Last Updated on October 25, 2026 by Umar Farooq
Why is my extractor fan dripping water? Almost always because warm, damp air is cooling inside the duct, turning back into liquid, and running downhill to the fan. The fan is usually innocent. The duct behind it is where the problem lives.
That drip landing on the bath, or on your head during a shower, is not a faulty motor. It is the same physics as a cold glass of water on a summer table, happening inside a tube you cannot see.
Rain, a leak or condensation? Read the timing first
Before touching anything, work out what kind of water it is. The timing gives it away.
| What you notice | Most likely cause |
|---|---|
| Drips start part-way through a shower or while cooking, and stop not long after the fan goes off | Condensation in the duct |
| Worse on cold, still mornings than on mild days | Condensation (the colder the duct, the more water) |
| Appears only during or just after heavy rain or strong wind | Water getting in at the outside cover |
| Drips with no link to using the room, and the ceiling around it is stained | A leak from the roof or a pipe, not the fan |
| Greasy, brown or smelly drips from a kitchen hood | Grease and condensation mixing in the filter and canopy |
The first two rows cover most cases, and they are the ones the rest of this guide deals with.
Why is my extractor fan dripping water? Because the duct is colder than the steam
A shower fills the bathroom with air that holds a lot of water vapour. The fan sends that air up a duct towards the outside. In winter the duct runs through a cold loft or a cold outside wall, so its inner surface is colder than the dew point of the air passing along it. Vapour condenses on that cold surface, the droplets join up, and they run in whichever direction the duct slopes.
If the duct rises towards the outside cap, gravity brings the water straight back to the fan. A manufacturer’s help page lists exactly this: warm, moist air cools towards the outdoor temperature, condenses and drips back down the duct, and flexible ducting and fans fitted without a downward slope make it worse.
Flexible ducting is the usual accomplice. Its ribbed, sagging walls make little pockets where water collects, then spills when the fan next starts.
Five fixes, in the order I would try them
Water and mains wiring do not mix. If water is dripping through the fan grille, switch the fan off at its isolator or the consumer unit before you touch it, and leave the cover on until it is dry. Anything involving wiring or removing a fixed fan is a job for a registered electrician, as Electrical Safety First advises.
- Clear the outside end. A blocked or stuck-shut outside cover traps humid air and slows the airflow, so more water condenses. Look from outside for a missing cover, a jammed flap, a nest or leaves. This costs nothing.
- Check the slope. The duct should fall slightly towards the outside, so water runs out instead of back. The Pacific Northwest National Laboratory’s Building America guide says the terminal should sit slightly below the fan so the duct slopes down and away from the housing.
- Insulate the cold stretch. Insulating the duct, especially where it crosses a cold loft, keeps its inner surface warmer than the dew point, so less water forms. The same guide says to insulate the duct to minimise condensation.
- Replace flexible duct with smooth rigid duct. The same guide prefers smooth rigid duct to flex, and says to keep the run short with few, gentle bends. Fewer pockets, less standing water.
- Fit a condensate trap or a damper if the run is long or vertical. A long, near-vertical run gives gravity too much to work with. A condensate trap catches the water before it reaches the fan, and a damper in the outside cap closes when the fan stops. A competent installer should fit both.
Do them in that order. The first three often solve it, and none needs more than a ladder and a roll of duct insulation.
Kitchen hoods drip for a different reason
A cooker hood is a slightly different animal. If it drips brown or greasy water, the culprit is grease: steam condenses on a filter that is already coated in cooking fat, and the mixture runs out of the canopy.
Wash or replace the filter following the maker’s instructions, then check the outside duct as above. If the water is clear and the duct is long, it is the same duct condensation story as in a bathroom.
When the drip is not the fan at all
Sometimes the fan is only the lowest point of a bigger problem. A drip that arrives regardless of whether anyone has showered, a stain spreading around the fan, or a smell of damp in the loft points to a leaking roof, a failed flashing or a pipe. Stop looking at the duct and call someone who can look at the roof.
If the ceiling around it is merely beaded with water after showers, the cause is steam reaching cold plasterboard. Bathroom ceiling condensation covers that and how to tell it from a leak, and why a fan can run and still leave the steam explains the airflow side.
A dripping extractor fan is a duct problem, so fix the duct and keep the fan
Replacing the fan is the expensive reflex. The new one will drip too if it is joined to the same uphill, uninsulated, ribbed duct. Clear the outside cover, make the duct fall to the outside, insulate it, and shorten or straighten it. Only when the run is long or vertical do you need a trap. If the loft end of the duct is the issue, venting a fan into the loft is the related trap to avoid.
FAQ
Is it normal for an extractor fan to drip water?
No, but it is common. A little condensation on the cover in a cold room after a long shower can happen, but water running or dripping from the grille means condensation is collecting in the duct and needs fixing.
Why does my extractor fan drip only in winter?
Because the duct is coldest then. The colder its inner surface, the more vapour turns to water, so the same shower that was harmless in July drips in January.
Can a dripping extractor fan cause mould?
Water repeatedly landing on the ceiling or around the fan keeps that spot damp, and mould needs damp. Fix the cause and dry the surface first; cleaning mould off without fixing the water only treats the symptom.
Can I stop an extractor fan dripping myself?
The first three fixes (outside cover, slope, insulation) are DIY if you can reach the duct safely. Anything touching the fan’s wiring, or fitting a trap or damper, should go to a registered electrician or ventilation installer.
Should the duct slope up or down?
Down and away from the fan, towards the outside. That way any condensation drains out of the building instead of back into the room.
