If your basement feels humid, smells musty, or you notice signs of mold growth, installing a basement dehumidifier is a smart move. It helps reduce condensate, moisture levels, improve air quality, and protect your home from potential damage. The process is straightforward, but a few thoughtful decisions can make a big difference in how effective your dehumidifier is. Here’s how to get it right.

Choosing the Right Spot for Your Dehumidifier

Location matters when it comes to dehumidifier efficiency and optimal humidity levels. Keep these factors in mind when deciding where to place portable dehumidifiers:

  • Central placement: Position the dehumidifier centrally in the basement to maximize coverage. This allows the unit to draw excess moisture evenly from all parts of the space.
  • Keep it away from walls: Leave at least 6–12 inches of space around the dehumidifier, especially near the air intake and exhaust vents. This prevents airflow blockage.
  • Avoid obstacles: Keep the area clear of furniture, boxes, or anything that might obstruct the air circulation.

If your basement has specific problem areas, like corners prone to dampness, we'd suggest you prioritize those zones.

A basement living room with rolling cabinets and a dehumidifier.
Make your living spaces more tolerable with a dehumidifier. Credit: Andrea Rugg / Getty Images

Steps to Set Up Your Dehumidifier

Once you’ve chosen the right spot, setting up the dehumidifier is easy.

  1. Read the manual: Every dehumidifier is slightly different, so take a moment to check the instructions and installation tips specific to your model.
  2. Plug it in: Put the dehumidifier on a flat, stable surface and connect it to a grounded outlet. Avoid using extension cords; they can overheat.
  3. Adjust the settings: Most dehumidifiers allow you to set a target humidity level. For basements, 30–50% relative humidity is a comfortable level and a good range to aim for.
  4. Set up drainage: If your unit has a built-in pump and you have a basement drain and don’t want to empty the tank frequently, attach a garden hose to the gravity drain port and direct it to a floor drain or sump pit. Make sure the drain hose slopes downward for proper drainage and to prevent backflow.

Maintaining Your Dehumidifier for Best Results

Regular maintenance keeps your dehumidifier running efficiently and prolongs its life. Here’s what you should do:

  • Empty the tank: If you’re not using a self-draining unit, check the tank for water daily or every few days to avoid overflows. They usually have a shut off feature once the tank is full, but better to be safe than sorry.
  • Clean the filter: Most portable units have a washable air filter that should be cleaned monthly to maintain airflow and performance.
  • Inspect the hose: For units with continuous drainage, ensure the hose is securely attached and free of kinks or blockages. Also make sure the hose is still in your floor drain or directed to your sump pit.
  • Check for frost: If your basement is cold, look out for frost buildup on the coils, which can hinder performance. Many dehumidifiers have an automatic defrost function to address this issue.
A gray dehumidifier set up in a home basement.
How often do you clean your dehumidifier? Credit: Emily Fazio

Benefits of Installing a Dehumidifier

  • Reduced risk of mold and mildew growth
  • Protection for stored items, furniture, and walls from moisture damage
  • Improved air quality and reduced allergens
  • A more comfortable and usable basement space

FAQ

Do I need a dehumidifier in the winter?

It depends on your basement’s moisture levels. If your basement remains damp during the winter, running a portable dehumidifier is a good idea; if the air becomes dry, you can switch the unit off or adjust the ambient humidity level to avoid over-drying the space.

Dirty, dusty filter on a dehumidifier.
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How do I know what size dehumidifier to buy?

The unit size of the dehumidifier really depends on the square footage of your basement and its humidity level. Smaller units are suitable for spaces under 1,500 square feet with light moisture issues, while larger units can handle over 3,000 square feet or significant dampness. Check the unit’s capacity, typically measured in pints of water per day, to match your needs and to determine if you may need an additional unit to cover your entire basement.

Will the dehumidifier get rid of standing water?

In short, no. A dehumidifier is meant to remove water vapor from the air, not dry out puddles of water. If you have standing water, you'll need a wet vac or pump to deal with the water first. If you have ongoing issues you may need to consult a professional about basement waterproofing solutions. A dehumidifier can then help dry out the space by removing moisture from the air, walls, and furniture.