How to Choose the Right Dehumidifier for Mold, According to Experts

Damp basement walls, soggy insulation, and the telltale black specks of black mold—these are the stuff of nightmares no homeowner wants to face.

Unfortunately, if you live in an apartment building or a house built in the ’80s or earlier, chances are the basement or crawl space isn’t encapsulated. If it is, it likely doesn’t meet today’s standards.

The result? Persistent dampness that creeps into your home, especially during humid summers or those rainy stretches in fall and winter. And wherever moisture lingers indoors, mold is never far behind.

In relation to this, there’s a question that homeowners ask often:

“There’s mold or moisture in my home. What do I do?”

The answer almost always leads to one critical solution: controlling indoor humidity. But that raises the next big question: how do you know if you need a dehumidifier?

Read on to know what the industry experts and authorized organizations say.

What Are Signs of Mold in A House?

You can avoid property damage and health-related issues with early mold detection. Sadly, the signs aren’t always obvious at first. The National Center for Healthy Housing (NCHH) lists the following telltale signs to watch out for:

• A persistent musty or earthy odor that doesn’t go away.
• Discoloration or fuzzy patches on walls, ceilings, or baseboards.
• Peeling, bubbling, or cracking paint and wallpaper.
• Warped or rotting wood.
• Recurring condensation on windows or cold surfaces.
• Increased allergies and symptoms like “perpetual headaches, chronic fatigue, brain fog, weight gain.... and weight loss” (from mold expert, author, and IAQ advocate, Michael Rubino, in an interview with Jesse Chappus).
• Rusty nails and other metals

If you observe one or more of these in your house, it's time to look for a dehumidifier for mold defense.

The Role of Dehumidifiers in Mold Prevention

Dehumidifiers have a singular purpose: to remove moisture from the air. They combat indoor relative humidity (RH). Relative humidity is the amount of moisture air can hold at a given temperature.

The goal is to keep the RH below 60%, which the U.S. Environmental Protection Agency (EPA) recommends for preventing mold. Consumer Reports is in the same ballpark with 50% RH or lower.

“Will a dehumidifier get rid of mold?”

No, but it can deprive mold spores of moisture, which they need to thrive and spread. If mold infestation already exists, you still have to hire a mold removal specialist to remove the fungi.

“Can a dehumidifier stop mold from returning?”

Yes. By keeping indoor RH low, you’re creating a hostile environment for mold and preventing spores from taking root. The EPA recommends 30-50% RH for optimal moisture control and mold prevention in basements, attics, and crawl spaces.

“Can a dehumidifier prevent mold in bathroom?”

Certainly, as well as in the kitchen, laundry room, pantry, and walk-in closet, if you have one. If you can keep the indoor RH within the EPA-recommended range, the risk of mold infestation will stay low.

Things To Do Before Buying a Dehumidifier

1. Assess Your Humidity Problem

Do you live in a coastal town or state where humidity is a year-long problem? How bad is humidity in your house? Does dampness persist even when the air conditioner is on?

Humidity is a problem if the indoor RH persists at around 60% on an average day. This could exacerbate if it goes higher on warm days.

“If indoor relative humidity persistently stays above about 65%, that’s bad,” says Alec Watson at Technology Connections, a YouTube channel that produces long-form videos about the histories and mechanics of consumer technologies.

If the hygrometer reading in your home is often in the 60s, get a dehumidifier for black mold mitigation as quickly as possible. There’s a chance that moisture already lurks hidden all over your home.

2. Consider Your Location and the Availability of Dehumidifiers

Location and the local climate are major factors when buying dehumidifiers.

Logically, the supply and demand for them should be high in hot and humid states, like in the Midwest. Many houses in this region have dehumidifiers in their basements and living rooms. Because of this demand, many brands are likely available at local big box stores.

It’s different in dry regions and humid states like Florida where people are more reliant on ACs for home dehumidification. Many Floridians say they’ve never used a dehumidifier before, so dehumidifier options in local stores there may be limited.

If you live somewhere like Florida, you’ll have a better chance at finding energy-efficient, high-performance dehumidifiers for mold control online.

3. Measure the Space

This should be a breeze, and you probably even know this already.

Just like with buying an AC, your dehumidifier should match the size of the room. A desk dehumidifier that costs less than $100 on Amazon, for example, can’t do much for a 500 square-foot basement.

Ideally, the size and power of the dehumidifier must be directly proportional to the size of the space.

4. Assess the Space and Drainage Options

Examine the spot where you intend to install the dehumidifier. Is it in an unfinished basement or crawl space? Then you’ll need a robust unit designed for rugged locations.

Is there a drain nearby? Will you have to drain upwards? How about clearance? What’s the minimum size that can fit through the entrance of your crawl space? Take note of these details so you can have a reference when you’re looking at specs.

5. Decide Which Type of Dehumidifier to buy

To narrow down your options, consider the type that is best for your house.

• Portable dehumidifiers – Light and often wheeled, these are ideal for small to medium spaces.
• Whole-house systems – Powerful, ducted, and integrated into HVAC systems, these are designed to dehumidify multiple rooms in small to large houses.
• Desiccant models – Extracts moisture from the air using a rotating wheel covered in silica gel. These dehumidifiers are ideal for cold climates.
• Refrigerant models – Extracts moisture from the air through condensation, with the aid of an intake fan and a cooling system. These dehumidifiers are best for warm climates.
• Dehumidifiers with pumps – Designed for continuous drainage in basements or low-lying areas, these dehumidifiers send the condensate through a drain tube instead of collecting the liquid in a tank.
• Dehumidifiers without pumps or tanks – Also designed for continuous drainage, these dehumidifiers must be elevated since they rely on gravity to drain condensate via a drainage tube.

Once you’ve completed this checklist, it will be easier to look for the right dehumidifier for your home.

Choosing the Right Dehumidifier for Your Home

Here are the things to consider when shopping for a dehumidifier for mold and moisture-related issues.

1. Capacity

Expressed as PPD or pints per day, the capacity indicates how much water vapor a dehumidifier can extract per day. If you look at specification sheets, the capacity will be expressed in “AHAM” or “At Saturation.”

• AHAM
  Pints collected at 80°F (26.7°C) and 60% relative humidity (RH). These are the baseline conditions set by the Association of Home Appliance Manufacturers and used for testing dehumidifier efficiency.
• Saturation
  Pints collected at 90°F (32.3°C) and 90-100% RH. This is an extreme and unlikely scenario, but it's necessary to gauge a dehumidifier's capacity. It indicates how capable it can be in tough situations, like during the hottest and most humid summer days.

Small dehumidifiers can remove around 30-75 PPD at AHAM. Bigger, heavy-duty dehumidifiers designed for large spaces like crawl spaces of large houses, warehouses, and multi-parking garages can remove up to 120 PPD.

Check out this buying guide based on capacity that keep the RH below 60%, which the U.S. Environmental Protection Agency (EPA) recommends for preventing mold. Energy Star provides on its website:

Runtime also matters as much as capacity. If you need a dehumidifier for mold growth prevention, choose one that can operate as long as necessary.

This begs the question: how often should dehumidifiers run? It depends on the need, which can change by the day. You may have to turn a dehumidifier on all afternoon in summer, then gradually reduce the hours as the season transitions to fall.

2. Tank Size

Most dehumidifiers with condensate tanks must be emptied regularly, manually. They shouldn’t be allowed to overflow to prevent electrical damage and ensure it continues to work efficiently.

So, how often do dehumidifiers need to be emptied?

It depends on the efficiency and tank capacity. For example, a 70 PPD dehumidifier with a half-gallon tank would have to be emptied more frequently than a model with a full-gallon tank.

Similarly, a 35 PPD dehumidifier with a 1.75-gallon tank may fill up at roughly the same time as a 120 PPD unit with just a one-gallon tank.

Besides thinking about how often you’ll have to pour the contents of a condensate tank, also consider where you’ll put the dehumidifier. If it’s for your bedroom or office, a 1L tank will be enough.

But if you need it for a damp basement or any room you don’t enter often, go for the unit with the biggest condensate tank.

For crawl spaces, manual-drain dehumidifiers are not an option. Your money will be better spent on a 70- or 145-pint dehumidifier with continuous drainage.

3. Drainage Options

If you find yourself asking, where should I place my dehumidifier? The answer almost always has something to do with drainage options. Here’s why.

As discussed above, dehumidifiers drain condensate in three ways:

• Collected in a tank, to be poured out manually
• Continuous drainage through a tube via gravity
• Add a vapor barrier – Lay a thick plastic sheet across the ground to stop moisture from rising through the soil. Overlap the seams and secure them tightly.

Manual drainage is only ideal for dehumidifiers in bedrooms, bathrooms, and living spaces, and only if you can commit to regularly checking if the tank is nearly full. Otherwise, you’re better off with a continuously draining dehumidifier.

The advantage with the latter two is you can turn on the dehumidifier and forget about it for hours, even days, unless you must change the settings. As such, gravity and pump drains are best for crawl spaces and basements.

4. Noise

Dehumidifiers typically make around 40-65 decibels (dBA) of sound. Refrigerant dehumidifiers make the most noise because they have compressors that circulate the refrigerant through the cooling coils when you turn on the unit.

But you don’t have to worry about dehumidifiers being too loud. According to the Bureau of Transportation Statistics, 40 dBA is like a quiet library, and 60dBA is the same volume as a normal conversation. Dehumidifiers will never be completely quiet, but the hum won’t be so disturbing as to interrupt your sleep.

5. Filter

“Does a dehumidifier clean the air?”

It’s one of the most frequently asked questions about dehumidifiers. The technical answer is yes, because it does have a filter, but only to a small degree.

A filter is in place simply to keep dust, soot, pollen, and other particulates from clogging up the vents and cooling coils. The dehumidifier’s job is first and foremost to extract water vapor from the air; filtration is just a part of the process designed to make dehumidifiers more efficient at removing moisture from the air.

6. Design and Portability

It’s usually a good idea to pick a portable dehumidifier for mold prevention

It’s usually a good idea to pick a portable dehumidifier for mold prevention

Wheels and handles are major considerations if you’re looking for something portable that you can use anywhere on your property.

7. Maintenance Requirements

Dehumidifiers are generally low maintenance.

Filters need changing once every three months, but if you don’t use the unit daily, the filter can stay on for longer. The vents should be unobstructed, and if you follow the recommended minimum clearance for the unit (i.e., at least one foot away from the nearest wall).

You must also keep other variables like stacks of boxes or piles of dirt; there should be no issue with air movement in and out of the unit.

8. Price

Quality dehumidifiers don’t come cheap.

Watson of Technology Connections says, “For [dehumidifiers] to be any good at all, it needs to cost more than $100.” Anything cheaper would be too small to make an impact in a damp room. So instead of spending money on several cheap models, it’s wiser to invest in one energy-efficient and highly effective dehumidifier for mold control.

Also, keep an eye out for ENERGY Star certifications. A higher priced unit that’s Energy Star rated, for example, can save you more money in the long run than a cheaper yet inefficient model that uses more power.

9. Warranty

Manufacturers offer warranties guaranteeing free repairs, free replacements, and other benefits in case a dehumidifier malfunctions within the warranty period.

Here at Argendon, we offer a five-year warranty that covers unit replacement and shipping costs (terms and conditions apply). Other brands offer one to three-year warranties. Needless to say, go for dehumidifiers with longer and more comprehensive warranties.

10. Other Features

If you still have trouble choosing after eliminating options based on the first nine criteria, look at the rest of the product specifications.

“Today’s market offers dehumidifiers with fascinating upgrades like built-in hygrometers, auto shut-off, and continuous drainage options, making them more user-friendly than ever,” Josh Mitchell, HVAC specialist and founder of the HVAC online info hub, AirConditionerLab, said to BobVilla. “I’d say, look for models with Energy Star ratings for efficiency.”

Smart features like auto-defrosting and auto-drainage are also useful because they keep the dehumidifier running with minimal intervention.

Bonus Section: What’s better for mold control, dehumidifier or air purifier?

"Dehumidifiers are essential tools to lower the relative humidity, whereas air purifiers capture and remove airborne particles," said associate professor Weining Wang of Virginia Commonwealth University’s Department of Mechanical and Nuclear Engineering, in an interview with LiveScience.

Air purifiers with high-efficiency particulate air (HEPA) filters can remove up to 99.97% of airborne particles, including mold spores. However, just like dehumidifiers, air purifiers cannot remove mold that has already taken root. No matter how long you run an air purifier, the mold on the walls will stay there until a remediation expert removes it.

Dehumidifiers, however, are better at keeping mold from spreading or returning, as already discussed above. So, if you’re choosing between an air purifier or dehumidifier for mold prevention, we recommend the latter.

Dehumidifiers Are Your Best Tools for Controlling Mold and Moisture

"Choosing the right dehumidifier for mold and moisture control comes down to knowing your space, your climate, and your comfort needs. After all, it’s not just a household appliance but an investment for your household’s comfort, health, and protection for everything you value at home.

Don’t settle for guesswork—pick a dehumidifier that fits your lifestyle and climate. Pay attention to room size, dampness, and dehumidifier specifications like capacity, efficiency, drainage options, and other useful features discussed in this article.

The good news is you can start your search right here at Argendon.

Browse our shop for crawl space and basement dehumidifiers that you can also use in bedrooms, living spaces, commercial spaces, and even in rugged environments. You’ll find that our dehumidifiers are shoulder-to-shoulder with, if not at a better standing than other popular brands in the market.

Visit our Reviews page to see what other customers are saying about Argendon, and check out all dehumidifier models at our Shop.