Do Dehumidifiers Reduce Mold?

David J. Allen

I spent the better part of 2 ½ years learning about mold and indoor air quality because my child's life depended on it. Now I help others avoid ever having to experience the same thing. The mold industry suffers from conflicting opinions and I do my best to distill loads of data into something practical and useful. I love hearing from and helping readers. • "A house desecrated by mildew, mold, or fungus would be a defiled place to live in, so drastic measures had to be taken." — Leviticus 14:45

Though a dehumidifier may not quite be the powerful weapon against mold that some people think it is, having one can certainly help prevent the fungus from flourishing in your home.

While there are different types of dehumidifiers on the market, all of them share one primary purpose: Removing moisture from the air.

Installing one of these systems can bring a variety of benefits to your household, yet perhaps none are more appealing than the reduced risk of mold growth.

How do dehumidifiers help prevent mold growth?

Mold is a living organism, and just like all living organisms, it requires water to survive.

Granted, the presence of excessive moisture is only one of several factors that can lead to mold growth; the intrusive fungus also requires organic material and a temperature in the range of 50 to 70 degrees Fahrenheit to develop and expand.

However, without water, the other variables don’t matter, and a dehumidifier can help minimize the presence of water within your home.

Excessive moisture is the most controllable aspect of mold prevention. We can’t remove all mold spores (they are everywhere), we can’t remove the material they can grow on and devour (it’s used in all modern buildings), we can’t provide temperatures so extreme that mold doesn’t grow—at least not in our homes and offices.

“The mold spores will not grow if moisture is not present. Indoor mold growth can and should be prevented or controlled by controlling moisture indoors.”

U.S. EPA, A Brief Guide to Mold, Moisture and Your Home

Excessive moisture = mold

That leaves moisture as the single thing about the mold conundrum that we can control, and that mold experts recommend focusing on. In its most basic form, mold control consists of resolving (i.e., preventing from continuing to occur) the source of the excessive moisture, whether it be a leaking pipe, a flood, or accumulated water; drying the area out fully; and removing the mold-damaged porous material: drywall, carpet, clothing, couches, etc.

In a few cases (cases that are becoming increasingly common as more people begin making the connection between mold exposure and many long-term illness they have been experiencing), provided the mold isn’t widespread and the individual or home occupants aren’t highly sensitive to mold, affected porous material are best disposed of entirely.

There are numerous ways that mold can come in contact with the moisture that it needs to grow. A leaking pipe, a flooding basement, or even wetness on the walls of your shower can each lead to the arrival of a mold colony. Unfortunately, a dehumidifier won’t help you with any of those situations.

That said, high humidity levels are an extremely common cause of mold growth, and that’s where a dehumidifier does come in handy.

Not only can the fungus pull the moisture it needs directly from humid air, but oxygen with a high water content can also lead to significant condensation and a general dampness around your household.

Make no mistake: Having a dehumidifier won’t completely protect your home from mold growth, but there’s no question that it will greatly reduce the likelihood of mold growth or a mold infestation.

Specifically, a good dehumidifier will remove plenty of moisture from the air of the room in it is in, but it won’t, of course, prevent water leaks, prevent the accumulation of water in places it shouldn’t be, nor will a dehumidifier dry out damp building material—all of which mold can grow on.

But most people understand this limitation as it so apparent.

Will a dehumidifier kill existing mold?

In some cases, a homeowner will install a dehumidifier in hopes of eliminating an existing mold problem that they’ve discovered in their home.

While it’s a nice thought and has some logic behind it, it unfortunately doesn’t quite work that way. Although purchasing a dehumidifier is a prudent measure to protect your home from future fungal invasions, doing so will not eliminate an infestation that has already taken hold.

Once the mold has developed and begun to spread, the only surefire way to get rid of it is by removing it manually—either by yourself or with the help of mold removal professionals.

That said, running a dehumidifier may help slow down the growth of any mold colonies on your property.

The less moisture that the fungus has access to, the slower its expansion is going to be. Of course, in this case, the dehumidifier would serve only as a stalling tactic. If your home has a significant mold problem, your top priority should be finding a more permanent solution.

Usually, the ideal route is to enlist the help of mold remediation experts. They’ll not only remove the fungus from your household, but they’ll also help you improve the conditions of the home to prevent future infestations.

Dehumidifiers are a useful tool for preventing mold

As long as your entire mold prevention plan does not consist of buying and running a dehumidifier, they can be an excellent investment for helping you avoid mold growth.

Provided you view it as a preventative measure and don’t expect it to kill off all the fungus in your house, you should be satisfied with the difference it makes.

Keep in mind that other practices, such as keeping a clean home and staying diligent about moisture-related issues, will also go a long way toward keeping your household mold-free.