“How long should I run my dehumidifier every day?” This is an excellent question. I get asked by everyone, whether they’ve had a dehumidifier for years or just started using one.

The best answer would be to run your dehumidifier unit 24 hours a day. However, that could end up costing quite a bit of money, and more than you really need to spend.

The Extraction Rate

The idea is to run all the air through the unit as much as possible. This is called your Extraction Rate, and it’s pretty difficult to determine. An average unit in your space, if it was operating correctly, should extract the moisture to around 50 to 55% Relative Humidity.

With this assumption, you can safely run your dehumidifier for about 12 hours a day. That should (again, depending on your unit) run all the humid air in your space through the system at least once. I usually tell people to run their dehumidifier for 10-12 hours a day, and of course, the more the better.

What About Costs?

If you’re concerned about spending too much on your electricity bill, you can try calling your energy company and asking about the “best times.” Usually, the best times to run your unit, that will save you money, is between 10 pm and 7 am — this is when less people are consuming energy, which drives down the rates.

However, if you’re drying your room, you need to have your unit running, and I doubt you’ll be doing this activity in the middle of the night. So it’s okay if you run your dehumidifier during normal hours from a couple of days to as long as required.

You could also split these times. For instance, you could run for six hours during the day and six hours at night. This is perfectly fine, however, you’ll want to get a timer to help you regulate this.

A timer is useful. Simply attach one to your power point and connect your dehumidifier. Especially great for if you’re running out the door to do errands, drying laundry indoors, or drying a painted wall.

The RH Factor

The ideal Relative Humidity or RH in a building is around 40% to 50%. Given that mould starts to grow at around 65% RH,  it is recommended that your home’s RH level stays well within ideal. Your dehumidifier is used to maintain that RH level.

A household produces 15 litres of moisture per day, bathing, cooking, washing, drying, breathing, sweating … However, properties vary in size, number of occupants, building materials, air flow, circulation, contents, occupant behaviour so there is no set limit about how long to run a dehumidifier.

When you first operate your dehumidifier, it would be good practise to run it continuously until the RH falls below the 60% mark or fills up the water tank, which ever comes first.  Once RH is below 60% you can then use the dehumidifier during day and off during the night.

If the RH has risen, the unit keeps working to bring the RH down and goes into sleep mode when the healthy RH level is reached.

You COULD Invest in Zeolite

If you have variable humidity spaces you can run a system for 24 hours a day without spending as much money as a standard dehumidifier. You can run at nominal costs when you’re just drying and freshening and consistent levels when you’re adding a permanent unit.

If cost is a consideration, I highly suggest you look into buying zeolite for any spaces that need a little something. They are the best bet for keeping your space dry and fresh and saving you money at the same time. I highly recommend them.


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Eliminates moisture, damp and musty smells safely and naturally from any wardrobe or room. Reduce mould, mildew, dampness, condensation, odours. Relieve symptoms any time of year! Around the clock protection.

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Or You COULD Invest In A Dampp Chaser

If value for money is important, I highly suggest you look into buying a Dammp Chaser for spaces that need more than expected. They are the BEST in keeping small spaces consistently dry and fresh. I more than highly recommend them.

Dampp Chaser

Eliminates mould, mildew, stagnant air in wardrobes and cupboards, pantries, linen closets, RV’s, boats, rental storage, basements. Reduce mould, mildew, dampness, condensation, odours in your wardrobe and protect your valuables.


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How Long To Run Your Dehumidifier?

So to recap, run your dehumidifier unit for at least 12 hours a day. This is a good rule of thumb. Again, it’s okay if you don’t stick to this schedule every day, but be aware that the more your family runs your dehumidifier unit the fresher and cleaner it will be all year long.

If you have any questions about running your dehumidifier, you can ask in the comments below and I will answer them quickly.

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Round the clock protection when you need it most! Reduce mould, mildew, dampness, condensation, odours. Relieve hayfever, sinus headache, influenza, sneezing, itchy eyes, stuffy nose, coughing, allergic rhinitis, asthma symptoms any time of year!

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Towards healthier living Carol Parr ♥

As Building Biologists, we have acquired knowledge of adverse health effects and recommend effective strategies to reduce occupants’ exposure by eliminating and controlling as many sources of pollutants in order to create healthy indoor living environments that are as exposure-free and natural as practically possible.

We cut out all the fluff and confusion of indoor air maintenance and stripped it down to the bare bones.

Carol Parr

Author Carol Parr

Carol Parr is a Building Biologist and Healthy Home Wizard. She has worked with asthma and allergy sufferers in their homes and work places for over twenty years, specialising in mould, dust mites, chemicals, EMFs and WiFi. When she’s not turning unhealthy rooms into healthier, relaxing and productive spaces, she’s most likely frightening her husband and their children with numerous “let’s see what this does when …” projects.

More posts by Carol Parr

Join the discussion 10 Comments

  • Bette scott says:

    What is the average setting for
    Dehumidifier? we wake up in morning to find all our windows
    Covered with water on the inside
    and our GE machine has collected
    No water. Got any ideas for us

    • Carol Parr Carol Parr says:

      Yes I do! I am unfamiliar with the brand however as a general overview – 1. the machine may be faulty. Check the machine over – clean filter; clean holding container; clean any inlets; motor will be encased for safety; ring GE for maintenance team feedback; motor may be operating inadequately even though you may hear the fan operating. 2. Relative Humidity Setting may be too high – set to 50-55% Relative Humidity, comfortable setting. 3. The machine capacity my be inadequate for the size of the room – we found 16 litre unit most suitable for bedroom, lounge/dining sized room. 4. Type of dehumidifier – a. Refrigerant dehumidifier operates efficiently (21-32 degrees celcius). b. Conventional refrigerant dehum operates efficiently at air above 55% gpp, the warmer and the wetter, the better! c. Low grain refrigerant dehumidifier dries air at a lower dew point 34-40 gpp. d. Desiccant dehum efficient below 30 gpp. Does that help?

  • Josephine Bentley says:

    hi Carol.
    I have a new dehumidifier and have just started running it 24/7 as it’s keeping the under the stoop area dry and clean.
    The stoop is well ventilated.

    Which months will the unit be the MOST expensive to run?

    Any advise re; settings, etc?

    i am in NJ.


  • Deb says:

    We run 2 humidifiers in our basement. They are full everyday. My daughters bedroom is down there so we worry about keeping the humidy down. I was wondering how do you know when to stop using them? Do they just no longer collect water? Can you take too much out of the air?

  • Charlie says:

    I’m thinking of putting a timer on my humidifier but the owners Manuel cautions that you should operate the unit by switching off or on the power. Says it may cause shock or fire due to heat generation. Unit is a keystone KSTAD70C. Thank you

  • Anika Walker says:

    My dehumidifier has to be changed often, like every 12 hours its full. I’ve had mold, mildew and dust issues in my apartment for years and it has affected my health, now I have a dehumidifier it is accumulating a lot of water. I still seem the mold in my apartment but it is getting a little better. what does that mean when it fills up fast everyday.

    • TRUONG DANG says:

      Hello Anika,

      Sounds like there is a lots of moisture in your home. Do you live in a basement apartment? Moisture is very dense and it will usually be in lower levels of homes. If it fills up fast every day, how big is your dehumidifier? Where do you put it usually? Check your walls and for leakage in the bathroom. All these are a factor.

  • kathy Prock says:

    I have been using my dehumidifier for almost 2 months at 12 hours a day approximately..
    I empty the bucket twice a day and clean the filter every couple days..
    tonight it started making a very loud humming sound which is unusual and I don’t know why…
    Am I ruining it by using it so much

  • Sticky&uncomfortable says:

    I just moved into a rental home that was built on a concrete slab, and holy crap there’s a lot of moisture in the air! I was given a used 70L dehumidifier and the humidity control seems to be broken, so it will only run on continuous mode. My home is approximately 900sq ft and I have to empty it every 6-8 hours. It’s seems the “bucket full” alarm isn’t working properly either so I really have to keep an eye on it or I’ll have to attach a hose for continuous draining. I’m very low-income and all utilities in the house are electric so I’m very weary of my 1st electric bill. With soooo much moisture, is it still possible to receive any benefit from running it 12 hrs/day, or is the moisture building right back up while it’s off? I also bought a bunch of packets of what my boyfriend calls some kind of volcanic rock? It looks exactly like the product you have linked to purchase in this article. How many of them would do you recommend for a 900 sq ft home? Thank you so much for this post, it’s been VERY helpful!!!

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