How to clean a dehumidifier: the filter, the tank and any mold, step by step

Do dehumidifiers need to be cleaned?

Yes. Every maker’s manual we checked asks you to clean the unit regularly. There are three practical reasons.

• Dust blocks the air. A dehumidifier pulls room air across cold coils. ENERGY STAR advises placing one away from dust and dirt, which can clog the coils and grilles. A clogged filter means less air, and less air means less water removed.
• Water sits inside it. The tank holds water from the room. The US EPA explains that mold starts to grow when spores land on a wet or damp spot. A tank that is left full or wet for days gives it that spot.
• Warranty. Stadler Form’s warranty, for example, excludes damage that results from a lack of cleaning.

In the UAE, dust is the bigger issue for most homes. Sand blown in from balconies, nearby construction and dusty days all end up on the filter.

Before you start: three safety rules

These come straight from the Stadler Form manuals for Albert, Lukas and Lukas Pro, and most other brands say the same.

1. Switch it off, then unplug it. Use the power button first, then pull the plug, not the cord.
2. Never put the unit in water and never pour water or any other liquid onto it or into the air inlet or outlet. There is a risk of a short circuit.
3. Do not open the housing. These models use R290, a flammable refrigerant. Stadler Form says repairs to the refrigeration system must only be done by the maker’s authorised technicians.

The manuals also say children should not clean the unit without supervision.

How to clean a dehumidifier, step by step

1. Empty the tank. Slide it out, pour the water away and look inside for slime, dark spots or a smell.
2. Clean the tank. The tank is a plastic container once it is out of the machine. Wash it with mild detergent and water, rinse it and let it dry fully. This is the same method the EPA gives for scrubbing mold off hard surfaces.
3. Take out the air filter or grille. On most units it sits behind the air inlet at the back.
4. Clean the filter. Albert’s manual says to remove the dust with a vacuum cleaner. Lukas and Lukas Pro say the inlet filter or grille can be removed and cleaned with a damp cloth. If you wipe it, let it dry before you put it back.
5. Clean the air inlet and outlet. Use a dry brush or the brush tool of a vacuum cleaner on the grilles, so dust does not build up on the parts behind them.
6. Wipe the outside with a damp cloth, then dry it.
7. Check the drain hose if you use one. It should not be kinked, and its end must be lower than the outlet on the unit, or water will not drain.
8. Refit everything dry, seat the tank properly, plug in and switch on.

If you use a hose for continuous drainage, read tank or drain hose: which suits the way you live.

A simple cleaning routine

The manuals say “regularly” rather than giving fixed intervals. This is the routine we suggest for a UAE home. Your own manual comes first if it says something different.

A room near a building site, a home with pets, or a ground-floor flat with a sandy balcony will need the filter checked more often than a closed bedroom.

Which filter does your model have?

Not every filter can be cleaned. A coarse dust filter can. The manuals say a HEPA filter cannot be cleaned and has to be replaced. Here is what the Stadler Form manuals say for the three models we recommend.

On a new Lukas Pro, the manual also says to take the HEPA filter out and remove its plastic film before first use. Arrows on top of the filter show which way it goes back in.

Stadler Form UAE lists the replacement HEPA H11 filters for Lukas and Lukas Pro at AED 199 each (price checked 4 November 2026). Albert has no HEPA filter, so its upkeep is the simplest of the three: a vacuum on the filter and a clean tank.

How to clean mold out of a dehumidifier, and stop the smell

Most smells come from the tank, not the machine. Water left standing in a warm room, or a tank put back while still wet, is the usual cause.

• Mold or slime in the tank: scrub it with detergent and water and dry it completely, as the EPA advises for hard surfaces. Empty the tank more often from then on, or switch to a drain hose.
• Musty smell from the air outlet: clean the filter and grilles first. If the smell stays, the room itself may be the source. A dehumidifier blows out the air of the room it sits in.
• Bleach: the EPA says a biocide such as chlorine bleach is not recommended as a routine part of mold cleanup. Never mix bleach with cleaners that contain ammonia, because toxic fumes can form.
• Mold you can see deep inside, on the coils: do not open the unit. Contact the maker’s service team.

Can I run vinegar through my dehumidifier?

No. A dehumidifier is not a kettle or a coffee machine. The manuals say never to pour any liquid onto the unit or into its vents. If you want to use a vinegar solution, use it only on the removed tank, then rinse and dry it. Detergent and water work for that too.

Storing a dehumidifier when you do not need it

In the UAE many people run a dehumidifier less in the cooler months, or move it between rooms. All three Stadler Form manuals give the same storage advice:

1. Empty the water tank.
2. Let the unit dry fully. If you are sending it for repair, Albert’s manual says to allow at least 24 hours.
3. Store it in its original carton.

Always carry it upright and empty the tank before moving it. After transport, Albert’s manual says to stand it upright and wait at least 60 minutes before switching it on.

Not sure when you can switch it off? See when to use a dehumidifier in Dubai.

Signs something is wrong after cleaning

If the unit still does not work well after a full clean, check these before calling for service.

• It collects little water. In a cool, air-conditioned room this can be normal. Albert’s manual says its rated output is only reached from about 22 °C and 70% humidity. Read what a 20 L/day rating means in an air-conditioned room.
• It shows defrost often. Albert’s manual says defrost runs more often at low room temperatures. Make sure an AC vent is not blowing straight at it.
• It leaks. Stadler Form’s advice for Lukas is to switch it off, check that the tank is seated correctly and that the hose is not kinked or running uphill, then clean the water outlet as the manual describes.
• It smells, gets loud or trips the power even when clean. Stop using it and contact the service team.

The Albert manual also asks for at least 50 cm of space around the unit, and says not to place it behind curtains. Blocked air looks like a dirty filter.

When the smell is the room, not the machine

A clean dehumidifier that still blows musty air usually means the room has a damp problem the unit is fighting. The EPA says a musty smell can point to hidden mold, and advises keeping indoor humidity below 60%, ideally 30 to 50%.

It is also worth checking your AC. The EPA advises keeping air conditioning drip pans clean and drain lines flowing. See why your AC smells musty.

If you cannot find the source, HawaQ’s mould testing service checks moisture room by room so you know what to fix.

Disclosure: HawaQ, the indoor air quality team behind this site, supplies Stadler Form dehumidifiers and MedicAir air purifiers in the UAE. How we recommend.

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