How to Get Rid of Musty Smell in Basement (For Good)

Quick answer: To get rid of musty smell in basement spaces, you have to remove the moisture that feeds mold and mildew, not just cover the odor. Find and fix the water source, clean or toss anything moldy, then run a dehumidifier set to 45–50% humidity. Most basements smell noticeably fresher within one to two weeks.

That damp, earthy basement smell is almost always a moisture problem in disguise. Candles and sprays mask it for an hour, then it’s back, because the source is still growing in the corners, boxes or carpet.

This guide walks you through how to get rid of musty smell in basement areas for good: how to find the source, what to clean with, how dry the air needs to be, and how to stop the smell from creeping back each summer.

What causes a musty smell in the basement?

The “musty” odor comes from microbial volatile organic compounds (MVOCs), gases released by mold and mildew as they grow. You can smell them long before you see any growth. Mold needs three things: moisture, a food source (wood, paper, dust, fabric) and time. Basements supply all three.

The most common sources are:

• High humidity. When relative humidity stays above about 60%, mold can grow on surfaces that never get visibly wet. The EPA recommends keeping indoor humidity between 30% and 50%.
• Condensation. Humid summer air hits cool concrete walls, cold-water pipes and ducts, and leaves moisture behind. This is why basements often smell worst in July, not in winter.
• Water seepage. Poor gutters, short downspouts and soil that slopes toward the house push water through foundation cracks. White, chalky deposits (efflorescence) on walls are a sign of this.
• Stored stuff. Cardboard boxes, old books, upholstered furniture and carpet pads soak up moisture and feed mold quietly for years.
• A dry floor drain or sump. If a floor drain trap dries out, sewer gas can rise into the room. That smell is sharper and more like rotten eggs, but it often mixes with mustiness.
• A damp crawl space. If your basement connects to a crawl space, humid air and odors travel between them. See our guide on how to get rid of humidity in crawl space.

Is a musty basement smell dangerous?

The smell itself is a warning sign, not a disease. But the mold behind it can trigger allergy-like symptoms, asthma flare-ups and irritation in sensitive people, according to the CDC. If anyone in the home has symptoms you think are linked to the basement, talk to a doctor, and treat the source quickly.

How to get rid of musty smell in basement: step by step

1. Measure the humidity first. Put a digital hygrometer in the middle of the basement for 24 hours. Above 60% RH means moisture is your main problem. Above 70% means mold is very likely growing somewhere. This single reading tells you how big a fix you need.
2. Find the source with your nose and a flashlight. Check corners, the bottom of walls, under stairs, behind paneling, around the sump pit, near the water heater and under any carpet. Lift a corner of carpet and sniff the pad. Look at the back and bottom of stored boxes and furniture. Dark spots, fuzzy growth, water stains and soft or peeling surfaces all point to the source.
3. Stop any water coming in. Clean gutters and extend downspouts at least 4–6 feet from the foundation. Regrade soil so it slopes away from the house. Fix plumbing leaks and insulate sweating cold-water pipes with foam sleeves. No cleaning step works for long if water keeps getting in.
4. Clear out and sort what’s stored. Throw away moldy cardboard, paper and anything soft that smells musty and can’t be washed. Move what you keep into lidded plastic bins and store them on shelves a few inches off the floor and away from exterior walls.
5. Clean hard surfaces. Scrub small patches of mold on concrete, block, metal and sealed wood with detergent and water, using a stiff brush. For stubborn spots on concrete, undiluted white vinegar left for an hour before scrubbing works on many common molds. The EPA does not recommend bleach as a routine mold killer, but a diluted bleach solution can be used on non-porous surfaces like concrete if you prefer. Dry every cleaned surface fully.
6. Deal with porous materials. Moldy drywall, ceiling tiles, insulation and carpet pad usually can’t be cleaned well enough and should be cut out and replaced. Wash fabrics you want to keep in hot water, or have them professionally cleaned.
7. Dry the air and keep it dry. Run a compressor dehumidifier set to 45–50% RH with a hose to a floor drain or sump, so it runs nonstop without a bucket. Keep basement windows closed in humid weather; outdoor summer air adds moisture. A box fan helps circulate air into corners during the first few days.
8. Refill traps and seal the sump. Pour a gallon of water into any floor drain you rarely use, plus a tablespoon of mineral oil to slow evaporation. Make sure the sump pit has a tight-fitting lid.
9. Absorb the leftover odor. Once the source is gone, set out open boxes of baking soda or bags of activated charcoal, and wash or replace musty rugs. Swap your HVAC filter, because it may have trapped odor-laden dust.
10. Check again in one to two weeks. Re-read the hygrometer and do another sniff test. The smell should be clearly weaker. If it isn’t, there’s a hidden source, often behind finished walls or under flooring.

Wear gloves, eye protection and an N95 mask when scrubbing mold or handling moldy materials, and keep kids and pets out of the area. Open the basement to fresh air or run a fan pointing outdoors while you clean. If you use bleach, dilute it per the label, use it only on non-porous surfaces, and never mix bleach with ammonia, vinegar or other acids, because it releases toxic gas. Rinse surfaces between products.

What doesn’t work (or makes things worse)

• Air fresheners and candles only cover the odor. The mold keeps growing.
• Ozone generators are sold as odor killers, but the EPA warns that ozone irritates the lungs and that these machines should not be used in occupied spaces. They also don’t fix the moisture.
• Painting over mold traps it. Clean and dry first; mold-resistant paint helps only on a clean, dry surface.
• Opening windows in summer. It feels like airing out, but humid outdoor air condenses on cool basement walls and makes things damper.
• Tiny thermoelectric dehumidifiers can’t keep up with a basement. They’re made for closets and small bathrooms.

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

If the source is surface mildew and humidity, most basements smell much better within a week of cleaning and running a dehumidifier. Full drying of concrete, wood framing and stored items can take two to four weeks. If you had water seepage or hidden mold behind walls, the smell will linger until those materials are removed.

The equipment that helps

A properly sized dehumidifier does most of the work. Add a hygrometer so you know it’s working. For more options and sizing help, see our full guide to the best dehumidifier for basement use.

The Waykar is the dehumidifier we point most people to first. Set it to 45–50%, run the hose to a drain and let it cycle. Read our Waykar 80-Pint review for setup tips.

Does an air purifier help with musty smell?

An air purifier with a thick activated carbon filter can help reduce lingering odors and some airborne mold spores once the source is fixed. It won’t dry the air, so it’s a finishing step, never the main fix. If odors come from pets as well, see our best air purifier for pet odor picks, which focus on carbon filtration.

How to keep the musty smell from coming back

• Keep humidity at 45–50% RH year-round, with the dehumidifier on a hose so it never stops because of a full bucket.
• Check the hygrometer weekly in summer. A creeping reading is your early warning.
• Clean gutters twice a year and keep downspout extensions in place.
• Insulate cold-water pipes and ducts that sweat in summer.
• Store in plastic, not cardboard, on shelves off the floor, with a few inches of space from walls.
• Vent the clothes dryer outdoors and avoid drying laundry on racks in the basement.
• Refill unused floor drains every month or two.
• Choose basement-friendly finishes: rigid foam insulation instead of fiberglass against concrete, and vinyl plank or tile instead of wall-to-wall carpet.
• Clean the dehumidifier filter every 2–4 weeks in humid months.

For the bigger picture on mold anywhere in the house, read our complete guide on how to get rid of mold and mildew. If the musty odor has spread upstairs, our guide to getting rid of bad smells in the house covers room-by-room fixes.

When to call a professional

Call a mold remediation company if mold covers more than about 10 square feet (the EPA’s guideline for DIY cleanup), if the smell remains after cleaning and a few weeks of dehumidifying, if mold is inside walls, ductwork or insulation, or if the basement flooded or had a sewage backup. Call a waterproofing contractor if water comes through walls or the floor after rain. Anyone with asthma, allergies or other health symptoms should avoid DIY mold cleanup and check with a doctor.

Frequently asked questions

Will a dehumidifier get rid of musty smell in a basement?

Yes, in most cases, because it removes the moisture that mold and mildew need. Set it to 45–50% humidity and run it continuously with a drain hose. It won’t remove existing mold or odors soaked into boxes and carpet, so clean or discard those too. Most basements smell clearly better within one to two weeks.

Does vinegar get rid of musty smell in a basement?

Undiluted white vinegar can kill many common household molds on hard surfaces like concrete and removes surface odor when you scrub with it. A bowl of vinegar left out absorbs very little. Vinegar helps with cleaning, but the smell returns unless you also lower the humidity and remove moldy porous materials.

Why does my basement smell musty only in summer?

Warm summer air holds more moisture. When it drifts into a cool basement, it hits walls, floors and pipes that are below its dew point, and water condenses. Humidity climbs above 60%, and mold starts releasing odor. Keeping windows closed and running a dehumidifier through summer usually solves it.

What absorbs musty smells naturally?

Baking soda, activated charcoal and fresh kitty litter all absorb some odors in a small space. They’re useful as a finishing touch once the moisture and mold are gone. On their own, they can’t keep up with a damp basement, because the source keeps producing new odor every day.

How do I get the musty smell out of things stored in my basement?

Wash fabrics in hot water with detergent and dry them fully in a dryer or in sunlight. Wipe hard items with a damp cloth and detergent, then air them out in a dry room. Cardboard, paper and upholstered items that stay musty after drying usually need to be thrown away, since mold can grow deep inside them.

Can a musty basement smell come from the HVAC system?

Yes. If your furnace or air handler sits in the basement, it can pull musty air and spread it through the house. Replace the filter, check the condensate drain pan for standing water, and fix the basement humidity. If the smell is strongest at vents, have an HVAC technician inspect the ducts for mold.

The fastest win is the right dehumidifier. Compare our top picks by basement size in the best dehumidifier for basement guide.