Shower drain smells like mildew

Symptoms

• Musty, mildew-like smell near the shower drain
• Smell noticeable especially right after showering while the area is still damp
• No standing water or visible clog
• Smell may be accompanied by a slightly slower drain

Likely causes

• CommonMold or mildew growth inside the drain openingThe dark, damp, organic-rich environment inside a shower drain is ideal for mold growth.
• CommonSoap scum and hair buildup providing a food source for mildewEven without a full clog, this buildup supports odor-causing growth.
• PossiblePoor bathroom ventilation contributing to overall mustinessA humid bathroom can make any drain-related smell more noticeable.
• PossibleDry trap letting sewer gas through, mistaken for mildewWorth distinguishing the type of smell if it's more sulfur-like than musty.

What to do

1. Remove the drain cover and clean out any visible hair, soap scum, or slime with a brush.
2. Pour a baking soda and vinegar mixture down the drain, let sit 15–20 minutes, then flush with hot water.
3. Follow up with a diluted bleach solution (check it's safe for your pipe material) or a specialized drain-cleaning product to kill remaining mold if the smell persists, rinsing thoroughly afterward.
4. Improve bathroom ventilation by running a fan during and after showers to reduce ambient humidity.
5. Repeat the cleaning routine every few weeks as part of regular bathroom maintenance.
6. If the smell is more sulfur-like than musty, treat it as a possible dry trap issue instead and run water to refill the trap.

Tools and parts

• Brush
• Baking soda
• Vinegar

When to call a pro

Call a plumber if the smell persists after thorough cleaning, since it could point to a deeper clog or venting issue.

Safety