Informational Guide

Will A Dehumidifier Kill Mold?

This guide helps you understand how a dehumidifier could assist you in controlling the mold problem in your home.

by Josh M

Mold is a common issue that can cause a lot of problems. Dehumidifiers can be powerful tools for managing your indoor environment, but can a dehumidifier remove mold? Or will the dry air blowing in your home make things worse?

The good news is that dehumidifiers can help with mold, and I’ve used them for years to prevent mold. In this guide, I’ll explain how a dehumidifier could assist you in preventing and controlling the mold problem in your home and what you can do to help stop mold growing.

Why Mold Is An Issue In The Home

Mold is all around us. It enters our homes as airborne particles. A small amount of these mold spores are harmless, but they may become a little more of a problem if they find a damp surface to grow on.

Damp homes with mold can be harmful to your health. They can cause respiratory problems, trigger allergies, and have an effect on your immune system [1]. Not only that, but mold can also cause damage to your belongings and if it spreads too far it can damage your home too.

It’s important to prevent mold growth and remove mold wherever possible to keep you, and your home, in the best condition. Dehumidifiers can be powerful tools to help you control mold levels in your home.

Molds at Home

Most Common Types of Mold in the Home

It’s slightly scary, but it’s actually not known exactly how many types of mold are out there. Some may not appear to cause any harm, but others could make your loved ones quite ill.

Molds that cause harm may be:

  • Allergenic – causing allergic reactions and asthma attacks
  • Pathogenic – which will impact anyone with acute illnesses
  • Toxigenic – producing harmful or toxic molecules that may cause significant harm

These are the most common types of mold that form in the home:


This allergenic mold is very common. Surfaces infected by it may feel velvety to the touch. It grows hairs that are dark green or brown, and may be present anywhere damp, such as in bathrooms or beneath sinks. It can also form around water damage.

This fast-growing fungus can impact health, with those exposed to it developing symptoms that mimic asthma.


This is a toxigenic mold, often found around humidifiers and air conditioning units. If left untreated, its appearance will change from moist and small into a fine powder. It can come in a variety of colors, such as gray, orange, white, or pink.

This is one of the most dangerous types of mold, with the potential to cause bone marrow or immune system diseases, and could even damage brain function due to its carcinogen nature. It can even team up with other kinds of mold and become even more dangerous.


This common mold is incredibly useful. Thanks to its production of penicillin, an important medicinal discovery was made. It is also used to make cheese, but this probably shouldn’t be attempted with any you find growing on your wall! Penicillium can be found on spoiled food.


This type of mold has over 185 species to its name. Its spores grow in thick layers in a flask shape in a wide variety of colors. It is allergenic, and in certain conditions, it could present more of a toxic risk. Exposure to it may cause asthma attacks, infections of the lung, and respiratory inflammation.

Black Mold

‘Black mold’ usually refers to Stachybotrys Chartarum. Some believe that this kind of mold can cause very serious health conditions such as mycotoxicosis. However, it’s very rare to develop this from mold infestation, and this condition is normally caused by eating moldy food.

All types of mold are capable of producing toxins, but few do. Although a study did find children brought up in a house with mold present may be more likely to develop asthma, Stachybotrys Chartarum was not one of the kinds most commonly linked with asthma.

How Does Mold Develop In Your Home?

Mold is an organic fungal growth that spreads over decaying matter. It goes in places of high relative humidity and where there’s a lot of damp, humid air [2]. It’s common in basements, roofs, windows, and pipes, but can also grow on walls, wallpaper, insulation, and wood products.

Mold spreads in areas of high humidity and moisture, which is why most mold remediation techniques involve using a dehumidifier (or another device) to improve indoor air quality and lower the relative humidity.

5 Signs That You Could Have Mold in Your Home

Constant Sickness

A small amount of exposure to mold is normal, but long-term exposure to mold growth inside your home could worsen some health conditions, and cause some new ones, especially if you have immune-weakening conditions.

You may be allergic to mold and experience coughing, congestion, and watering eyes. Your skin could become flaky, itchy, and dry, or even break out in hives. Mold can also impact people with asthma, which is why killing mold spores and taking mold remediation action is important.

Bubbly Walls

If your painted walls begin to bubble, it’s a sign that the humidity levels are high and that mold may be present. You should consider removing excess moisture and lowering the indoor humidity as soon as possible to prevent expensive damage.

Musty Smell

Mold doesn’t just look unpleasant; it can also create a noticeable musty smell. Keep a careful eye on any areas in your house that have poor ventilation or are exposed to moisture and high humidity levels on a regular basis.

Water Damage

Moisture, excess humidity, and water leaks are some of the biggest causes of mold. Should you have a leaky pipe or an easily flooded bathroom, watch out for mold. Take extra care in the winter, as heat increases can also increase indoor condensation and humidity. It’s worth remembering that for effective mold prevention and mold removal you’ll have to deal with the cause of the water damage first.


Rust is often caused by high humidity levels and excess moisture, so if rust is present in your home, it’s quite possible there may be mold growth too. Mold removal in these areas may also involve rust removal.

Will a Dehumidifier Kill Mold in Your House?

Dehumidifiers will not kill mold already growing in your house. However, dehumidifiers can slow the growth of existing mold patches and will prevent new growth by lowering the moisture levels in a humid environment. Dehumidifiers can also kill mold spores in the warm air, preventing them from spreading as far in your home.

How Does a Dehumidifier Help To Prevent Mold?

Mold and mildew growth is reliant on a high humidifier level and dampness to grow, and a dehumidifier helps to remove that moisture and humidity. They work by pulling in damp air and releasing dry air, which is key for mold remediation because it stops mold from spreading.

Dehumidifiers also pull in contaminants like pet dander, dust, mold spores, and more. This helps to improve indoor air quality and deal with the root of some mold problems. They can also help to stop the musty smell that often accompanies mold and mildew growth.

As excess moisture is one of the biggest causes of mold growth, a dehumidifier is a useful ally in the fight against mold. Dehumidifiers won’t remove mold, but they’re essential for mold prevention in damp areas.

Man Taking Photos of Molds in an Old Building

Which Type Of Dehumidifier Is Best For Mold?

There are two main types of dehumidifiers; desiccant dehumidifiers and refrigerant dehumidifiers. They both work to remove humidity from your indoor living space, and they will both work well at preventing mold.

It’s most important to get a dehumidifier that suits the job at hand. It needs to be large enough to cover the area, have enough capacity to remove enough moisture from the air, and be able to run for as long as you need it to.

Whatever your requirements, there will be a dehumidifier suitable for the job. Both large and small units are available, so be sure to check your size requirements before you buy.

Portable Dehumidifiers Vs. Fixed Dehumidifiers For Mold

Both portable and fixed dehumidifiers will help to prevent mold in your home if you use them correctly. The main difference is usually the drainage, as portable dehumidifiers will need to be emptied by hand whereas fixed dehumidifiers are usually plumbed in to drain automatically.

Portable dehumidifiers are best for those who only need dehumidification at certain times of the year, or in specific rooms of your home. If you have a big damp and mold problem then you should consider a fixed, whole-house ventilation dehumidifier. These will remove moisture from your whole house and help to remove mold before it even forms.

Dehumidifiers Vs. Air Purifiers For Dealing With Mold

Air purifiers don’t remove moisture or reduce the humidity level in your home as a dehumidifier does, but they can remove dust mites and mold spores from the air. This can stop mold from spreading around your home as it’s filtered through the air purifier.

An air purifier won’t remove mold, and won’t be as useful for mold remediation as a dehumidifier, but they can improve your indoor air quality and in doing so stop mold from spreading. It may be worth looking for a dehumidifier with a built-in air purifier so you can reduce the relative humidity level, while also improving the air quality in your living space.

5 Tips For Using a Dehumidifier to Help with Mold

1. Test The Humidity Level

Mold is able to grow generally in an environment that has between 50 – 65% humidity. By using a hygrometer, you can test your home’s humidity level as a first step in tackling any mold. If your humidity is over 50%, it may also be a good idea to have your home mold tested, either with an environmental contractor or via a home testing kit.

In order to make your home inhospitable to mold, it’s ideal to bring the humidity down to 35% if possible. Understanding your current relative humidity level will make it easier to choose a dehumidifier that meets your needs.

2. Clean The Mold

To give your dehumidifier its best chance of helping your mold problem you should first clean any visible mold growth. This can be done with bleach, vinegar, or cleaning products designed to kill mold. When using strong chemicals like these, always ensure the room is well-ventilated.

Woman Cleaning a Window

3. Choose The Right Dehumidifier

Be sure the dehumidifier you will be using is suitable for the space you will be using it in. To help your dehumidifier remove mold you need it to be the right size to cover the space and have enough capacity to deal with the moisture levels and indoor humidity.

Set up your dehumidifier in your chosen room – bathrooms, basements, and kitchens are often prone to mold. Different models will come with different modes – choose the model most applicable for the space it is used in. Some settings even claim to help your laundry dry quicker!

See bathroom dehumidifiers here

See basement dehumidifiers here

4. Program Your Dehumidifier

Use the dehumidifier controls so it is reducing humidity to an appropriate moisture level. Most dehumidifiers work by reducing the humidity to a certain % level, and you should try to keep it between 30-50% generally. This will help to alleviate allergy symptoms and stop mold from developing.

Turn on your dehumidifier, and enjoy the cleaner air supply and mold-free house.

5. Clean & Maintain The Dehumidifier

Check how often you will need to empty the water collected in the tank, or if you will need to set up a hose for it to self-empty. Find out how often your filters will need to be cleaned or replaced. The better your unit is cared for, the better it will work and the longer it will last, and the better it will prevent mold from growing.

People Also Ask (FAQ)

Will mold die if it dries out?

No, mold spores don’t die if they dry out, but they may become inactive. This still makes them a threat to health, but it should stop mold from spreading.

Can a dehumidifier spread mold spores?

Dehumidifiers can become a source of mold growth if they aren’t cleaned properly as they collect both mold spores and water. Always clean your filters and your unit, and drain the water as soon as possible after the tank has filled.

What can I put in my dehumidifier to prevent mold?

To stop mold from growing inside your dehumidifier, you should clean the unit regularly. You can use a specialist cleaner, or a white vinegar solution mixed with water which works well. White vinegar can also be used to treat mold growth around your home.

What humidity kills mold?

Humidity helps mold to thrive – to kill mold, reduce the humidity in your home to below 50%, or ideally down to 35%.

What kills black mold naturally?

The best natural remedy for black mold (or any type of mold) is white distilled vinegar. Mix with water in a spray bottle, cover the mold growth and allow to sit for a while before washing away.


Does a dehumidifier kill mold? No, a dehumidifier can’t kill mold if it’s already formed, but by reducing humidity and moisture levels in your home they can prevent it from forming and stop it from spreading.

Hopefully, this guide has helped to explain how powerful a dehumidifier can be in the fight against mold, and you now know how to use your dehumidifier most effectively.



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Last Updated on January 24, 2023

Josh M

My name is Josh and I am obsessed with the HVAC industry. I created this website to help HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and home air products so you can learn & buy with confidence. Learn more about the team here.