The Australian renter's guide to mould

Mould is not a sign that you keep a dirty home. It is a moisture problem, and rentals stack the odds toward moisture in a few specific ways. Rental stock skews older, so the walls, windows, and roofs have had more years to develop small leaks and gaps. Maintenance often runs behind, because a repair has to travel from you to an agent to an owner before anything happens, and a slow drip behind a wall has weeks to feed mould while that goes on. Fit-outs are frequently the cheapest option that met code at the time, which means single-glazed windows that stream with condensation, bathrooms with a weak fan or no fan at all, and few or no wall vents.

The type of rental matters too. Ground-floor and basement flats sit closer to damp ground and rising damp. Apartments share walls and often have a bathroom with an internal duct instead of a window, so the only way moisture leaves is through a fan you do not control. Older heritage places tend to have solid, uninsulated walls that stay cold, and a cold wall is exactly where warm, moist air turns back to water. None of that is your doing, and none of it is fixed by cleaning harder. It is fixed by managing moisture and, where the building is at fault, by getting the building repaired.

Then there is the part you cannot touch. As a tenant you usually cannot install an exhaust fan, add wall vents, replace windows, or improve wall insulation, even when those are the real fixes. You are managing the symptoms of a building you are not allowed to change. Cost pressure adds to it: heating and running a dryer cost money, so damp air sits in the room longer and finds the coldest surface to settle on. To see why that cold surface is where mould always starts, read how mould grows on a wall, because every renter tactic below is aimed at breaking one link in that chain.

This is the question that decides everything, and the honest answer is that it depends on the cause, not on who noticed it. The general principle across Australian states and territories is a split. If mould grows because of a building fault, the owner is responsible for fixing it. If mould grows because of everyday living moisture that was not managed, that side sits with the tenant. The dividing line is the source of the water.

Owner or agent responsibility usually covers a roof or gutter leak, a burst or weeping pipe, a leaking shower recess or failed waterproofing, rising damp from the ground, a broken exhaust fan, and windows or doors that let water in. These are structural, and they go to the property being reasonably fit to live in, which is a standard your tenancy laws set. Tenant responsibility usually covers condensation from showers, cooking, and drying clothes indoors that was left to sit, furniture pushed hard against cold walls with no airflow, and not reporting a small problem until it became a large one. Because the detail and the exact wording vary by state, read your rights and repair obligations as a renter before you write to your agent, so you frame the issue as the right kind of problem.

One thing to hold onto: even where the cause is clearly a building fault, you are still expected to take reasonable steps to limit the damage while it is being fixed, and to report it promptly. Doing the small, sensible things does not admit that the mould is your fault. It protects you. The grey area is condensation, because a tribunal will ask whether you took reasonable steps: did you use the fan, air the rooms, and report the mould, or did you shut a wet bathroom up for months? You do not have to be perfect. You have to be reasonable, and a short record of the habits you kept is what shows that.

The goal for a renter is different from the goal for an owner. You want to clear visible mould without marking, staining, or corroding a fitting you will be charged to replace at the end of the lease. That rules out the reflex reach for undiluted bleach. Bleach can lighten coloured grout, perish silicone sealant so it lifts at the edges, dull painted surfaces, and mark natural stone, and it mostly bleaches the mould pale rather than clearing the root in a porous surface. A faded shower stain can read as damage on an exit report.

Porous surfaces are the hard case. Grout, silicone, plaster, and raw timber draw moisture in, so mould roots below the surface and a quick wipe only lifts the top. On those, give any treatment real contact time, and accept that a deeply stained, aged sealant bead may be fair wear the agent replaces, not something you can scrub back to white without wrecking it.

Spot-test first, every time. Before you put any product on grout, silicone, painted plaster, laminate, timber, or stone, try it on a small hidden patch and leave it. Look for colour change, softening, or a dulled finish before you commit to the whole area. This one habit is what keeps a cleaning job from turning into a bond deduction.

A bond-safe method for surface mould on a hard, sealed area looks like this:

1. Ventilate the room and keep pets and children out while you work.
2. Wipe the area with a damp microfibre cloth to lift loose growth, then bin the cloth or wash it hot afterwards so you are not spreading it around.
3. Apply your chosen mould treatment to the surface, and give it the contact time the label states.
4. Wipe clean, then dry the surface completely, because any product left on a wet surface is undone by the next shower.

Whatever you use, favour something mild that is kinder to the fittings you do not own than a harsh chemical: a treatment that clears surface mould without corroding grout, perishing silicone, dulling paint, or marking stone, given real contact time on porous areas. For the detail of which treatments are safe on which surface, and which fittings to leave well alone, this walkthrough of surface treatments that are gentle on rental fittings goes fitting by fitting. And be honest with yourself about scale: if mould covers more than roughly a square metre, or sits behind tiles, in a ceiling, or under carpet, that is a repair to report, not a cloth job.

You cannot re-plumb the bathroom or cut in a new vent, but almost all rental mould is a condensation problem, and condensation is a habit problem as much as a building one. The core move is simple: get the moist air out of the room quickly, and stop it landing on the coldest surface. The main guide to stopping mould before it starts covers this in full, and the renter version is really just that guide with the building changes crossed out.

The daily habits that move the needle most in a rental:

• Run the exhaust fan through the whole shower and for a good fifteen to twenty minutes after, and if there is no fan, open the window and shut the door so the moisture leaves through the window, not into the hallway.
• Squeegee or wipe the shower walls and screen after use. Removing the surface water is the single cheapest thing you can do.
• Dry washing outside or on a balcony wherever you can. A load of laundry drying on an indoor rack can release several litres of water into the room.
• Put a lid on pots and run the rangehood or open a window when cooking.
• Leave a hand-width gap between furniture and cold external walls, and crack wardrobe doors now and then so still, damp air cannot pool in the corners.
• Wipe the condensation off single-glazed windows in the morning rather than letting it run down into the frames.

Bathrooms deserve their own attention, because they combine the most moisture with the coldest tiled surfaces and the worst airflow in most rentals. A focused routine for the room that causes the most trouble is set out in this piece on keeping mould from returning to a rental bathroom, and it is built around the assumption that you cannot touch the fan or the tiling.

What should you actually buy? Keep it to things you can take with you and that leave no mark on the property. A squeegee, a few microfibre cloths, a moisture meter or a cheap hygrometer so you can see when a room climbs above about sixty percent humidity, moisture-absorber tubs for wardrobes and still corners, and a gentle mould treatment for the wipe-down. A dehumidifier is the strongest single tool, but it is an expense and it uses power, so if that is out of reach for now, the same result comes from a stack of habits instead. This rundown of how to control rental mould without buying a dehumidifier is the low-cost path, and for many renters it is enough.

Documentation is the renter's real protection, and it starts on day one, not the day mould appears. When you move in, photograph any existing damp, staining, or mould on the entry condition report and note it in writing, because anything you do not record can be read as yours later. From then on, build a simple record as things happen.

A useful mould file holds:

• Dated photographs of every affected area, with something for scale and a wide shot that shows which room it is.
• Photos of the likely source if you can see it: a stained ceiling under the bathroom above, a rusting pipe, a gap around a window, a swollen skirting board.
• A short log with dates: when you first saw it, when you reported it, what you were told, and whether it grew.
• Copies of every message to the agent, kept in writing rather than by phone, so there is a trail.
• Any receipts for cloths, absorbers, or treatments you bought to manage it in the meantime.

Keep the tone of the record factual, not accusing. You are building a clear picture of a moisture source and a timeline, which is exactly what a tribunal or an insurer would want to see if it ever goes that far.

Raise it in writing, always, even if you also call. A written request creates the date that everything else hangs off. Keep the first message plain and specific: name the room, describe what you can see, attach the photos, state what you think the source is, and ask for it to be assessed and repaired. Ask for a response within a reasonable time, and say that you are managing the surface in the meantime, so it is clear you are acting in good faith.

If the reply is slow or the problem is dismissed, the path generally runs like this. First, a formal written repair request or notice, in the form your state uses, which starts an official clock. Some faults that let water in can count as urgent repairs, which carry shorter timeframes. If that still brings nothing, you escalate to your state or territory tenancy authority or tribunal, such as NCAT, VCAT, QCAT, or the equivalent where you live, and ask for a repair order. This is where your dated file does the work, because it shows a building fault, a report, and a delay. You do not need to be combative to use this path. It exists precisely for the case where a reasonable request has not been met.

Two cautions. Do not stop paying rent or pay for a big repair yourself and deduct it, unless your state's specific process expressly allows it, because doing that off your own bat can put you in the wrong. And do not paint over mould to hide it before an inspection, because painted-over mould works its way back through the paint and reads badly on your record.

It can, which is why the habits above are worth keeping up right to the last week. At the exit inspection, the question is the same as it always was: is this mould from a building fault, or from moisture that was left to sit? Surface mould that grew because a room was not aired and was never reported can be counted against your bond as cleaning or damage. Mould from a leak or a failed shower that you reported in writing, with dates, is the owner's problem, and your file is what proves which one it is.

In the weeks before you hand back the keys, give the wet rooms a proper going-over with a bond-safe method, dry everything thoroughly, and air the place out on good days. Photograph the cleaned areas the day you leave, so the exit condition matches your record. If there is mould you could not clear because it comes from a fault you already reported, do not scrub yourself into a corner trying to hide it. Point back to your written reports instead. A tenant who reported early and managed the surface sensibly is in a strong position, and a paper trail beats a spotless wall every time.

Mould in a rental is rarely about effort and almost always about moisture and who is allowed to fix the building. Manage the water you can, report the water you cannot, and keep the receipts. This guide sits at the centre of a wider set of renter resources, and you can work through the rest of the renter mould resource index for the state-by-state detail and the room-by-room routines.

Cleaning clears what is already on the surface, but spores keep arriving on the air, which is why the rooms you scrub keep needing scrubbing. That gap is what First Light is built for. It is not a cleaner: it is a six-oil essential-oil blend, made in Australia, for defence once a surface is already clean. Run a few drops in a waterless diffuser, leave a few on a small dish in a wardrobe or under-sink cupboard, or mist a few in water over surfaces you have already cleaned. The oils carry through the air and meet spores before they settle, and they also work where they land on a surface: lab tested at a 99.2% reduction in black mould on direct contact. You clean the surface with the method above, then keep First Light going in that room day to day so mould has a harder time settling back between cleans. It is safe for daily use around children and pets, and you can find it, together with the waterless diffuser that runs it, in our range.