Dehumidifiers That Help Remove Musty Odors

How a dehumidifier reduces musty odors

Musty odors in a home usually come from mold and mildew growing in damp areas. According to the EPA, the key to mold control is moisture control, and mold will not grow without water or moisture. By pulling moisture out of the air, a dehumidifier helps make the environment less hospitable for mold and mildew, which in turn can reduce the musty smell.

A dehumidifier works by drawing air over cold coils, condensing water vapor into a bucket or drain, and then blowing drier air back into the room. This process lowers the humidity level, but it does not remove mold that has already grown. If you see or smell mold, the CDC advises cleaning it up and fixing the moisture problem. For guidance on mold cleanup and prevention, read the EPA and CDC pages linked in the sources.

When shopping, you will see listings that state capacity in pints per day, which is a measure of how much moisture the unit can remove under test conditions. This figure helps you compare units, but the right choice depends on the size of your space and the conditions there. The ENERGY STAR buying guidance explains that capacity needs are based on room size and dampness, and it suggests oversizing rather than undersizing. See our guide to choosing a dehumidifier for an overview.

Listing features that support airflow

Airflow matters because a dehumidifier can only treat the air that passes through it. Listings often mention fan speeds, louvers, and air discharge direction. A unit with multiple fan speeds lets you run a higher speed when you want more air movement, or a lower speed for quieter operation. Louvers that swing can direct the dry air where you need it, such as toward a damp corner.

Another feature to look for is a washable filter. A clean filter keeps air moving freely and reduces dust buildup on the coils. The CDC notes that mold can grow on dust, so keeping the filter clean is part of general maintenance. Check the maker's manual for how to remove and clean the filter. For more on filter care, see our article on filter types and maintenance.

Placement also affects airflow. The EPA advises that air should flow freely in your home. When you set up a dehumidifier, follow the manual's instructions for clearance around the unit so that air can enter and exit without obstruction. Avoid placing it right against a wall or under a shelf. Learn more in our placement tips.

Drainage options for continuous operation

A musty odor often comes from a space that stays damp for long periods. To keep a dehumidifier running without constant emptying, consider a unit with a continuous drain option. This lets you attach a hose that routes water to a floor drain or sump pump, so you do not have to empty the bucket.

Listings may say 'drain hose included' or 'pump included.' A pump is useful when you need to move water upward, such as to a sink or window, because it pushes water against gravity. If you have a floor drain nearby, a gravity drain hose may be enough. Read the listing and the maker's manual to see what is included and what you need to buy separately. For a deeper look, see our article on drain options.

For spaces like a basement or crawl space, a pump can be a convenient feature. The ENERGY STAR page notes that some dehumidifiers come with a fitting for a hose that can be directed into a floor drain. If you are considering a unit with a pump, see the guide to dehumidifiers with pumps for more details.

Capacity and space considerations

The capacity you need depends on the size of the space and how damp it is. ENERGY STAR provides a chart that suggests capacity ranges for small to medium rooms and large rooms, based on conditions from slightly damp to wet. For example, a slightly damp small room might need 20 to 30 pints per day, while a wet large room might need 50 or more. These are estimates, not guarantees.

When you look at listings, you will see capacity groups like 30-pint, 50-pint, and 70-pint units. The site's guides organize picks by these stated details. For a basement, a higher capacity unit is often chosen because basements tend to be larger and more damp. For a bedroom or closet, a smaller unit may be enough. See our basement sizing article for more.

Remember that the capacity figure on a listing is based on a test standard, and the actual performance depends on your conditions. The DOE changed the test procedure in 2019, so newer models may show lower capacity numbers than older ones. This does not mean the unit is less effective; it just reflects a different test method. For more on capacity versus square footage, see our article.

Energy Star and efficiency

If you plan to run a dehumidifier often, you might want to look for the ENERGY STAR mark. ENERGY STAR certified dehumidifiers use more efficient coils, compressors, and fans, and they use about 20% less energy than conventional units. The program is run by the EPA and DOE, and you can check the ENERGY STAR product finder to see if a model is certified.

Energy efficiency is measured by the integrated energy factor (IEF), which is liters of water removed per kilowatt-hour. A higher IEF means a more efficient unit. This information is usually on the maker's page or the ENERGY STAR listing, not always in the product title.

Choosing an ENERGY STAR model can be a good way to reduce energy use, but it is not the only factor. Consider the capacity, drainage, and features that fit your space. The site's guide to Energy Star dehumidifiers lists models that carry the mark.

When to address mold directly

A dehumidifier is a tool for moisture control, but it does not clean up existing mold. If you see mold growth or a musty smell persists, you need to clean the mold and fix the source of moisture. The EPA provides guidance on mold cleanup, including how to identify mold and when to call a professional. The CDC also advises removing mold and fixing the moisture problem.

For large mold problems, such as areas larger than about 10 square feet, the EPA recommends consulting professional guidance. If you have health concerns, talk to a health professional before starting cleanup. The EPA and CDC pages in the sources offer detailed information.

In addition to using a dehumidifier, the CDC suggests keeping humidity levels as low as you can, using exhaust fans in kitchens and bathrooms, and fixing leaks. These steps help prevent mold from returning after you clean it up. For more on humidity settings, see our guide.

What to pick for your situation

Questions

Does a dehumidifier remove musty odors?

A dehumidifier helps reduce musty odors by removing moisture from the air, which is the key to controlling mold and mildew growth. It does not remove mold that is already present; you need to clean that up separately.

What features should I look for to help with odors?

Look for a unit with a stated capacity that matches your space, a continuous drain option if you have a floor drain, a washable filter, and adjustable fan speeds to keep air moving. A pump is useful if you need to move water upward.

How do I know what capacity I need?

Capacity needs depend on the size of the space and how damp it is. ENERGY STAR provides estimates based on room size and conditions, but the actual performance depends on your situation. It is better to oversize than undersize.

Can a dehumidifier prevent mold?

By controlling moisture, a dehumidifier helps prevent mold growth, but it is not a mold removal tool. The EPA states that the key to mold control is moisture control. If you have mold, clean it up and fix the moisture problem.