How to Get Rid of Dehumidifier Smell
A musty smell from a dehumidifier is, in most cases, caused by standing water in the tank, a dirty air filter, or moisture built up on the internal coil, not an actual fault in the unit. The first and most important fix is regular cleaning of the tank and filter, which solves the problem in most cases with no extra purchase needed.
The quick answer
A bad dehumidifier smell is mainly caused by standing water in the tank, a dirty filter, or moisture on the internal coil, not a fault in the unit. The first fix is cleaning: empty and wash the tank, clean the filter regularly, and let the unit air out after each use. If the smell persists after cleaning, dedicated tank cleaning tablets are a practical addition that helps dissolve buildup, but they complement cleaning rather than replace it.
Key points
- The unit continuously collects water from the air by design, which makes it an ideal environment for mold and bacteria to grow if it isn’t cleaned regularly (dehumidifier definition from ENERGY STAR).
- Standing water in the tank is the most common cause of the smell, especially if the unit was left for a long stretch with water inside it and never emptied.
- A filter dirty with dust and moisture together is an ideal environment for mold (background on mold growth from US EPA).
- Regular cleaning fixes the problem in most cases, with no need for any extra purchase.
- The smell isn’t a manufacturing flaw, it’s a natural result of built-up moisture and dust, like any appliance that collects water and air inside it.
The real cause behind the smell
A dehumidifier, by design, pulls in humid air and continuously collects the condensed water in a tank. That makes it an ideal environment for mold and bacteria to grow if it isn’t cleaned regularly. The most common causes of the smell:
- Standing water in the tank for a long stretch, especially if the unit was switched off with water still inside it.
- A dirty air filter collecting dust and moisture together, an ideal combination for mold growth.
- Moisture built up on the internal coil if the unit runs in a closed room without enough ventilation.
- A faint chemical smell on first use is normal in some new units and fades with time, but if it turns into a persistent musty smell, the cause is moisture buildup, not the unit itself.
Causes and quick fixes
| Cause | Sign | Fix |
|---|---|---|
| Standing water in the tank | Musty or damp smell, especially after a period of disuse | Empty, wash, and dry the tank regularly |
| Filter dirty with dust and moisture | Smell gets worse the more the unit runs | Wash or tap the filter clean per the manual |
| Moisture on the internal coil | A faint damp smell even with a clean tank | Wipe visible moisture and improve ventilation around the unit |
| Chemical smell on first use | A faint plastic smell that fades over time | Usually normal, keep an eye on it if it persists |
The fix: cleaning steps in order
- Unplug the unit before any cleaning step.
- Empty the tank and wash it with warm water and mild soap, rinse well, and let it dry completely before reinstalling it.
- Remove the air filter and wash or tap it clean per your model’s manual, let it dry fully before putting it back, and if it’s old or torn, replace it.
- Wipe any visible moisture on the internal coil with a cloth from the outside only, without opening up the unit’s internals yourself.
- Let the unit air out somewhere well ventilated instead of a fully closed corner all the time.
- Repeat this cleaning on a regular schedule (weekly, or per your model’s manual), not only once the smell shows up.
This routine fixes the problem in most cases with no need to buy anything extra.
What if the smell persists after cleaning?
If you’ve cleaned the unit with the steps above and a faint smell still lingers, there’s a practical addition that can help: dedicated tank cleaning tablets dissolve mineral deposits and the biofilm buildup inside the tank more easily than water and soap alone. This addition complements cleaning, it doesn’t replace it, so if your tank or filter is already genuinely dirty, tablets alone won’t fix the root problem. Check your model’s manual first to see if it supports this kind of cleaning, and if a strong smell persists despite regular cleaning, that’s a sign it may be time to inspect the unit or replace it.
A working example from our picks
If you’ve decided your current unit genuinely needs replacing, a practical criterion worth looking for is a tank and filter that come apart easily for cleaning. An example from our shortlist: the Pro Breeze 20L/Day Dehumidifier (≈ 849 AED), with a tank and filter that come apart easily for regular cleaning, which is why it tops our guide to the best dehumidifier in the UAE. Regular cleaning with the same steps above keeps its lifespan and smell in check just like any other unit.
See the Pro Breeze 20L/Day Dehumidifier price on Amazon.ae ↗
Bottom line
A bad dehumidifier smell is, in most cases, caused by standing water in the tank, a dirty filter, or moisture built up on the internal coil, not an actual fault. Regular cleaning (tank, filter, ventilation) fixes it in most cases with no extra purchase needed, and tank cleaning tablets, if your model supports them, are a practical addition, not a substitute for cleaning. If you want to understand where all this moisture in your home comes from in the first place, see why is my house so humid in the UAE, and if your issue is actually mold on walls or in closets rather than the unit’s own smell, read how to prevent mold in an apartment. If your old unit genuinely needs replacing, head back to our guide to the best dehumidifier in the UAE or our guide on how to choose a dehumidifier, and browse the full dehumidifiers category.
Sources
- ENERGY STAR, “Dehumidifiers”, definition of the dehumidifier and its internal parts like the tank, filter, and coil: https://www.energystar.gov/products/dehumidifiers
- US EPA, “Mold, moisture and your home”, background on mold growth in enclosed, humid environments: https://www.epa.gov/mold/brief-guide-mold-moisture-and-your-home
📊 This analysis is based on buyer reviews from ENERGY STAR (Dehumidifiers), US EPA (Mold, moisture and your home).
Frequently asked questions
Why does my dehumidifier smell musty even though it seems to work fine?
Because the smell usually has nothing to do with a fault in the motor or compressor. A dehumidifier continuously pulls water vapor from the air and collects it in an internal tank, and if that water sits stagnant for a while, or dust builds up on the air filter alongside moisture, that's an ideal environment for the mold and bacteria that cause the smell. Regular cleaning of the tank and filter fixes it in most cases.
How exactly do I clean the water tank and filter?
Unplug the unit first. Empty the tank and wash it with warm water and mild soap, rinse well, and let it dry completely before reinstalling it. Remove the air filter and wash or tap it clean per your model's manual, let it dry fully too before putting it back, and if the filter is old or torn, it's time to replace it. Wipe any visible moisture on the internal coil with a cloth from the outside only, and let the unit air out somewhere well ventilated instead of a fully closed corner.
Do tank cleaning tablets actually help remove the smell?
They help as a practical addition after manual cleaning, not a substitute for it. Some tank cleaning tablets made for household appliances that collect water dissolve mineral deposits and the biofilm layer inside the tank more easily than scrubbing with water alone. But if your tank or filter is already genuinely dirty, tablets alone won't fix the root cause, so always start with the basic cleaning routine first.
How do I prevent the smell in the first place?
Don't leave standing water in the tank if you won't use the unit for a while, empty, clean, and dry the tank before storing it, clean the filter regularly per your model's manual, and leave enough space around the unit for airflow instead of running it wedged into a fully closed corner.
Is a faint smell on first use normal?
Yes, usually. A faint plastic smell on first running is common in many new units and fades with time. But if it turns into a persistent musty smell or gets stronger with use, the cause is almost always moisture buildup in the tank or filter, not the unit itself, and cleaning it with the steps above fixes it.
This guide contains affiliate links: we may earn a commission when you buy through them, at no extra cost to you. Our picks are based on research, not payment. How we choose · Full disclosure.