Why Your Shower Drain Smells (And How to Fix It)

A foul smell rising from your shower drain is unpleasant and often signals a fixable problem. Here are the most common causes and how to address each.

Biofilm buildup

The most common culprit is a slimy layer of bacteria, hair, soap scum, and skin cells coating the inside of the drain. This biofilm produces that musty, sour smell. Cleaning the drain thoroughly usually solves it.

A dry P-trap

The P-trap is the curved pipe that holds a little water to block sewer gases. In a rarely used shower, that water can evaporate, letting sewer smell in. Running water for a minute refills the trap and clears the odor.

Clogged or dirty drain

A partial clog traps decomposing debris. Removing the drain cover and clearing accumulated hair and gunk often eliminates the smell at the source.

Deeper sewer issues

If the smell is strongly like sewage and persists after cleaning, or if multiple drains smell, the issue may be a venting problem or a sewer-line fault — worth a professional inspection.

How to clean it

Remove the drain cover, clear visible debris, then flush with hot water. For a natural clean, pour baking soda followed by vinegar, let it fizz, and rinse with hot water. Avoid harsh chemical cleaners that damage pipes.