Can A Dehumidifier Overflow?

Dehumidifiers take moisture out of the air to help reduce the relative humidity of a space such as a room in a home.

The moisture is collected as liquid water in a collection tank, often located at the base of a dehumidifier to allow the water to drain into it via gravity.

Dehumidifiers typically have measures in place to prevent to prevent the water tank from overflowing, often in the form of an overflow switch. A faulty overflow switch can prevent a dehumidifier from turning off automatically when its water tank becomes full, potentially leading to overflowing water.

Our own dehumidifier uses a range of sensors and a float switch located within the water tank to automatically stop it from operating when the water tank becomes full.

Dehumidifier Power Control
Our dehumidifier tank light lights up red when it’s full

Your dehumidifier could also be overflowing for a number of reasons; it doesn’t just have to be the float.

Continue reading as we get into some of the other reasons your unit could be leaking and what to do about it.

Dehumidifiers Can Overflow

While modern-day dehumidifier units have systems in place to help them stop from overflowing, faults or damage can occur that can prevent the overflow-prevention systems from working.

The issues can vary slightly depending on whether you have a portable or stationary unit.

For instance, a portable dehumidifier will typically have a reservoir, and units installed in your home will typically have a drain line.

Dehumidifier Water Tank Leak
Our water tank when it’s full

Regardless of whether one has a unit installed or uses a portable dehumidifier, overflowing and leaking can be a common occurrence at some stage of a dehumidifier’s life.

While some dehumidifier units may have further overflow prevention systems in place to help prevent leaks, it’s probably not worth waiting to find out!

What Causes A Dehumidifier To Overflow

If you find that your dehumidifier is rehydrating your floors, then it’s time to get to work before any real damage occurs. Rather it’s a portable unit or fixed the issue because they are the same with slight variation.

Here or some of the things you’ll need to check:

  • If you are using a portable system, then the reservoir could need emptying
  • If you’re using a fixed unit, make sure there are no line blockages
  • Check the float, overflow switch or any sensors for faults
  • Does your dehumidifier use gravity or a pump to remove the water collected? If it uses a pump, make sure it’s operating correctly
  • If you’re operating your unit at lower than 65 degrees F, it could have frozen up, interfering with its ability to drain properly

These are some of the most common issues of an overflowing dehumidifier, and they aren’t tough to fix, especially if you know your way around a toolbox.

How To Find And Fix An Overflowing Dehumidifier

The first thing you’ll need to do is power down your dehumidifier, unplug it, cut the circuit breaker—whatever you do, just make sure that there isn’t any power going to the unit.

You never want to work on anything that may have a live wire as that’s an easy way to have your day ruined!

Check The Reservoir

Checking your reservoir only applies if you have a portable unit, and it’s not necessary to cut the power for this step. All mobile units have a water reservoir where the moisture from the air is collected.

Dehumidifier Water Level
The removable water tank in our dehumidifier

This container should be checked and emptied regularly to prevent it from becoming moldy and stagnate.

It’s unlikely that a dehumidifier will leak because they will shut off when the tank becomes full. However, any fault may prevent this automatic shut off feature from working properly.

This reservoir is usually located at the bottom of the unit and is easily accessible.

When you pull the container out, whether it’s full or not, make sure to check the filter for any obstruction or debris. The filter is usually located in the reservoir that holds water.

Dehumidifier Water Tank
A damaged reservoir could cause overflowing of water

Check The Float

Modern dehumidifiers have measures to keep their containers from overflowing, but it’s still possible for it to malfunction. When this happens, your dehumidifier can begin to overflow without even knowing that it is full.

What to do if you think the float has a fault.

  • First, cut the power to the unit
  • Disconnect the leads and attach a voltage meter to the terminals
  • Empty the container and check the filter
  • Set or voltage meter to RX1 and trip the lever

If your meter doesn’t move, then here lies your issue. You got two choices: go buy another one or make sure to check the reservoir regularly and go float-less.

The manual to our own dehumidifier explains regarding the float:

Do not remove or damage the float switch in the water-tank, otherwise the machine will stop working.’


Check The Hose For Any Blockages

Permanent dehumidifier appliances will have a drain hose attached to them to allow for the moisture to escape the unit.

If you find that your dehumidifier is overflowing, then this is the place to start.

  • Detach the drain hose from the unit.
  • Run your fingers up and down the length of the hose, checking for cracks, bends, and kinks.
  • Remove the drain hose altogether from the system and wash it. Make sure to send the water through the hose to check if there are any clogs. If the water runs out smoothly, the hose is not the issue, and you’ll need to continue to find the problem.

If you find that water is not passing through the hose or is trickling out, then you’ve found the issue. Simply install a new drain line. However, if you still have water coming through your drain line at a good rate then move on to the next step.

Are The Coils Freezing Up?

Most dehumidifiers aren’t designed to operate in colder temperatures. So, if you’re running yours in an area that is consistently under 65 degrees F, it might be freezing up.

Running your dehumidifier with frozen coils is a significant issue that can damage the unit.

Luckily, this is one of the easiest issues to fix. You raise the temperature of your dehumidifier’s location and let it thaw, wiping the coils off periodically until they are at the optimal operating temperature.

Is Your Pump Working?

Some permanent dehumidifiers are drained by gravity, but not all of them. In many cases, yours may just use a pump. If that’s the case, then your overflowing problem might stem from there. If that is the case, it would be best for you to call a professional to fix the issue.

If you have gone through all the other steps and can’t find any issues, then the pump is likely a problem.

Here’s how to troubleshoot the pump:

  • First, make sure that the pump is on or receiving power
  • Make sure that the drain container is in place, if applicable
  • Make sure that the drain bucket actually has water in it
  • Make sure that the drain hose isn’t too long (check your owner’s manual)

If everything is as it should be, then your problem is with the pump. In this case, the best course of action would be to call a professional.


A dehumidifier is unlikely to overflow due to the number of prevention measures found in modern units that automatically turn them off when water reservoir tanks are full.

However, if you find that your dehumidifier is overflowing, there’s no need to call a repairman right away.

You can troubleshoot the unit and, in some cases, fix it yourself.

The troubleshooting process is simple: start with the easiest solution and work your way up to the hardest.

  • Check the reservoir and the filter.
  • Check the drain hose.
  • Check to see if there’s ice on the coils.
  • Check the float to see if it’s operational.
  • Lastly, troubleshoot the pump.

Most of the issues that cause overflowing from your dehumidifier are pretty simple to fix if you have a little handyman experience. When It comes to messing around with the pump, and you’ve never done it before, the best course of action might be to call a repair service; the same could be said about the float.

If it all seems a little overwhelming to you, don’t hesitate to check your warranty and call a professional. It’s always better to be safe than sorry.

Further Reading

Why Your Dehumidifier Is Leaking And How To Fix

Does A Dehumidifier Need To Be On All The Time?