You walk into a room and it hits you, that damp, stale odour rising from the floor. If you’re trying to figure out how to get rid of musty smell in carpet, you’re not alone. It’s one of the most common complaints we hear from homeowners and tenants across the Central Coast to Newcastle region, especially after wet weather or in rooms with poor ventilation.
The good news? Most musty carpet smells can be tackled at home with items you probably already have in your kitchen or laundry. Baking soda, white vinegar, and a bit of elbow grease go a long way. But knowing when a DIY fix will work, and when the problem runs deeper, saves you time, money, and frustration.
At SMK Carpet Cleaning, we deal with odour-affected carpets regularly as part of our professional carpet cleaning services. We’ve put this guide together based on what actually works, drawing on years of hands-on experience treating carpets in homes and rental properties. Below, you’ll find practical, step-by-step methods to neutralise that musty smell yourself, plus guidance on when it’s worth calling in a professional.
Why carpets smell musty and what it means
Musty odours in carpet almost always come down to one thing: moisture that has been sitting too long. When your carpet fibres, backing, or underlay stay damp, mould and mildew spores begin to grow and release gases called microbial volatile organic compounds (MVOCs). Those compounds are exactly what you’re smelling, and they won’t go away on their own until the moisture source is removed.
The main culprits behind the smell
Moisture gets into carpet in several ways, and identifying which one applies to your situation is the first step in knowing how to get rid of musty smell in carpet. A pet accident or spilled drink that wasn’t dried properly is one of the most common causes. High indoor humidity, a slow roof leak, or condensation from a poorly ventilated room can also leave carpets holding far more moisture than they should, especially in rooms without adequate airflow.
If your carpet has been wet for more than 48 hours, there’s a strong chance mould has already started growing beneath the surface, not just on top of the fibres.
Your underlay is particularly vulnerable because it traps moisture and warmth, creating exactly the conditions mould needs to spread. You might not see any visible discolouration on the top surface, but the smell will keep returning until the underlay itself is treated or replaced. This is why surface-only cleaning often fails to fix a persistent musty odour.
What the smell is telling you about the damage
The intensity of the smell gives you a rough guide to how serious the problem is. A mild, musty odour that appeared after a humid week usually means the moisture is still in the fibres themselves and hasn’t penetrated deeply. This is the easiest scenario to fix at home with basic household products. A strong or persistent smell that doesn’t shift after airing the room out suggests the problem has reached the backing or underlay, or that mould growth is more established and widespread.
There’s also a meaningful difference between a carpet that smells musty due to age and one that smells musty because of an active moisture issue. Old carpets absorb years of dust, skin cells, and organic matter, which gradually breaks down and produces odours even without visible mould. Deep cleaning can make a significant difference in those cases. However, if the smell appeared suddenly after a wet event or water damage, the source is still active, and you need to address that before any cleaning treatment will actually hold.
What to do before you start
Before you grab the baking soda or start spraying vinegar, take a few minutes to assess what you’re actually dealing with. Rushing into treatment without preparation can push moisture deeper into the underlay or spread mould spores further across the carpet. A bit of groundwork first makes every step after this one more effective and far less wasteful.
Check the current condition of your carpet
Get on your hands and knees and press your palm firmly into the affected area. If the carpet feels cold, damp, or springy underfoot, it still holds active moisture and you need to dry it before applying any treatment. A dry but smelly carpet is a different situation and usually responds well to the baking soda method covered in Step 2.
Never apply baking soda or any cleaning product to a carpet that is still wet, as this traps moisture and makes the mould problem worse.
Gather everything you need before you begin
Having your supplies ready before you start means you won’t need to leave the area mid-treatment. Working on a musty carpet in stages, with gaps between each step, reduces the effectiveness of the treatment and extends the time your floor spends in a compromised state.
- White vinegar (standard distilled, not apple cider)
- Bicarbonate of soda (baking soda)
- A spray bottle
- Clean white cloths or old towels
- A stiff brush or carpet brush
- A vacuum cleaner with strong suction
- A fan or dehumidifier if available
Working through the steps on how to get rid of musty smell in carpet is far easier when everything is laid out in front of you. Stopping mid-process to find missing items breaks the drying and treatment cycle and reduces your results.
Step 1. Find the source and dry the carpet fast
Before any deodorising treatment can work, you need to remove the moisture that is causing the smell in the first place. Treating a carpet that is still damp or sitting over a wet underlay will only trap the problem deeper, and the musty odour will return within days. Your first task is to locate exactly where the moisture came from and cut it off.
Locate where the moisture is coming from
Walk slowly across the affected area and press down with your foot or palm in different spots. Soft, spongy, or cool patches indicate where moisture has pooled beneath the surface. Once you find the wet zone, think back to what caused it: a spilt drink, a pet accident, condensation from a poorly ventilated room, or water tracking in from outside. Knowing the source helps you decide whether a one-off drying job will fix it or whether you have an ongoing leak or humidity problem that will keep re-wetting the carpet.
If you find the carpet is wet in a spot you cannot explain, check the ceiling, skirting boards, and nearby walls for signs of a slow leak before you do anything else.
Dry the carpet thoroughly before anything else
Pull back any furniture from the area and open every window you can to increase airflow across the floor. Point a pedestal fan directly at the wet section and run it on high for at least four to six hours. If you have a dehumidifier, place it in the same room and let it run overnight. For heavier saturation, press dry towels firmly into the carpet and stand on them to draw moisture up from the backing. Repeat this with fresh towels until no more dampness transfers across. Once the carpet feels dry to the touch, you are ready to move on to learning how to get rid of musty smell in carpet using vinegar and baking soda in the next step.
Step 2. Deodorise with vinegar and baking soda
With your carpet dry, you can now tackle the smell directly. White vinegar and bicarbonate of soda work well together because they attack the odour from two different angles: vinegar kills the bacteria and mould spores producing the smell, while baking soda absorbs the remaining odour compounds left in the fibres. Used in the right order, these two household products are among the most effective tools for how to get rid of musty smell in carpet without expensive equipment.
Apply white vinegar first to kill the odour at its source
Fill a spray bottle with undiluted white vinegar and mist it evenly across the affected area. You want the fibres lightly damp, not soaked. Work in small sections so you can control how much moisture you are adding back into the carpet. Allow the vinegar to sit for ten to fifteen minutes before blotting it dry with a clean white cloth. The vinegar smell itself will fade as it dries, usually within an hour or two, and it takes the musty odour with it.
Do not scrub the carpet while it is wet with vinegar, as this can spread mould spores and damage the fibres.
Follow with baking soda to absorb what remains
Once the vinegar has dried completely, sprinkle a generous, even layer of bicarbonate of soda across the treated area. Press it lightly into the fibres with your hand or a soft brush so it makes contact with as much surface area as possible. Leave the baking soda to work for at least eight hours, overnight if you can manage it, then vacuum it up thoroughly using slow, overlapping passes. Two passes in different directions will pull out significantly more powder than a single run across the surface.
Step 3. Deep clean without leaving dampness behind
If the vinegar and baking soda treatment has lifted the worst of the odour, a targeted deep clean will remove the remaining residue and restore your carpet to a genuinely fresh condition. The critical rule at this stage is to avoid re-introducing moisture that doesn’t dry quickly. Over-wetting is the most common mistake people make when deep cleaning at home, and it is exactly what causes the musty smell to return within a few days.
Choose the right method for your carpet type
The cleaning method you use matters a great deal here. Foam-based carpet cleaners work well on most residential carpets because they lift dirt and odour compounds without soaking the backing. Apply the foam according to the product directions, work it into the fibres with a stiff brush using short, firm strokes, then let it dry completely before vacuuming. For tiles or hard floors adjacent to the carpet, a damp mop with a small amount of white vinegar in the water removes any mould spores that may have spread to surrounding surfaces during the cleaning process.
Never use a steam cleaner on a carpet that has an active mould problem, as the heat and additional moisture can drive spores deeper into the underlay.
Keep air moving until the carpet is fully dry
After any deep cleaning, airflow is your most important tool. Open windows, run a ceiling fan or pedestal fan pointed at the floor, and keep the room well-ventilated for at least four hours after the final step. If the room tends to hold humidity, run a dehumidifier at the same time. You will know your how to get rid of musty smell in carpet efforts have worked when the carpet smells neutral, feels dry at the backing, and no odour returns after the room is closed up overnight.
When your carpet smells fresh again
When you complete all three steps, you should notice a significant difference in how the room smells, and the carpet should feel dry and neutral underfoot. The key to keeping it that way is ventilation and fast action whenever moisture gets into your carpet again. A damp day, an accidental spill, or a pet accident handled within the first hour will almost always stay manageable using the same methods covered in this guide.
Sometimes, though, the musty smell keeps coming back no matter what you try. That usually points to mould in the underlay or a moisture source that hasn’t been fully resolved. If you’ve worked through every step on how to get rid of musty smell in carpet and the odour returns within a week, the problem runs deeper than a DIY fix can reach. Book a professional carpet clean with SMK Carpet Cleaning and get it sorted properly, with lasting results.