A musty basement isn’t just unpleasant—it can be a sign of bigger moisture problems that lead to mold and mildew growth. Whether your basement smells like an old book or a damp cave, eliminating the odor requires tackling the root cause. The good news? You don’t need harsh chemicals to freshen things up.

What causes your basement to smell, anyway?

Basements are naturally prone to humidity and poor air circulation, creating the perfect environment for musty, unpleasant odors.

  • Moisture buildup: Whether from leaks, condensation, or groundwater seepage, excess moisture is the main cause of mildew odors.
  • Mold and mildew growth: These fungi thrive in damp spaces and release spores that contribute to the musty smell.
  • Poor ventilation: Stagnant air allows odors to linger rather than dissipate.
  • Absorbent materials: Carpets, cardboard boxes, wood, and fabric can trap moisture and odors.
  • Drain and sump pump issues: Unmaintained drains and sump pits can develop bacteria and mold growth, producing foul odors.
French drain in concrete floor.
French drains are common in both basements and garages with concrete floors, but they can back up and cause smells. Credit: BanksPhoto / Getty Images

What Works, What Doesn't

After you've waterproofed and fixed leaks, a deep cleaning will eliminate bacteria, mold, and mildew spores. Be careful with bleach, it can damage fabrics and porous surfaces. 

The most effective strategy is to put dehumidifiers in place to continue to combat moisture levels and add fans to keep the air circulating. 

Natural odor absorbers like baking soda, vinegar, and charcoal can neutralize odors rather than masking a smell like air fresheners do. 

Storing fabric and paper materials in plastic bins rather than cardboard are the better way to store things in a damp environment.

Man is patching and painting a basement wall.
Patching and sealing the basement walls reduces moisture seepage which, in turn, helps manage musty odors. Credit: Yagi Studio / Getty Images

How to Remove Musty Odors and Mildew Smells From the Basement

You’ll Need:

  • Dehumidifier or fans
  • Baking soda
  • White vinegar
  • Activated charcoal or odor-absorbing packs
  • Scrub brush or sponge
  • Mold and mildew cleaner
  • HEPA vacuum (optional)
  • Plastic storage bins (optional)

1. Identify and Fix Moisture Sources

  • Inspect the basement for signs of water leaks in walls, floors, or pipes.
  • Check for condensation on window frames and pipes—insulate them if necessary.
  • Make sure sump pumps, sink drains, and floor drains are functioning properly and not holding stagnant water.

2. Increase Airflow and Reduce Humidity

  • Run a dehumidifier to keep humidity below 50%.
  • Open basement windows or use fans to increase air movement.
  • Install ventilation systems. (If moisture is a persistent issue, it's worth the investment).

A basement living room with rolling cabinets and a dehumidifier.
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3. Deep Clean Surfaces

  • Wipe down walls, floors, and storage areas with a mold and mildew cleaner or a vinegar-water solution.
  • Use a scrub brush to remove any visible mold or mildew stains.
  • HEPA vacuum carpets or consider replacing them with non-absorbent flooring.

4. Absorb and Neutralize Odors

  • Sprinkle baking soda on floors and leave it for several hours before vacuuming. Yes, this really helps.
  • Place bowls of vinegar or activated charcoal around the basement to absorb lingering bad smells. Dishes of coffee grounds is a good alternative, if you make a daily brew!
  • Swap out musty-smelling materials, such as old carpets, fabric furniture, or cardboard storage boxes. They cling to smells!

5. Maintain a Fresh Basement

  • Keep up with regular cleaning. If you have shelves or basement living areas, remember to dust, too.
  • Store items in sealed plastic bins rather than cardboard.
  • Check for leaks and moisture buildup periodically.
  • Run a dehumidifier in humid months to prevent future odors.
Dehumidifier installed on a window ledge in a humid house.
Dehumidifiers prevent excessive moisture in the basement that can contribute to mold, especially where moisture gathers around windows. Credit: Kateryna Artsybasheva / Getty Images

FAQ

How long does it take to get rid of a musty basement odors?

Eh, well, it depends on the severity of the issue. If it’s just lingering odors, freshening up the air and cleaning surfaces can improve things within a day or two. If you had a leaky pipe and water damage or significant mold growth, stale smells can take a week or longer to fully dissipate.

Can I use an air purifier to help with musty odors?

Yes! We use them throughout the house including in our basement. Air purifiers with HEPA filters and activated carbon can help remove mold spores and neutralize odors; however, they won't do much for moisture issues. Use alongside other solutions like basement dehumidifiers and cleaning for the best results.

How do I prevent my basement from getting musty in the future?

Keep your basement dry with dehumidifiers and good ventilation. Regular cleaning and using dehumidifiers or moisture absorbers can also help keep musty smells at bay. Severely damp basements may require installing a french drain to redirect water away from the foundation walls. If health issues or skin irritation persist, call a plumbing technician or a mold remediation company to address the problem.