How to remove mildew smell from carpet

Step by step

1. 1

   Find the source of the damp

   Look for what's wetting the carpet: a leak, a spill or pet accident, a damp slab, condensation, a flood or high humidity. Press a dry paper towel on the carpet and pad in the smelliest area to feel for dampness.

   Why: Mold only grows where moisture lingers. If the source isn't fixed, the smell returns.

2. 2

   Protect yourself and vacuum

   Put on an N-95 respirator and gloves, then vacuum the area thoroughly and empty or throw out the vacuum bag outdoors.

   Why: Disturbing mildew releases spores. Vacuuming removes loose growth before you add any liquid.

3. 3

   Shampoo and extract

   Shampoo the carpet or use an extractor with a mild detergent, then pull out as much water as possible. Don't overwet.

   Why: Cleaning removes the growth and the soil it feeds on. Too much water reaches the backing and pad, feeding the very problem you're fixing.

4. 4

   Dry it fast

   Run fans and a dehumidifier, open windows if the air outside is dry, and lay a thick layer of white towels with a weight on top over damp spots. The carpet should be fully dry within 24 to 48 hours.

   Why: Mold usually won't grow on materials dried within that window.

5. 5

   Check the pad

   If the smell persists after drying, lift a corner of the carpet and look at the pad and floor underneath for dark spots, dampness or a stronger smell.

   Why: Mold often hides on the underside of carpet and pad, where surface cleaning never reaches.

6. 6

   Deodorize once dry

   When the carpet is completely dry, sprinkle baking soda over it, leave several hours or overnight, then vacuum.

   Why: Baking soda absorbs lingering odor. Put it on wet carpet and you just make a paste.

Why carpet smells musty

Carpet is a layered sponge: pile, backing, pad and sometimes a subfloor. Water from a spill, leak or damp slab can soak through to the pad, where it can't be blotted out and dries slowly. Mold grows there and gives off the musty compounds you smell. EPA notes mold can hide under carpet and pad, and that a moldy smell with no visible growth is a reason to look for it.

That's why the fix depends on how deep the moisture went. Surface mildew can be cleaned and dried. A pad that stays wet or moldy usually has to be replaced. See mildew smell for the general science.

When carpet or padding has to go

If mildew comes from moisture in the floor or the pad, the University of Florida's guidance is to remove the carpet and correct the moisture source. EPA says absorbent materials that stay moldy may need to be thrown away and replaced. After a flood, or if mold covers more than about 10 square feet, follow EPA's larger-scale cleanup guidance or hire a professional.

Visible mold spots on the pile itself are covered in mildew on carpet.

By situation

Musty smell in basement carpet

Basement slabs often wick moisture up from below. Run a dehumidifier to keep humidity under 60%, and check the pad. Carpet laid directly over a damp slab may keep smelling. See musty smell in a basement.

Carpet got wet from a leak or spill

Extract the water right away, run fans and a dehumidifier, and weight towels over the spot. Aim to have it dry within 24 to 48 hours.

Mildewed area rug

Vacuum it, shampoo it, and dry it quickly, outdoors in the sun if possible. If mildew remains, sponge with 1 cup rubbing or denatured alcohol mixed with 1 cup water after a colorfastness test, then dry thoroughly.

Musty smell but the carpet looks fine

Suspect hidden mold under the carpet or pad, or a moisture problem nearby. Check under the carpet and look for leaks, condensation or high humidity.

What not to do

• Don't cover the smell with carpet powder or spray. The musty smell means mold is growing. Masking it lets the growth continue.
• Don't overwet the carpet when cleaning. Water that reaches the backing and pad dries slowly and feeds mold.
• Don't leave wet carpet to dry on its own. If it stays damp beyond 24 to 48 hours, mold is likely.
• Don't mix chlorine bleach with ammonia or other cleaners. The combination releases toxic gas. EPA doesn't recommend routine bleach for mold cleanup anyway.

Other methods that work

Professional water-damage drying

After a flood or a large leak, restoration companies can lift carpet, dry the pad and subfloor, and replace what's ruined.

Caution: EPA points to professional remediation for mold over about 10 square feet.

Replacing the pad only

Sometimes the carpet can be cleaned and relaid over new padding once the floor is dry and the moisture is fixed.

Stain still there?

The smell came back a week after cleaning

The pad or subfloor is still damp, or the moisture source wasn't fixed. Lift the carpet to check, dry or replace the pad, and fix the leak or humidity.

It smells worse on humid days

Humidity is feeding residual growth. Keep indoor humidity below 60%, ideally 30 to 50%, with a dehumidifier.

Safety

• Wear an N-95 respirator, gloves and goggles without vent holes when cleaning moldy carpet, and avoid touching mold with bare hands.
• If mold covers more than about 10 square feet or came from flooding, use EPA's larger-scale guidance or a professional.

Never mix cleaning products; see chemicals you must never combine.

Questions

Mildew elsewhere

• Mildew: what causes it and how to remove it
• Mildew in a basement
• Mildew in a car
• Mildew in clothes
• Mildew in the house
• Mildew in towels
• Mildew in a washing machine

Other smells in carpet

• How to remove dog smell from carpet