Can You Leave A Dehumidifier Unattended?

Dehumidifiers help to reduce the relative humidity in a home by taking excess moisture out of the air.

This process can be lengthy and a dehumidifier may need to be left on for many hours before the water tank needs to be emptied, or the target humidity is reached.

It can be possible to leave many modern dehumidifiers unattended, as long as it’s left operating in line with the manufacturer’s guidelines. Dehumidifiers with humidistats and automatic shutoff will stop operating when the target humidity is reached, or the water tank is full. Many dehumidifiers can also be set up for continuous drainage using a hose.

While we don’t leave our dehumidifier running overnight, we do leave it operating unattended throughout the day.

If the target humidity has been reached or the water tank is full then we’ll simply find that it has automatically turned itself off.

Dehumidifier Water Level
Our dehumidifier automatically turns off after the water tank is full so we can’t leave it running continuously for days

Many dehumidifiers can also be hooked up to drain pipes for continuous drainage, removing the need to manually empty the tank.

You’ll learn more about advantageous features such as drainage connections, internal pumps, auto shut-off systems, and cordless dehumidifiers in the sections below. Concerns regarding a dehumidifier that is running nonstop will also be discussed.

Leaving A Dehumidifier Unattended

Dehumidifiers are designed to reduce humidity through removal of moisture within the air.

Modern dehumidifiers typically include features such as humidistats that will continuously monitor the current humidity and adjust performance accordingly, and float sensors that shut the appliance off when the water tank reaches full capacity.

While in the vast majority of cases it can be fine to leave a dehumidifier running while unattended, there can still be the potential for problems to occur.

Leaving your dehumidifier running while you’re away from home could lead to more significant problems than those posed by the presence of excess humidity. Chief among these concerns is the potential for water damage to occur.


The possibility of an overflowing water tank could be the primary reason why you wouldn’t want to leave a dehumidifier unattended for long periods of time.

Dehumidifiers come with reservoirs that collect moisture from the air. Once this tank is full, it will begin to leak onto the floor unless the unit is equipped with features that allow it to run continuously without issue, as discussed in the sections below.

How Often Do You Have To Empty A Dehumidifier?

Typically, you can expect it to take hours, not days, for a dehumidifier’s tank to fill.

Of course, there is no universal reservoir tank size, and humidity conditions vary by region, so you may have to empty your tank after a much shorter duration than this.

Dehumidifier Water Tank

Either way, you may see how this can soon become a problem if you happen to be away from your home for a few days.

The good news is that there are several ways that you can eliminate this problem (such as hooking a hose up to the reservoir).

Can’t You Just Turn A Dehumidifier Off?

Dehumidifiers serve a much broader purpose than just keeping the inside of your home comfortable.

They also detract dangerous mold and insect pests, which both thrive in damp conditions. If you are planning on being away from your home for an extended period, there are many benefits to being able to keep your dehumidifier running for at least part of the time.

How To Keep Your Dehumidifier Running Safely While You’re Away

The good news is that dehumidifiers are often equipped with features that allow homeowners to keep them running, reducing the risk of the tank overflowing and flooding the floor.

These include auto shut-off, drainage controls, and even cordless units that do not come with a water tank and can keep a small room free of damaging moisture.

Connect A Hose To The Water Tank

You should be able to connect a hose to the tank and run it to a floor drain, sump pit, or outdoors. This will ensure that the tank does not overflow and flood the area.

Unfortunately, dehumidifiers do not typically come with drainage hoses, so this is something that you’ll have to purchase.

  1. Take a garden hose and cut it to a length that is just long enough to reach the floor drain/sump pit.
  2. In most models, you’ll have to remove the water tank to access the drain cover.
  3. Make sure that the hose is lying flat on the ground.

You can often find drain hoses specifically designed for use with dehumidifiers.

Although we haven’t needed to, it’s possible to connect our own desiccant dehumidifier up to a continuous drainage hose.

Our owner’s manual states:

‘The dehumidifier has a continuous drain hole that can be connected to a plastic pipe. Water can plumbed in or drained into a sink, a larger receptacle or through the wall into an outside drain.’

Dehumidifier Water Tank
The drain hole on our dehumidifier is the slit at the front of the water tank

Drain Pumps

Some models of dehumidifiers come with drain pumps that are capable of forcing the water a further distance than a simple garden hose. This is a great feature to have if your dehumidifier is not located near a floor drain, sump, or sink.

  1. Connect the drain hose.
  2. Make sure that the pump has been turned on. There may be a switch on your dehumidifier’s control panel next to the turn-on knob.
  3. The pump activates when the bucket is full.

Auto Shut-Off Dehumidifiers

Many dehumidifiers also come with auto shut-off features.

This automatically shuts off the dehumidifier as soon as the water tank is full.

The water tank full indicator light on our dehumidifier

You’ll be able to keep your dehumidifier running unattended for a little bit without having to worry about using a drainage hose.

You may need to engage the auto shut-off feature with the flip of a switch or the turn of a knob, so be sure to consult the owner’s manual before expecting the dehumidifier to shut off on its own without any intervention.

Change The Humidity Level Setting

If your dehumidifier runs often, it may be best to change the humidity setting while you are out of town.

The ideal indoor humidity range is between 30-50%, so it wouldn’t hurt to back off a little bit.

This will help you save on electricity costs while you are away from home.

Many dehumidifiers have this feature, but it is not necessarily standard. So be sure to purchase a unit that allows you to change the desired humidity level if you plan on leaving it on while you are away from home.

Cordless Dehumidifiers

If power outages or electricity usage is a concern, then you can always go with a cordless dehumidifier. These are typically used to keep small rooms, such as bathrooms, dry and comfortable.

What To Do If Your Dehumidifier Is Running Constantly

Should your dehumidifier be running and collecting water nonstop?

No, ideally, there will be periods in which the dehumidifier is not running. A constantly running dehumidifier is usually a sign that something needs to be corrected.

  • It’s possible that you may need to upgrade to a larger dehumidifier.
  • Alternatively, you might consider purchasing a second dehumidifier to work in unison with the unit you already have.
  • There’s also a chance that the dehumidifier is malfunctioning.

A malfunctioning humidity sensor could also be causing the dehumidifier to be running all the time.

You may need to replace the humidity sensor assembly following instructions.

Can You Leave A Dehumidifier Unattended?

Dehumidifiers can be left running while you’re away from home, as long as the machine is equipped with one or more of the following beneficial features: drainage hose connections, internal pumps, or an auto shut-off switch.

You can also find dehumidifiers that work a little differently by absorbing small amounts of moisture rather than collecting it in a tank.

Further Reading

Can A Dehumidifier Run Constantly?

Does A Dehumidifier Need To Be On All The Time?

Can A Dehumidifier Sit On Carpet?

Can A Dehumidifier Be Used As An Air Conditioner?