Last Updated on October 24, 2026 by Umar Farooq
Does a dehumidifier get rid of musty smell? Partly: it removes the dampness that makes the smell and stops it coming back, but it does not pull out an odour that has already soaked into fabric, carpet, wood or plaster. Whether it is the right tool depends on where the smell is actually coming from.
I like a machine that does one job properly, and this one does: it takes water out of the air. A smell is a different problem, and a dehumidifier is not a deodoriser, whatever the box implies.
Why damp air and a musty smell travel together
A musty smell is what you notice when something has stayed damp long enough for microbial growth to start on it. Energy Star describes a damp space with a musty smell as a sign of excess moisture, and says the optimum relative humidity (RH) for a building is generally 30-50%. EPA says the same range, adding that indoor humidity should stay below 60%, ideally between 30 and 50%.
So there are three separate things in play, and people tend to blur them:
| Thing | What it is | Does a dehumidifier change it? |
|---|---|---|
| The humidity | Water vapour in the room air | Yes, that is its whole job |
| The source | A wet wall, leak, damp pile or drain | No, it only slows the drying-out of the room |
| The odour in materials | Smell already absorbed into fabric, carpet, wood or plaster | Not directly; it can fade slowly once the item is dry, but often it does not |
The machine fixes the first row. The second row has to be fixed with a spanner, a bucket or a bin bag. The third row is why your jumper can still smell after a week in a dry room.
When a dehumidifier will fix the musty smell
Three situations are genuinely good news.
- The smell tracks the humidity. It is worse on muggy days or after a shower, and better in a dry week. A hygrometer reading above 60% in the smelly room is the confirmation, and bringing it to 30-50% usually takes the smell down with it.
- The cause was a one-off. A wet towel pile, a drying-rack winter, a flooded utility room that has since been mopped. Once the water is dealt with, a dehumidifier finishes the job on the air and the lightly affected surfaces.
- Nothing in the room is soaked. Hard surfaces such as tiles, painted walls and glass lose their smell once the air stops feeding it.
If your case sits here, the whole-house version of this is in how to lower humidity in a house, and the target number is explained in what indoor humidity should be.
Does a dehumidifier get rid of musty smell in carpet and fabric? Rarely
Here I will take a position: if the smell is still there once the room is dry, the item is the problem, not the room. Running the machine for another fortnight is the common mistake.
EPA is blunt about it: absorbent or porous materials, such as ceiling tiles and carpet, may have to be thrown away if they become moldy, because growth can get into the empty spaces and be impossible to remove completely. The same page says not to paint or caulk a moldy surface, so covering the smell with paint is also out.
In practice, that sorts into a rough order of hope:
- Washable fabric: a hot wash (as the label allows) and full drying. Good odds.
- Hard furniture: wipe, dry, and let it sit in dry air. Decent odds.
- Carpet and underlay: a dry surface can sit on a damp backing. If the smell returns, suspect the underlay or the floor beneath. Poor odds; my own judgement, not a measured figure.
- Plaster, wood and plasterboard that got properly wet: if the smell is in the wall, the wall is the source.
The honest summary is that a dehumidifier gives these materials the dry conditions they need to stop making new smell. Whether the old smell leaves depends on the material.
The order that works: source, air, item, number
Do it in this sequence, because the later steps are wasted if an earlier one is skipped.
If you find visible mould, wear gloves, eye protection and a well-fitting mask, and ventilate. EPA’s guide says most householders can handle a moldy area of less than about 10 square feet (roughly 1 square metre); for anything larger, use EPA’s remediation guidance or get qualified help. Never mix bleach with other cleaners.
- Find and stop the water. EPA’s first tip is to fix plumbing leaks and other water problems as soon as possible. If you cannot say where the damp is coming from, follow the smell to its source before buying anything.
- Dry the room. Run the dehumidifier with the doors and windows shut, internal doors open, and watch the hygrometer rather than the calendar.
- Clean or bin the smelly item. Wash it, wipe it or replace it, as the table above suggests.
- Hold 30-50% RH. Set the humidistat to about 50% and leave it there, because letting the room slide back above 60% invites the smell to return.
If the smell has no visible cause, the diagnosis routine is in musty smell but no visible mold. If it is confined to a wardrobe, mould in a wardrobe is the more useful read.
Where filters and odour products fit
A dehumidifier’s own filter catches dust. It is not an odour filter, so do not expect it to behave like one. Odour products (charcoal, sprays, ozone-type devices) are a separate question: they mask or adsorb the smell without addressing the moisture, so at best they are a bridge while you fix the cause. I am not recommending any of them here, and I would not buy one before steps 1 and 2 are done.
A dehumidifier fixes the cause of a musty smell, not the smell itself
That is the short version. If damp air is why the smell exists, a dehumidifier is the right tool and it will help. If the smell is in a carpet, a mattress or a wall, the machine can only stop it getting worse; the cure is cleaning or replacing the thing. Do it in order, hold the room at 30-50% RH, and the smell has nothing left to live on.
FAQ
How long does a dehumidifier take to remove a musty smell?
It depends on what is wet. Where the cause is humid air alone, I would expect the smell to ease over days as the reading falls, but I have no measured figure and the sources I read give none that I would trust. If the smell is unchanged after a week at 30-50% RH, the source is probably a material or a leak.
Will a dehumidifier kill mould?
No. It removes water vapour so mould stops getting what it needs to grow, but it does not clean existing growth. Visible mould has to be cleaned or removed as EPA’s guidance describes.
Does a dehumidifier help with smells that are not musty?
Not much. Cooking, smoke, pet or drain smells are not driven by humidity, so drying the air will not remove them. A dried-out drain trap, for example, needs water poured in, not a machine.
What humidity should I aim for to stop the smell returning?
Aim for 30-50% RH. EPA advises below 60%, ideally 30-50%, and Energy Star gives the same optimum range. A cheap hygrometer will tell you where you are.
Should I still run the dehumidifier after the smell has gone?
Yes, if the room tends to climb above 60% again. Let the humidistat do the work instead of running it flat out all day.
