How Long Does It Take for a Dehumidifier to Work?

A dehumidifier gets rid of excess moisture from your indoor air. If the summer is having the best of you, just get this appliance. You only need to consider the space rating.

But … how long does it take for a dehumidifier to work? Usually, a dehumidifier will take about 7 hours to fill up its tank. Therefore, you can only assume that you will get the humidity level that you aim for after running it for 5 to 12 hours. Depending on how humid the air was, it can take even up to 12 hours to reach the optimum indoor humidity level.

But let’s dig deeper into this question. Just how soon can you enjoy good air when you get the appliance running? Will the humidity level reduce immediately or it will take time? Of course, it will take time.

In this case therefore, you need to know how a dehumidifier works. But first, a disclaimer:

This article may contain affiliate links. Also, as an Amazon Associate I earn from qualifying purchases.

How Does A Dehumidifier Work?

A dehumidifier removes excess moisture from your premises by taking in air the moisture-laden air and giving out dry air. The moisture collects in a container/tank as liquid water, which you should empty often.

The unit can draw the moisture from your indoor air in two ways. Some dehumidifiers use absorption where a dry material absorbs the moisture from the air and blows out dry air. Others use refrigeration in which the moisture from the air is cooled.

The refrigerant dehumidifier is the most common. Here, a fan draws in the moist air into the unit. The air passes through the cold coils where the moisture condenses. The condensed moisture is collected in a bucket or a drip pan. The warm, dry air is then re-circulated back into the room.

How Long Will The Dehumidifier Take To Work?

By this, we mean the duration that it will take to get rid of the excess moisture in your house.

Well, the rule of thumb is, if you run the dehumidifying unit for the first time, it will take 12 hours to achieve the desired humidity level.

However, there is no fixed time since the duration depends on several factors. These include the following:

  • The type of dehumidifier
  • The capacity of the appliance
  • The indoor humidity level
  • The size of the space that you are dehumidifying
  • The indoor temperature

Remember to close the doors and windows so that the unit can function efficiently. If you do not, you will be dehumidifying your indoor air and more moist air will be coming in through the open windows and doors.

Type of dehumidifier

One type can take minutes to reduce the humidity level while another one may take hours.There are a few factors determining this.

When you buy yours, find out how much water it can draw from the air in one hour. That should give you a good idea of how much work the appliance can do.

If you have a large space to dehumidify, buy a dehumidifier rated for that kind of space. For example, the Ivation dehumidifier which you can buy on is rated for 4500 square feet.


This brings us to the next point, below …

Dehumidifier capacity

How much water can a unit extract in 24 hours?

Some units can remove 75 pints while others can do 50 pints or 25 pints. The high capacity units extract more water in a given time.

For example, to bring down humidity from 90 to 40% in a 50 sq. Ft. room, at 820F, a 50-pint unit will take 11 minutes while a 22-pint one will take 34 minutes.

So, you can go for a higher capacity dehumidifier so that you can save on energy costs. It will take less time to get rid of moisture.

Indoor humidity level

It will take more time for a dehumidifier to work if the levels of humidity are high than when they are low.

If, for example, your home leaked, your unit would take more time to reduce the moisture levels. This is unlike when you have the typical summer humidity.

How long do I need to use a dehumidifier after leak? You should use it for up to 48 hours. However, this will depend on factors such as the size of the area affected, materials damaged, and the level of humidity in the area.

You should use a higher capacity unit if you want to get rid of high levels of moisture. Therefore, if your premises is extremely wet, a unit that can remove 75 pints in 24 hours would be better than the one that can do 25 pints.

The size of the room

The time it may take a dehumidifying unit to work in a 500 sq. ft. room is not the same time it will take on a 2000 sq. Ft. room.

The larger the space, the longer the time the unit will need to work.

Indoor temperature

When the temperature is high, the level of humidity is high. Therefore, the dehumidifier can take longer to work.

How Do I Know If My Dehumidifier Is Working?

A unit that is working needs to get rid of the excess moisture to bring the level of relative humidity down.

You will know that your appliance is working when:

  • The relative humidity level starts to go down
  • The water tank fills up
  • The dry and warm air is coming out

How Quickly Should A Dehumidifier Fill Up?

The condensed moisture collected in the dehumidifier ends up in the bucket or drip pan. This will fill up as moisture is collected, and it will need emptying. Some models have a drainpipe, and so they don’t need emptying.

The time it will take a dehumidifier to fill up will depend on:

  • The size of the tank – The larger the container, the longer it takes to fill up
  • Humidity levels – When humidity levels are high, the dehumidifier will fill up more quickly
  • Dehumidifier capacity – A 75 pints unit will fill up faster than 25 pints one

If you have just started, it may fill up in about six hours. Again, this depends on the tank, the humidity level and the capacity of the unit.

When to Run the Dehumidifier

You may be wondering, when do I run the dehumidifier, for how long and can I run it constantly.

When you should run the dehumidifier depends on several factors. These include the level of humidity, the size of the room, and the capacity of the unit. Of course, we have explained these factors before.

When the levels of humidity are high, you may need to run the dehumidifier 24 hours a day. However, if the levels are low, you can run it at a given time, let us say in the morning or evening.

For a large room, you should run the unit throughout the day. The reason for that is that the unit needs more time to remove the moisture in a larger place than in a small one.

Remember, the more you keep the unit running, the more energy costs you incur. Therefore, if you want to save energy costs, you should run it when necessary.

Alternatively, you can go for energy-saving models. You can run these models continuously and save on energy costs. However, these may not be available for larger rooms.

Is it safe to run a dehumidifier constantly all the time?

You may be wondering, can I run the dehumidifier constantly and is it safe?

It is not in black and white as to when and how long you should run the dehumidifier. However, it depends on the capacity of the unit, the level of humidity, the size of the premises and the tank size.

For instance, a high capacity dehumidifier can remove moisture in a short time. Therefore, you may not need to run it continuously.

The levels of humidity will also affect how long you run the unit, and so does the size of the tank.

If your unit has a small tank, you will have to drain it more often. This will prevent you from running it continuously. To solve this problem, you can get a unit with a drainpipe.

If there is rain or you have had a leak, you may need to run the unit continually.

Therefore, yes you can run the dehumidifier continuously if the level of humidity is high, the unit has a large tank or a drainpipe, it has a small capacity and the area is large.

Is a dehumidifier safe?

You want to leave your dehumidifier running all day and night, and you are wondering, is it safe.

To run it safely constantly, your unit should:

Be able to turn off automatically – Most units have an automatic turn off feature such that they go to “sleep mode” once the indoor air reaches the required level of humidity or when the tank is full.

Have a tilt safety feature – If the unit topples over or tilts, the function stops the unit from operating to prevent damage.

Overheating protection feature – A dehumidifier uses a motor that can overheat because of constant use. The feature enables the unit to turn off when the motor is overheated and turn on when it cools off.


How long does it take for a dehumidifier to work? From 5 to 12 hours should be a good time. Also, you have seen the factors that determine how faster or slower this unit works.

These include the indoor temperature, the humidity level, the space rating for the appliance and others. The most important factor to consider is how much space your unit is rated for.

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