Do Dehumidifiers Prevent Mold?

Alison Kasch
Written by Alison Kasch
Updated December 8, 2021
Interior of modern bathroom
Photo: naka / Adobe Stock


  • Mold and mildew grow in areas of excess moisture and humidity.

  • Dehumidifiers control your home’s humidity to prevent mold and mildew.

  • A dehumidifier will not kill existing mold, but can prevent it from growing and spreading.

  • It’s important to inspect your home for leaks and excess moisture.

  • Hire a mold remediation specialist to tackle existing mold problems.

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No one wants to share their home with icky black spots and unsightly green fuzz, but excess humidity acts as an open invite. By controlling the humidity levels in your home, dehumidifiers make the offer of mold null and void. Here’s how a dehumidifier can help banish mold and mildew from your home for good.

Where Does Mold Come From?

Mold thrives in moist conditions, so it is prevalent in bathrooms, basements, or other areas where moisture is likely to accumulate. Anywhere that has a water source, is confined, or has leaks and cracks is also susceptible to mold infestation. 

Once mold rears its ugly head, patches can quickly multiply. Spores can also travel through the air, attaching themselves to unaffected areas and spreading even further.

In addition to the “ick” factor, mold and its spores can worsen allergies and cause health problems in some people, according to the Mayo Clinic. These include ear, nose, and throat irritations such as sneezing, coughing, wheezing, and stuffiness. Mold may also make you more susceptible to viruses and other illnesses, so keeping it out of your home is important.

How Can a Dehumidifier Prevent Mold Growth?

Woman changing water container in air dyer
Photo: Daria / Adobe Stock

Your home’s relative humidity, which is humidity in the air that is present versus what could be present, needs to remain at or below 45 to 50% to inhibit mold growth. Dehumidifiers monitor and control moisture levels, preventing the conditions that those pesky spores love. Especially if you live in a naturally humid location, they can be your go-to for maintaining a fuzz-free home.

Start by checking your home’s humidity with a hygrometer. You can also look for signs of humidity, such as moisture and condensation. If the moisture in your home seems excessive, consider investing in the cost of a whole-home dehumidifier. A few smaller ones may help control the situation, but not as effectively as a system would in most cases. Your best bet is to contact an HVAC technician to install a whole-home dehumidifier.

Will a Dehumidifier Kill Mold Spores?

Unfortunately, once mold and mildew have already begun to grow in your home, a dehumidifier won’t be able to intervene. The most it can do is prevent spores from spreading or keep them from forming in the first place.

Don’t worry, though—you’re not always stuck replacing anything that’s mold-ridden (unless it’s your insulation or other porous materials). If it’s a small section, locate the source of the moisture, don protective gear like an N95 mask, gloves, and goggles, and follow our steps to remove mold. Note that bleach won’t kill mold spores; it will only whiten them until they inevitably grow back. Instead, opt for a borax solution in hot water.

For areas larger than 10 square feet, it’s important to enlist the help of a local mold remediation specialist. They will help you salvage what you can, remove the existing mold, and determine how to prevent it from rearing its ugly head again in the future.

Keeping Mold and Moisture at Bay in Your Home

Mold and mildew are common issues, but that doesn’t mean you’re powerless in stopping them. Along with adding a dehumidifier, you can control humidity in your home and address moisture problems before they get worse. Here are the best methods to do it.

Install and Replace Insulation as Needed

Proper insulation is an excellent tool to keep your home mold-free. Damaged insulation can contribute to spore growth, so it’s important to inspect regularly and replace it when you spot signs of damage. Keep an eye out for condensation on windows and wet spots on the walls, as this usually means it’s time for insulation replacement. 

Check for Leaks and Excess Moisture

Inspect your home's exterior for mold-welcoming conditions. Repair roof leaks, remove rotting wood, and double-check AC units to ensure they’re working properly. Always remain on the lookout, especially after any stormy weather or flooding in your area.

Keep Your AC Running During Hotter Months

Running your air conditioner can do more than keep you cool—it dehumidifies the air as it brings temperatures down. During those hot, muggy days, run your AC as much as possible to prevent mold from moving in. Be sure to keep up with maintenance, too, as common problems such as broken pumps and blockages can lead to standing water.

Avoid Standing Water

Standing water is mold’s BFF, so be sure to avoid it around your home. Drain your kitchen sink as soon as you finish washing dishes and, if you take baths, don’t forget to pull out the stopper when you climb out. If your sink, bathtub, or washing machine has a blockage that hinders quick water drainage, remove the clog ASAP. In addition, don’t wait to fix any plumbing problems, and hire a local plumber for anything you can’t handle on your own.

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