Why Does My Shower Drain Smell Like Sewage Even After Cleaning?
For a shower drain that gives off a sewage, rotten-egg or foul-drain smell even though the visible drain cover and shower tray have been cleaned.
What this usually means
A shower drain can smell like sewage even after surface cleaning because the odour source is often below the visible drain cover. A dry or poorly maintained water trap can let foul air through, biofilm and hair can remain deeper in the waste, and pressure problems can siphon water from the trap. Persistent odour combined with gurgling, slow drainage or smells at several fixtures can indicate a wider waste-pipe or ventilation problem rather than a dirty shower tray.
What may be causing this
The shower trap has lost its water seal
Clues: The shower is little used, the smell is strongest after a period away, or the odour improves quickly after running water.
What to do: Run enough water to refill the trap. If the seal repeatedly disappears, a drainage ventilation or siphonage problem may need investigation.
Hair, soap residue and biofilm remain below the drain cover
Clues: The smell is stale, sulphurous or worse after a warm shower, even though the tray and visible grate are clean.
What to do: Clean the removable trap cup or accessible waste parts according to the shower-waste instructions, physically removing hair and sludge rather than relying on repeated chemicals.
Pressure changes are siphoning water out of the trap
Clues: The shower gurgles when another fixture drains, or the smell returns after a toilet, bath or appliance empties.
What to do: A plumber can check branch pipework, ventilation and trap arrangement. Building guidance requires traps to retain a water seal under working conditions.
There is a deeper waste-pipe or drainage fault
Clues: Several fixtures smell, drainage is slow, wastewater backs up, or the odour seems to come from below the floor rather than the drain opening.
What to do: Stop treating it as a cleaning issue and have the waste system inspected for blockage, leaking joints or ventilation problems.
How to check what is happening
A dry or depleted water trap is a strong possibility.
Biofilm and trapped organic debris are likely contributing to the odour.
Pressure changes may be disturbing the trap seal.
The fault may be in shared drainage rather than the shower itself.
Can you fix this yourself?
Refilling a dry trap and cleaning a serviceable shower-waste insert are reasonable DIY steps. Repeated trap loss, gurgling with other fixtures, smells from multiple drains or inaccessible wastes under a shower tray need a plumber or drainage specialist.
- Rubber gloves
- Torch
- Old towels
- Shower-waste or trap instructions
- Small non-metallic cleaning brush if recommended by the manufacturer
What you can safely try
- 1
Refill the shower trap with clean water
Run the shower long enough to fully replenish the trap. If the shower has been unused for weeks and the smell then disappears, evaporation may have been the cause.
- 2
Clean the removable waste parts
Remove only the drain insert, hair catcher or trap cup designed for routine cleaning. Physically remove hair, soap film and sludge, then refit the parts correctly.
- 3
Do not keep adding different drain chemicals
Repeated or mixed chemicals can create dangerous reactions and may complicate later maintenance. If one has already been used, follow its safety instructions.
- 4
Check whether other fixtures trigger gurgling
Have someone empty a basin, bath or flush the toilet while you listen at the shower drain. Gurgling or visible movement in the trap is useful evidence of a pressure or ventilation issue.
- 5
Escalate a smell that keeps returning
If a clean, water-filled trap still allows foul odour through, a plumber should check the trap, branch waste, joints and ventilation rather than continuing to mask the smell.
Call a plumber if…
- Several fixtures are backing up or draining slowly.
- Wastewater rises into the shower tray.
- There is a visible leak below the tray or through a ceiling underneath.
- You have recently used incompatible or unknown drain chemicals.
- The smell is strong throughout the property rather than local to the shower.
Get the right professional.
This problem can have more than one cause. Start with the checks above: a plumber is the usual first route, while a drainage specialist may be more appropriate when the clues point that way.
Sources used for this guide
We prefer primary UK guidance, regulators and manufacturers for technical and safety-sensitive claims.
- Drainage and Waste Disposal: Approved Document HGOV.UK
- Section 1: Sanitary Pipework – TrapsMinistry of Housing, Communities and Local Government
- Drainage – Principles of Above Ground DrainageLondon Borough of Redbridge
Last reviewed: 31 August 2026. Home Manual updates review dates only when the substance of a guide is checked or changed.