if the vent cover is open while the dryer is turned off. If it is, that might be the root of your water build-up problem, and replacing the cover should fix the issue.

How To Properly Clean a Dryer Vent and Remove All the Water

You’ll need access to some professional-grade tools to thoroughly clean out your dryer vent and remove all lint & water build-up to stop the ductwork from filling with water in the future.

I’d recommend you get this Eastman Dryer Vent Cleaning Kit (available on to help you out. It comes with all the tools you’ll need to clean all the lint out of your dryer vent, thereby removing all the water build-up.

Now, with the cleaning kit in hand, follow the below steps:

  1. Unplug the dryer for the power outlet to avoid any potential shock hazard.
  2. [Optional] If you’re using a gas dryer, turn off the gas supply. This will prevent any accidental gas leaks or fire breakouts.
  3. Pull the dryer far enough from the wall to access the dryer vent collar on the back end.
  4. Unscrew the dryer vent and disconnect it from the dryer.
  5. Take a dryer vent cleaning brush and loosen up the lint and debris stuck to the back of the exhaust duct.
  6. Use a vacuum cleaner and suck up all the lint inside the exhaust duct.
  7. Take the flexible rod from the kit and attach it to your drill.
  8. Set the drill to spin clockwise and start to brush in and out of the vent. Follow the same motion you use when cleaning your teeth with a toothbrush.
  9. Add another flexible rod using electrical tape to extend the reach of the brush and continue cleaning. 
  10. Keep adding more flexible rods to clean out the furthest depths of the vent.
  11. You can now repeat the same process from the outside of the dryer vent. If the vent cover/flapper is getting in the way, you can remove it for the time being and reinstall it after cleaning the vent from the outside.
  12. With your dryer vents all cleaned up, turn on the dryer and allow it to exhaust all the loose lint outside.

And that’s it! You have successfully removed all the lint and water build-up from your dryer vents. 

Of course, as with any DIY project, you run the risk of damaging a part or component in the process. For example, if you’re dealing with vinyl or foil ducts, you can easily tear or rupture them if you’re not careful during the cleaning process. 

As such, if you don’t feel confident, I’d recommend calling a professional plumber to help you out. After all, it’s always better to be safe than sorry.

Key Takeaways

If your dryer vent is filling up with water, it’s a telltale sign that you have a problem with the overall ventilation system.

The most likely problem is that you haven’t cleaned the vents in a long time, and they have become clogged up with lint. Also, long curvy vents can interfere with proper ventilation leading to water build-up.

Other than this, uninsulated ductwork and a damaged vent cover can also lead to water build-up in the dryer vents.


  • Jake Alexander

    Jake is a freelance writer from Pennsylvania who enjoys writing about science and sports. When he's not writing for Temperature Master, he can be found watching the NFL or playing basketball with his friends.

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