Why does my sink or shower drain smell?

A sink or shower drain can smell because debris is decaying near the outlet, water is stagnant, the trap has dried out or lost its water seal, or the drainage and appliance-waste arrangement has a fault. First establish whether the smell is in the water or around the plughole.

DWI recommends filling a glass and taking it into another room. If a rotten or stagnant smell disappears away from the sink, the drain is the likely source. If the water itself still smells strongly, check other taps and contact the water company.

For a little-used outlet, run water to restore the trap seal. Clean removable strainers and accessible surfaces using the fitting maker's instructions. Do not mix drain-cleaning chemicals or dismantle a trap when it serves equipment you do not understand; a bucket is also essential because the trap contains water.

Persistent smells, gurgling, slow drainage or smells affecting several outlets justify a drainage plumber. Approved Document H requires foul-water drainage to carry waste to an appropriate system, and a failed seal or vent should be corrected rather than masked with fragrance.

Appliance connections can change the pattern. Note whether the smell appears after a washing machine or dishwasher drains, and check the appliance manual for its required waste-hose route without disconnecting anything while it is running. In a flat, a shared stack fault may affect more than one home, so tell the managing agent. A strong smell with sewage backing up, an overflowing outside drain or several unusable fixtures needs urgent drainage help and careful hygiene.

Keep children and pets away from any backed-up waste water until the area has been cleaned safely.

Sources

• Taste and odour in drinking water — Drinking Water Inspectorate, accessed 14 November 2026.
• Approved Document H — GOV.UK, accessed 14 November 2026.

On Leatmere

Read drain smells and the glossary entry for a trap.