A musty or stale smell from the steam is almost always stagnant water sitting somewhere in the generator or its pipework, not a fault with the steam function itself … the same reason a kettle left half-full for weeks smells off when you next use it. A metallic or burnt smell is a different, more serious problem: stop using the shower and see 'Why Does My Steam Shower Smell Like Burning' instead of this page.
Applies to: steam showers
INTRO HERE
Compatible with many shower cabin brands including
Quick diagnosis
If your steam shower is showing these symptoms:
- The steam smells musty or stale rather than clean
- The smell is worse the first time the shower's used after a few days
- Smell fades part way through a session
- A metallic or burnt smell rather than a musty one … a different, more urgent problem
- Steam seems to take a little longer to build than usual alongside the smell
Likely causes, most likely first
- Stagnant water in the generator. Steam generators hold a reservoir of water between uses; if it isn’t drained properly, that water sits and can develop a musty smell that carries through into the steam.
- The auto-drain function not working. Most generators drain themselves down after a session … you should hear this happen. If it isn’t draining, water sits in the tank until the next use.
- Limescale on the heating element. In hard water areas, scale builds up on the element the same way it does in a kettle; this reduces how well the generator heats and can eventually stop it working, but on its own it doesn’t explain a metallic or burnt smell.
Likely cause
Steam generators hold a reservoir of water and drain it down automatically after each use. A musty smell almost always means that water has sat for longer than it should, either because the generator hasn't been used for a few days or because the auto-drain isn't clearing the tank properly. Limescale on the heating element is the other thing worth checking in hard water areas, though that affects heating performance more than smell.
Check this first
- Listen for the auto-drain running after your next session … you should hear the generator draining down once the steam function is switched off.
- Note whether the smell is musty and stale, or metallic and burnt … a burnt smell isn’t something cleaning or descaling fixes, and needs different handling.
- Check whether the smell fades as the session goes on, which suggests it’s clearing residual stale water rather than a constant fault.
How to identify your part
The heating element sits inside the sealed generator body and isn’t something to open up and inspect casually. Run a couple of short steam cycles first to rule out stagnant water before assuming the element itself needs descaling.
How to fix it
- Run a full steam cycle and listen for the generator draining down afterwards … this is the auto-drain doing its job
- If it hasn’t been used for a few days, run a full cycle with a steam cleaning solution to flush stale water through the pipework
- If the generator isn’t draining down, reset the power to the unit first
- If it’s still not draining after a reset, the solenoid drain valve likely needs cleaning or replacing … this is inside the generator and best left to a qualified installer
- If you’re in a hard water area and haven’t fitted one, a water softener on the feed to the generator will slow future limescale build-up
Also described as
- Steam shower
- Steam shower cabin
- Hydro massage shower
When to call a professional
Never open the generator casing yourself … it's a mains-powered, plumbed-in unit. If the smell is metallic or burnt rather than musty, stop using the shower, isolate the power and call a qualified electrician or installer instead of descaling … see 'Why Does My Steam Shower Smell Like Burning'. If the drain valve is stuck or the element needs attention, isolate the power and call a qualified electrician or your installer.
