What Does a Dehumidifier Do?

Updated: Mar. 04, 2024

Dehumidifiers remove excess moisture from the air, preventing structural issues in your home and respiratory problems for you and your family.

Excessive humidity isn’t just uncomfortable. It can cause serious moisture-related issues in your home, along with aggravating allergy and asthma symptoms.

Considering these risks and not even being sure if a dehumidifier cools a room, a dehumidifier is a valuable investment for your home and family. As someone who grew up in the South and used dehumidifiers frequently, I know firsthand how effective they can be.

My family found ours to be especially useful in the laundry room. We air-dried a lot of clothing there, and it got extremely humid if we didn’t run the dehumidifier.

What Does a Dehumidifier Do?

A dehumidifier removes excess moisture from the air inside your home. It does this by drawing in air and running it past a cooling coil, which removes the moisture. The resulting water droplets collect in a drip tray.

According to Sanford Health, “Home dehumidifiers remove between 10 pints and 50 pints of water from the air each day.” Dehumidifiers typically power off when the air reaches the desired humidity level, and power back on to maintain that level.

Why Do I Need a Dehumidifier?

Not everyone needs a dehumidifier. If you live in a dry climate, you’re better off with a humidifier to add moisture to the air. For everyone else, a dehumidifier is definitely worth considering.

Important reasons to use a dehumidifier:

  • Mold prevention: Overly humid air can cause and accelerate mold growth in your home. Mold can cause respiratory issues, and removing it can be an expensive and time-consuming ordeal.
  • Preventing dry rot: Dry rot is a fungus that can weaken structural lumber supports. It’s extremely expensive to repair.
  • Allergy relief: If you have a dust mite allergy, a dehumidifier can make a big difference in your overall well-being and comfort. Dust mites feed on skin cells humans shed and thrive in humid environments. By reducing humidity, you’ll cut down on allergic reactions like sneezing and runny nose which can triggering asthma symptoms.
  • Odor control: By making mold and mildew growth less likely, dehumidifiers keep your home smelling fresh and clean.

Where Might I Need a Dehumidifier?

These common areas of the home may need a dehumidifier. If the excess humidity is due to poor ventilation or water leaks, fix those issues first.

  • Bathroom: Steamy showers and sinks raise the humidity in bathrooms, making them prone to issues like peeling wallpaper and mold. This is especially true if your bathroom lacks proper ventilation.
  • Basement: This is probably the most humid place in your home. Basements are typically poorly insulated and can be a source of groundwater leaks. Both conditions create humid air that can effect the rest of your home. Prevent moisture damage with the best basement dehumidifiers.
  • Attic: Roof leaks, improperly installed ventilation pipes and insufficient ventilation can make attics wet and humid. A dehumidifier can absorb that excess moisture and prevent expensive wood rot and other related problems.

P.S. If you have respiratory issues or live in a small space, these best small dehumidifiers are excellent options.

How Do I Know If I Need a Dehumidifier?

Because humidity itself is invisible, it can be a challenge to determine whether you need a dehumidifier. Look for these signs that could indicate high humidity levels in your home:

  • Do you have mold problems, or live in a climate prone to mold? Visual indicators like patches of dark mold on your ceiling or wall corners are an easy way to tell that your humidity levels are high.
  • Does your home have a musty odor? This smell is likely a result of the spores emitted by mold and mildew. If you don’t have any visual mold indicators, this smell likely indicates humidity levels above the recommended range.
  • Is the humidity level in your home above 50%?: According to Sanford Health, it should be between 30% and 50%. If it’s routinely higher than that, you’ll likely benefit from a dehumidifier. If you’re not sure, measure the humidity level with a humidistat. Also use a moisture meter to test any exposed lumber in your home; a reading above 15% indicates high moisture content.
  • Do you have peeling wallpaper? When humidity levels rise, the wallpaper adhesive may loosen. This can be a sign you need a dehumidifier.

Choosing the Right Dehumidifier

Consider these factors when purchasing a dehumidifier:

  • Capacity: The amount of water the unit holds will indicate how large a space the dehumidifier can handle. Knowing the square footage of the area you wish to dehumidify (multiply the length and width) will help you identify which models are large enough to work effectively. Energy Star also provides a helpful chart.
  • Size: Make sure your dehumidifier fits in your space. You’ll need to leave clearance on all sides for airflow (the distance varies by product).
  • Water storage method: Some dehumidifiers store collected water in a tank or pan that must be emptied. Others pump the water into a drain, sink or out the window. Pump dehumidifiers can be more convenient, but also more expensive.