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 household issue and could pose a risk to health along with its unpleasant appearance. It is most commonly caused by humid environments, damp surfaces, water damage, or leaky pipes.

This guide will help you understand how a dehumidifier could assist you in preventing and controlling the mold problem in your home and if a dehumidifier will kill mold or not.

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.

It’s not known exactly how many types of mold are out there, and while some may not appear to cause any harm, 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), or toxigenic (producing harmful or toxic molecules that may cause significant harm).

Molds at Home

The kinds of mold you are most likely to find in your home are:


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.

Signs You Could Have Mold in Your Home?

Constant Sickness

While a little exposure to mold is to be expected, 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 spores can also impact people with asthma.

Bubbly Walls

If your painted walls begin to bubble, it’s a sign that mold may be present, especially if it’s in an area prone to moisture.

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 humidity on a regular basis.

Water Damage

Moisture, 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, therefore leading to a higher chance of mold growth.


Another problem caused by humidity and excess moisture can be rust. If rust is present in your home, it’s quite possible there may be mold growth too.

Will a Dehumidifier Kill Mold in Your House?

Dehumidifiers, as the name suggests, remove moisture and humidity from our living areas. They can be portable and easy to move between rooms. As excess moisture is one of the biggest causes of mold growth, a dehumidifier is a useful ally in the fight against mold.

However, using a dehumidifier will not kill mold already growing in your house. It may slow the growth of existing mold patches and will prevent new growth, but it won’t remove existing growth.

Man Taking Photos of Molds in an Old Building

By pulling the moisture from the air, along with contaminants like pet dander, dust, mold spores, and more, dehumidifiers can clean the air we breathe and deal with the root of our mold problems. They can also deal with the musty smell that often accompanies mold and mildew. 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.

The biggest difference between portable dehumidifiers will be their filtration method and their drainage system. Mechanical filtration is by far the most efficient and safest way of cleaning your air. Both ionizers and ozone generators are less effective at removing air pollutants and may even pose a health risk. The water vapor collected by dehumidifiers may need to be drained by hand or may require a tube that is fed outside to let gravity do the draining for you.

Along with portable dehumidifiers, whole-house ventilation dehumidifiers remove moisture from your whole house via a unit situated in your loft. Models may also be placed in basements or crawl spaces as these are also prone to developing mold, mildew, and damp issues.

Effectively Using a Dehumidifier to Help with Mold

Before Using Your Dehumidifier

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. Should your humidity be 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.

To give your dehumidifier its best chance of helping your mold problem, 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
Setting up the Dehumidifier

Be sure the dehumidifier you will be using is suitable for the space you will be using it in. 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.

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!

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

See bathroom dehumidifiers here

See basement dehumidifiers here

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, and they should still be removed.

Can a dehumidifier spread mold spores?

If not cleaned and maintained regularly, dehumidifiers can become a source of mold growth 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 growing inside your dehumidifier, you can clean the unit with a white vinegar solution mixed with water. 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 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.


Mold is unsightly and potentially harmful to our health, but it can be effectively tackled and prevented with helpful appliances like dehumidifiers.

Last Updated on July 27, 2021

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.