The best dehumidifiers for mould and damp

Mould needs moisture. A dehumidifier is one way to take the moisture away, and it is the right tool when the damp is in the air: condensation on windows every morning, clothes drying indoors, a closed-up room that smells musty. It is the wrong tool for a leaking roof or rising damp. Prices below are from Bunnings and Appliances Online on 18 October 2026; for models also on Amazon Australia, check the current price on Amazon. We compared maker specifications and retailer listings; we have not tested these units, and we make no claim that any of them treats mould or any health condition.

Start with the water, not the machine

NSW Health’s fact sheet on mould lists the steps that reduce dampness, and most of them cost little:

• Turn on exhaust fans when showering, cooking, doing laundry and drying clothes.
• Open windows for cross ventilation when the weather allows.
• Limit unflued gas heaters, humidifiers, fish tanks and indoor plants.
• Repair leaks: burst pipes, a leaking roof, a blocked gutter.
• Rising or lateral damp in brick walls needs a building consultant, not an appliance.

It also says mould is likely to return unless the cause is treated. A dehumidifier fits in the “reduce humidity” part of that list. Clean the existing mould first (the fact sheet suggests four parts vinegar to one part water, or diluted bleach with gloves and eye protection for stubborn patches), then use the dehumidifier to keep the room dry.

How much capacity a mouldy room needs

More than a dry room does. Mould on a wall means water keeps arriving, from breathing, showers, cooking or the building itself, so the dehumidifier has to keep pace every day, not just once. Two other things cut real output below the box figure:

• Temperature. Ausclimate and Dimplex rate their compressor units at 30°C and 80% humidity. A mouldy room in autumn or winter is cooler than that, and a compressor pulls less water as the room cools.
• Tank stops. The units here that state it switch off when the tank is full. A 35 L unit with a 5 L tank needs emptying several times a day near its rating, so in practice it runs on a drain hose or it stops overnight.

Our guide: 10 to 12 litres for a wardrobe, laundry or bathroom; 20 to 35 litres for a damp bedroom or living area; 30 litres or more for a whole damp house, on a drain hose. Our rule of thumb for an unheated room that drops below about 10°C at night: look at a desiccant instead.

The Ausclimate 35L and Cool Seasons 10L and the Philips 3000 are also sold by Amazon AU; check the current price on Amazon.

The picks

The Ausclimate Large 35L is our pick for a damp room or a damp house: up to 35 litres a day at the stated 30°C and 80% humidity, continuous drainage, castor wheels on the Amazon listing, rated for rooms up to 50 m² at Bunnings, and $449. Of the dehumidifiers Bunnings sells itself rather than through Marketplace, it gave the most litres per dollar in our search.

For a cold room, the Ausclimate Cool Seasons 10L desiccant is the better tool even though its number is smaller. It is rated at 20°C and 60% humidity, closer to a winter bedroom, runs down to 1°C, and costs $388.50 at Bunnings ($488 at Appliances Online). Expect it to draw up to 730 W and add some warmth.

The Philips 3000 Series ($729) does 34.3 litres a day on a 258 W draw (Amazon listing) with humidity and temperature sensors that adjust it automatically. The Devanti 30L is the budget big unit at $237.95, but it is a Bunnings Marketplace listing with no test condition or power figure. The De’Longhi AriaDry Multi 25L adds Wi-Fi scheduling and a 5 L tank for $549, with a one-year warranty. For the dampest houses, the Mitsubishi Electric MJ-EV38HR reaches 38 litres a day with a 5.5 L tank, at $1,446.

For a general buying guide across all sizes, see the best dehumidifiers in Australia.

Where to put it

In the room with the problem, with its door shut while it runs, so it is drying that room and not the whole house. Keep it out from the wall so air reaches the intake, and put it near a floor waste, sink or outside door so the drain hose can run while you are out. Set the humidity control rather than running it flat out; once the room is dry, the unit should cycle off.

What an air purifier can and cannot do

People often ask whether an air purifier helps with mould. A purifier reduces airborne particles at its stated CADR; it does not remove water from the air or from walls, so it does nothing about the damp that lets mould grow. If you want one for the room as well, see the air purifier guide, but buy the dehumidifier first.

The one trap

Buying a “dehumidifier” that is sized by its tank. Amazon’s dehumidifier results are full of small units titled in millilitres (“2000ml”, “2500ml”); check whether that number is the tank or the daily capacity, because they are very different things. Bunnings lists one honestly: the AROVEC Compact has a 900 mL tank and removes 300 mL a day, for rooms up to 15 m². That is about a hundredth of the Ausclimate 35L’s rated capacity. For a mouldy room, look for a litres-per-day figure in the tens, measured by a compressor or desiccant, and the test condition beside it.