This dehumidifier guide Australia answers the question directly: you need a dehumidifier if you have persistent condensation, musty smells or mould on walls and windows that ventilation alone won't fix. Aim to hold indoor humidity between 40 and 60 percent, and size the unit in litres per day to your room and dampness level.
Do you actually need a dehumidifier?
Not every home does. If your windows only fog on the odd cold morning and clear quickly, better ventilation usually solves it.
You likely do need one if you see foggy windows most mornings, black spotting in bathroom or bedroom corners, a lingering damp smell, or clothes that never quite dry indoors. These are signs moisture is outpacing your home's ability to shed it.
Mould thrives when humidity sits consistently above roughly 60 to 70 percent. Keeping a room reliably below 55 percent makes it far harder for mould spores to take hold and spread.
What causes damp and mould in Australian homes?
Everyday living pumps litres of water into the air. Showering, cooking, drying clothes indoors and even breathing all add moisture that has to go somewhere.
In coastal and northern regions, high outdoor humidity keeps homes damp much of the year. In southern states like Victoria and Tasmania, the problem spikes in winter, when we seal the house up and warm, moist air hits cold windows and walls, then condenses.
That's the difference between condensation and a genuine leak. A dehumidifier tackles moisture in the air, but it can't fix a roof leak, rising damp or a plumbing fault, so rule those out first.
How do you size a dehumidifier?
Dehumidifiers are rated by how much moisture they pull from the air in a day, measured in litres per day. Bigger rooms and damper homes need more capacity.
- Up to around 30m² (bedroom, single room): a unit up to about 20 L/day is usually enough.
- Open-plan living or moderately damp homes: look at 20 to 35 L/day.
- Large homes, basements or serious ongoing damp: choose 35 L/day or more.
When in doubt, size up. A slightly larger unit reaches your target humidity faster and then idles, rather than running flat out and struggling in a room that's too big for it.
Desiccant or compressor: which type suits you?
The two main technologies behave very differently, especially in the cold, and that matters a lot for a Southern-Australian winter.
You'll find both in a general home appliances range, so it pays to match the type to your climate before you buy.
| Feature | Compressor | Desiccant |
|---|---|---|
| How it works | Refrigeration, like a fridge | Absorbent drying material |
| Best temperature range | Works well above roughly 15 to 16°C | Works well in the cold, down to around 1°C |
| Cold-winter mould control | Struggles in unheated rooms | Excellent |
| Running cost | Generally cheaper to run | Uses more power per hour, but works faster |
| Bonus | Lower purchase price | Gives off a little warmth, runs quietly |
Which dehumidifier is right for your home?
If you're in a warmer or northern climate, or you'll run the unit in heated living areas, a compressor model is the economical, sensible pick.
If you're in a cooler southern state, or you're drying out an unheated bedroom, garage or basement where winter mould strikes hardest, a desiccant model is the safer choice because it keeps working when temperatures drop.
Whichever you choose, look for an adjustable humidity setting so it can target 50 to 55 percent and switch itself off once it gets there, plus a continuous-drain option if you'd rather not empty the tank daily.
How do you beat damp without relying on the machine?
A dehumidifier works best alongside good moisture habits. Cutting moisture at the source means the unit does less work and your bills stay lower.
- Run the exhaust fan during and for 15 to 20 minutes after every shower or cook.
- Open windows for 10 to 15 minutes daily, even in winter, to flush out moist air.
- Wipe condensation off windows and sills each morning before it feeds mould.
- Dry clothes outdoors or use a vented dryer rather than drying on racks in a closed room.
- Keep a stable indoor temperature so warm, moist air is less likely to condense on cold surfaces.
When you do tackle existing mould, protect yourself and your surfaces. A box of disposable Vileda Ansell WORKmates latex gloves keeps your hands clear of cleaning products and spores, and for fireplaces that add winter moisture and soot, a Scandia dry glass cleaner for fireplace glass clears baked-on grime without chemicals. Stock these alongside your other everyday household supplies so you're ready the moment damp appears.
Running costs and everyday maintenance
Before you commit, it helps to look past the purchase price at what a unit costs to run and keep going. As this dehumidifier guide Australia has stressed, sizing the machine correctly is the single biggest lever on your power bill, because a unit matched to the room reaches its target and idles instead of grinding away for hours on end.
Compressor models are generally the cheaper of the two to run per hour, which adds up over a damp winter of daily use. Desiccant units draw more power but work faster and in far colder rooms, so in an unheated southern bedroom they may actually run for less total time to hit the same result. Look for an in-built humidistat so the machine switches itself off at your target humidity, rather than running non-stop and wasting power once the air is already dry.
A little upkeep keeps performance high and the unit safe:
- Empty the tank promptly or plumb in the continuous-drain hose, since standing water can grow mould of its own and defeat the purpose.
- Rinse or vacuum the dust filter every couple of weeks, as a clogged filter makes the unit work harder for less result and drives running costs up.
- Keep clear airflow around the intake and outlet, leaving a gap from walls and curtains so the machine can breathe properly.
- Wipe the coils and housing occasionally on compressor models to stop dust building on the cold surfaces where it robs efficiency.
Position matters just as much as maintenance. A dehumidifier works best in a closed room with the doors and windows shut, placed centrally rather than jammed in a corner, so it can pull moisture evenly from the whole space instead of just the air right beside it. In a two-storey home, remember that damp air rises, so the upstairs rooms often need attention even when the problem seems to start below. If you only own one unit, move it to whichever room is showing the worst condensation that week rather than leaving it to run in an already-dry space.
The verdict on dehumidifiers
If damp, musty smells and mould are a recurring problem that airing out won't fix, a dehumidifier is a genuinely worthwhile buy. Size it to your room in litres per day, choose desiccant for cold rooms or compressor for warmer, heated spaces, and pair it with good ventilation to keep your home dry and healthy year-round.
Frequently asked questions
What humidity should I set my dehumidifier to?
Aim for 40 to 60 percent relative humidity, and target around 50 to 55 percent if mould is your main concern. Mould struggles to grow below 55 percent, so setting the unit there and letting it switch off once reached keeps your home comfortable without over-drying the air or wasting power.
Will a dehumidifier stop mould on my walls?
It stops new mould by keeping humidity too low for spores to grow, but it won't remove mould that's already there. Clean existing mould first, then run the dehumidifier to keep the room below about 55 percent. If mould keeps returning, check for leaks or rising damp, which a dehumidifier can't fix.
Do dehumidifiers use a lot of electricity in Australia?
Running costs depend on the type and how long it runs. Compressor models are generally cheaper per hour, while desiccant models draw more power but clear moisture faster, so they run for less time. Choosing a model with an adjustable humidity setting that switches off automatically keeps costs down.
What size dehumidifier do I need for a bedroom?
For a single bedroom or a room up to around 30 square metres, a unit rated up to about 20 litres per day is usually plenty. For open-plan or noticeably damp spaces, step up to 20 to 35 litres per day. When unsure, size up slightly so the unit reaches your target humidity quickly.
