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Can a dehumidifier help with mold? What it does and does not do

A dehumidifier controls humidity. It does not remove mold that is already there. Here is what EPA advises and where a dehumidifier fits.

Marvin SmitFounder & editorUpdated November 1, 20262 min read
How this guide was researched. We checked ENERGY STAR certification records, manufacturer documentation and US government guidance. We have not hands-on tested these dehumidifiers. Read our approach and affiliate disclosure.

What a dehumidifier can do

  • Below 30%Drier than the ideal range
  • 30–50%EPA's ideal range
  • 50–60%Still below 60%
  • Above 60%EPA advises lowering it
The humidity range EPA advises, drawn as a scale. Illustration only.

EPA puts it simply: the key to mold control is moisture control. A dehumidifier is one of the tools for that. It lowers the humidity in the air and keeps it at the level you set.

EPA advises keeping indoor humidity below 60 percent, and ideally between 30 and 50 percent. It lists air conditioners and dehumidifiers as ways to get there when needed.

What it cannot do

A dehumidifier can

  • Lower humidity in the air
  • Hold the level you set

It does not

  • Clean up existing mold
  • Fix a leak or seepage
  • Solve a large mold problem on its own
What a dehumidifier does, and what EPA says has to happen separately. Based on EPA's mold guidance.

A dehumidifier does not clean up mold that is already growing. EPA's advice is to clean up the mold and fix the water problem. It also says it is impossible to get rid of all mold and mold spores indoors, which is why controlling moisture matters.

EPA's guidance also says not to paint or caulk over moldy surfaces.

Size matters. EPA's home guidance covers small areas of mold, less than about 10 square feet. For larger areas, or after a lot of water damage, it points to its separate remediation guide. If you hire a contractor, EPA advises making sure they have experience cleaning up mold.

Fix the source of the moisture first

A practical order: stop the water, clean up, then keep the air dry. EPA's guidance covers each step.

Look for where the water comes from. Leaks, seepage, condensation on cold surfaces and water damage all add moisture. EPA notes that condensation can be a sign of high humidity.

After a leak or flood, EPA advises drying water-damaged areas and items within 24 to 48 hours to prevent mold growth.

Once the source is fixed, a dehumidifier helps keep the space in the humidity range EPA recommends.

If you decide to buy one

Recommended capacity, pints per day

Scroll sideways to compare room sizes.

ENERGY STAR recommended portable dehumidifier capacity in pints per day, by dampness and floor area.
Space without a dehumidifierUnder 2,000 sq ftOver 2,000 sq ft
Slightly to moderately damp50–75% humidity, musty at times20–3030+
Very damp75–90%, damp spots on walls or floor25–4040+
Wet90–100%, walls sweat or seepage30–5050+
ENERGY STAR's sizing chart, redrawn. Use it for any space where you plan to control humidity.

Size the unit for the space and how damp it is, using ENERGY STAR's chart. A basement with damp spots on the walls needs more capacity than a room that only feels damp.

Plan where the water will go, and check that the unit has a humidistat so you can hold a set level. Our basement guide covers sizing, pint ratings and drainage, and compares certified models.

No dehumidifier on its own makes a home mold-free. Treat it as part of moisture control, alongside fixing leaks and cleaning up mold.

Sources behind this guide

Our research connects an official source to a specific model, region and check date.

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