How to Stop Window Condensation in a Rental

Renter-safe ways to reduce moisture, protect your windows and work out whether you actually need a dehumidifier.

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You wake up, pull back the curtains and find the inside of the window covered in water again. The glass is fogged, the sill is damp and the blinds or curtains may already smell slightly musty. You then ask how to Stop Window Condensation in a Rental?

In a rental, the problem is more frustrating because the obvious building fixes—replacing glazing, installing extraction, resealing frames or altering insulation—are usually not yours to make.

But you are not powerless.

Window condensation can be influenced by four things: the amount of moisture in the air, how cold the window surface becomes, how well the room is ventilated and whether there is a building defect such as a leak, failed seal or non-working exhaust fan.

The smartest renter-safe approach is to deal with the water immediately, measure the room’s humidity, reduce unnecessary moisture and only buy larger appliances when the evidence shows you need them.

The quick answer

To reduce window condensation in a rental:

1. Dry the glass and sill as soon as you notice water.
2. Use a digital hygrometer to measure indoor humidity.
3. Run bathroom and kitchen exhaust fans when producing steam.
4. Ventilate when the outdoor air is drier than the indoor air.
5. Avoid drying wet clothes in an unventilated room.
6. Use a fan to improve air movement, but remember that a fan does not remove moisture.
7. Use moisture absorbers only for small, enclosed spaces.
8. Consider a dehumidifier when humidity remains high or condensation returns quickly.
9. Document and report leaks, damaged seals or failed ventilation.

QUICK PRODUCT SOLUTION LINKS:

• Compare renter-friendly window vacuums.
• Shop compact digital hygrometers.
• Compare quiet portable circulation fans.
• Shop refillable wardrobe moisture absorbers.
• Compare portable dehumidifiers for bedrooms and apartments.

Why condensation forms on windows

Condensation forms when humid indoor air touches a surface cold enough for some of the water vapour in the air to become liquid.

Windows are often where you notice it first because glass and metal frames can become much colder than the surrounding room. Bedrooms are common problem areas because people add moisture to the air by breathing overnight, especially when the door and windows remain closed. Cooking, showering and drying clothes indoors add even more moisture.

That means a wet window does not automatically prove that the window is defective. It may be caused by indoor humidity, a cold surface, insufficient ventilation, a building issue or a combination of all four.

The key distinction is this:

• Drying the glass removes today’s water. Reducing moisture and improving ventilation addresses why it keeps returning.

1. Remove the water before it causes damage

Do not leave condensation sitting on the glass, frame or sill all day.

Use a clean microfibre cloth, squeegee or window vacuum to remove it. Check the corners of the frame, the bottom track and the back of curtains or blinds, where moisture can remain hidden.

A window vacuum is useful because it collects the water rather than pushing it across the sill. It can save time when you are drying several windows every morning.

However, it is important to understand what you are buying.

A window vacuum helps with:

• Fast daily clean-up
• Water sitting on glass and smooth window frames
• Reducing the time moisture remains against the sill

A window vacuum does not:

• Lower the room’s humidity
• Repair failed seals or leaks
• Stop condensation from returning

It is a maintenance tool, not a cure.

Recommended Upgrade: Compare renter-friendly window vacuums.

2. Measure the humidity before buying expensive equipment

The most useful first purchase is usually not a dehumidifier. It is a digital hygrometer.

A hygrometer measures relative humidity, shown as a percentage. It gives you an objective way to determine whether the room is consistently humid and whether your changes are working.

As a practical guide, aim to keep indoor humidity below 60% where possible. A range around 30–50% is commonly recommended, although the realistic level will depend on the climate, temperature and building. Use 60% as a warning line—not as proof that mould will or will not occur.

Do not panic over one reading. Relative humidity changes as temperature changes, so take readings in the same location over several mornings and evenings.

Record:

• The humidity percentage
• The room temperature
• Whether the window was wet
• Whether clothes were drying indoors
• Whether cooking or showering had recently occurred
• Whether an exhaust fan or air conditioner was running

After a week, you should have a much clearer picture.

Recommended Upgrade: Shop compact digital hygrometers.

3. Reduce moisture at the source

Before buying another appliance, identify where the moisture is coming from.

Drying clothes indoors

Wet laundry releases moisture into the room as it dries. When indoor drying is unavoidable, place the rack in the best-ventilated space available, keep it away from cold walls and windows, and use an exhaust fan, air-conditioner dry mode or dehumidifier where appropriate.

Avoid putting a full drying rack in a closed bedroom overnight. That creates the exact conditions that make morning window condensation worse.

Showering

Run the bathroom exhaust fan during the shower and leave it running afterwards. Keep the bathroom door closed while steam is being produced so moisture is not pushed into bedrooms and living areas.

If the exhaust fan does not work, report it rather than quietly accepting it.

Cooking

Use lids on pots and run the rangehood when boiling, steaming or frying.

Where the rangehood only recirculates air rather than venting outside, opening a nearby window or door may still be necessary when outside conditions allow.

Unflued gas heaters

An unflued gas heater releases water vapour and combustion pollutants directly into the room. Using one to “dry out” a damp room can make the moisture problem worse.

NSW Health warns that moisture from unflued gas heaters can build up indoors and contribute to conditions that support mould and dust mites. Follow the manufacturer’s ventilation instructions and never block permanent vents.

4. Improve ventilation intelligently

Opening a window can help, but “just open the windows” is incomplete advice—especially in humid Australian climates.

Ventilation works best when the outdoor air is drier than the indoor air. On a cool, dry morning, briefly opening windows on opposite sides of the home can release overnight moisture. During hot, humid or rainy weather, bringing more outdoor air inside may not reduce humidity.

Use the conditions, not habit, to decide:

• Cool and dry outside: open windows briefly and create cross-ventilation.
• Hot and humid outside: use exhaust fans, air-conditioning dry mode or a dehumidifier instead.
• Security prevents open windows overnight: ventilate in the morning and use mechanical dehumidification when needed.

Ventilation can reduce indoor humidity, but the right strategy depends on the climate, season and moisture direction.

Also check that furniture is not packed tightly against cold external walls. Leave a small gap behind wardrobes, bedheads and large drawers so air can circulate.

A portable fan can help move stagnant air away from cold corners, but it does not remove water from the room. Use it after drying wet surfaces or alongside ventilation, air-conditioning or dehumidification.

Recommended Upgrade: Compare quiet portable circulation fans.

5. Know when moisture absorbers are useful

Moisture-absorbing tubs, pouches and refillable containers can work—but only within their limits.

They are best suited to:

• Wardrobes
• Linen cupboards
• Under-sink cabinets
• Storage boxes
• Small enclosed spaces with mild dampness

They are not a realistic substitute for a proper dehumidifier in a damp bedroom, living room or open-plan apartment.

Independent CHOICE testing found that a common moisture absorber removed moisture far more slowly than even the weakest dehumidifier in its comparison. That does not make absorbers useless; it means they should be used for low-level dampness in smaller spaces, not room-wide moisture problems.

Always follow the product instructions and keep chemical absorbers away from children and pets.

Recommended Upgrade: Shop refillable wardrobe moisture absorbers.

6. When a dehumidifier is worth the money

A dehumidifier becomes worth considering when:

• Humidity repeatedly stays close to or above 60%
• Condensation returns soon after the windows are dried
• The room smells persistently damp or musty
• You regularly need to dry clothes indoors
• Ventilation and everyday habit changes have not solved the problem
• Moisture affects more than one window or room

A dehumidifier removes water from the air and collects it in a tank or sends it through a drain hose. Unlike a fan, it actually reduces the room’s moisture content.

What to compare before buying

Extraction performance

Do not choose a model based only on its appearance or tank size. Check the manufacturer’s rated extraction capacity and the conditions under which that rating was measured.

Performance can drop in colder rooms, so a unit that looks powerful on paper may remove much less water during winter.

Humidistat

A built-in humidistat lets you set a target humidity. The unit can then cycle on and off instead of running continuously after the room has reached the target.

Noise

Noise matters when the unit will run in a bedroom or study. Compare decibel ratings and customer feedback about the character of the sound, not just the headline number.

CHOICE notes that many dehumidifiers produce more than 50 decibels, which may be disruptive in sleeping or working spaces.

Tank and automatic shut-off

A larger tank needs emptying less often, but also makes the appliance heavier. Automatic shut-off is important so the unit stops when the tank is full.

Portability

Wheels, handles and manageable weight matter in a rental because one unit may need to move between a bedroom, bathroom and laundry area.

Continuous drainage

A drainage hose can be useful for long running periods, but only when there is a suitable and safe drain nearby.

Operating temperature

Refrigeration or compressor models generally perform better in warmer conditions, while desiccant models can retain more effectiveness in colder rooms.

Check the temperature of the space in which the unit will actually operate instead of buying solely from a headline litre-per-day figure. CHOICE advises that manufacturer extraction figures may be measured in warm, humid test conditions and that real winter performance can be lower.

Running costs

Check the wattage and estimate how many hours per day the unit will run.

A cheap machine that extracts very little water may be poor value when it has to operate constantly.

Recommended Upgrade: Compare portable dehumidifiers for bedrooms and apartments.

7. Check whether your air conditioner already has a dry mode

Before buying a separate appliance, inspect the remote for your existing split-system air conditioner.

Many systems include a dry or dehumidification mode. This can be useful during warm, humid weather because the air conditioner removes moisture while cooling the room mildly.

It is not always the best answer for winter condensation in a cold room, and it will only help the areas reached by that system. But when an air conditioner is already installed in the affected space, testing its dry mode may save you from buying another appliance.

Follow the manufacturer’s instructions and clean the filters regularly.

8. What not to do

Avoid these common mistakes:

• Do not rely on wiping alone while ignoring persistent high humidity.
• Do not assume every condensation problem is the tenant’s fault.
• Do not block wall vents to keep a room warmer.
• Do not push wardrobes and beds tightly against damp external walls.
• Do not expect one small moisture tub to dry an entire bedroom.
• Do not use unflued gas heating as a moisture-control strategy.
• Do not claim mould has been “fixed” while the moisture source remains.
• Do not repaint or seal over recurring mould without permission and without addressing the cause.

9. When to notify the property manager

Notify the property manager or owner when the problem appears to involve more than everyday surface condensation.

Warning signs include:

• Water entering around the window during rain
• A visibly damaged or separated window seal
• Peeling paint, swelling timber or soft plaster
• A bathroom or kitchen exhaust fan that does not work
• Mould returning rapidly after cleaning and drying
• Dampness appearing inside walls, ceilings or floors
• Condensation trapped inside double-glazed units rather than on the room-facing surface

Take dated photos and keep a simple record of humidity readings, weather conditions and when you reported the issue.

In Queensland, the Residential Tenancies Authority says responsibility for mould depends on what caused it. Tenants should notify the property manager or owner as soon as they become aware of the problem. When the cause is structural—such as leaking pipework or a leaking roof—the owner is responsible for addressing the mould and carrying out necessary repairs. Other states and territories have their own rules, so check the current tenancy authority for your location.

This article provides general information, not legal advice.

10. A simple renter-safe plan by budget

Lowest-cost starting point

Start with:

• A digital hygrometer
• Microfibre cloths or a squeegee
• Better use of existing exhaust fans
• Moving furniture slightly away from cold external walls

This stage tells you whether you have a minor morning problem or sustained indoor humidity.

Convenience upgrade

Add:

• A window vacuum for faster daily water removal
• A small portable fan for stagnant corners
• Moisture absorbers for wardrobes and cupboards only

This setup is suitable when the problem is localised and humidity is not persistently high.

Persistent-humidity setup

Use:

• A properly selected portable dehumidifier
• A hygrometer to verify the result
• Closed doors and windows while the dehumidifier is operating
• Exhaust fans at the moisture source

The dehumidifier should reduce the humidity reading and the amount of water returning to the windows.

If it does neither, you may be dealing with an undersized appliance, poor placement or a building issue that needs reporting.

FAQ (Frequently asked questions)

The real takeaway

Window condensation is not solved by buying the most expensive appliance first.

Start by removing the water. Then measure the humidity. Reduce moisture from cooking, showering and laundry. Ventilate when outside conditions make sense. Use small absorbers only in small spaces, and move to a proper dehumidifier when the room shows persistent evidence that it needs one.

Most importantly, do not accept recurring leaks, failed extraction or building damage as a lifestyle problem you must quietly manage. Document it and report it.

The goal is not simply to wake up to a cleaner window.

It is to understand why the water is there—and use the smallest effective solution to stop it returning.

Affiliate Disclaimer: Some links in this article may be affiliate links, which means we may earn a commission at no extra cost to you.