Natural Ways of Combatting Mould in the Home

Last Updated: October 2026

Seven non-toxic methods that actually work, using ingredients you likely already own.

In large parts of Australia, mould is simply part of life. Northern Rivers summers, Melbourne winters, Queensland wet seasons, Sydney apartments with poor ventilation — all of them produce the kind of conditions mould loves. Warm, damp, poorly aired spaces where spores find a surface to colonise.

The default commercial response is a bottle of chlorine bleach. It works, but the trade-off is real: toxic fumes, respiratory irritation, surface damage over time, and a cleaner that most people don’t want anywhere near their food preparation surfaces or small children.

The good news is that bleach is almost never the only option. Household ingredients you likely already own will handle most domestic mould situations without any of the downsides. Here are seven methods that actually work.

Before you start: what causes mould in the first place

Mould needs three things to grow: moisture, warmth, and a surface to colonise. Remove any one of those three and mould can’t establish.

The honest truth is that no cleaning method, natural or otherwise, will keep mould away permanently if the underlying moisture problem isn’t addressed. A bathroom with no exhaust fan, a bedroom with condensation on the windows, a cupboard pushed hard against an outside wall, a laundry that never fully dries out — these are moisture problems first and mould problems second.

Before reaching for the spray bottle, check:

• Are exhaust fans running during and after showers?
• Are windows opened for cross-ventilation on dry days?
• Is damp air being extracted from bathrooms, laundries and kitchens?
• Is furniture allowing airflow against outside walls?
• Are wet clothes being dried outside or in well-ventilated rooms?

Fix the moisture, then clean the mould.

1. Hydrogen peroxide

Our strongest recommendation for most household mould situations. Food grade hydrogen peroxide at 3% is a powerful antimicrobial that leaves no toxic residue and breaks down into water and oxygen when it finishes working.

Method: Spray undiluted 3% hydrogen peroxide directly onto the mouldy surface. Leave for 10 to 15 minutes. Scrub with an old toothbrush for grouted or textured surfaces, or wipe with a clean cloth for smooth surfaces. Rinse with warm water.

For stubborn grout mould, make a paste of hydrogen peroxide and bicarb soda, apply, leave for 30 minutes, scrub and rinse.

Food grade is important here because it contains no stabilisers, preservatives or additives — just pure hydrogen peroxide and water. For a full walkthrough of concentrations, dilution and safe handling, see our complete guide to food grade hydrogen peroxide.

2. White vinegar

White vinegar is a natural mild acid and antimicrobial. It won’t tackle the heaviest mould jobs on its own, but for routine mould prevention and lighter mould, it works well and leaves surfaces fresh.

Method: Fill a dark glass or opaque spray bottle with undiluted white vinegar. Spray directly onto the mouldy surface. Leave for at least one hour. Wipe clean with warm water.

The vinegar smell dissipates within a few hours once the surface is dry. Vinegar is particularly good for routine shower and bathroom maintenance between deeper cleans.

3. Hydrogen peroxide and vinegar used sequentially

A combination that works noticeably better than either ingredient alone — but only when used one after the other, not mixed in the same bottle.

Important: Never combine hydrogen peroxide and vinegar in a single solution. The two react to form peracetic acid, which is a respiratory irritant and should not be in a household spray bottle. Keep them in separate bottles and use them sequentially on the same surface.

Method: Spray the surface with hydrogen peroxide first. Leave for 10 minutes. Wipe clean. Then spray with white vinegar. Leave for 10 minutes. Wipe clean. The two in sequence tackle a wider range of mould types than either alone.

4. Bicarb soda

Humble, cheap, and surprisingly effective. Bicarb soda is a mild alkaline that disrupts mould growth and deodorises as it works. It’s particularly good for porous surfaces where you want something gentler than peroxide.

Method: Mix one teaspoon of bicarb soda into a spray bottle of water, shake well. Spray directly onto the mouldy surface. Scrub with a brush. Rinse with clean water. Spray a second time with the bicarb solution and leave to air dry — this creates a thin alkaline film that discourages mould regrowth.

For heavier mould, use bicarb soda made into a paste with water or hydrogen peroxide.

5. Tea tree oil

The most expensive option on this list, but genuinely effective — particularly for sensitive surfaces where you don’t want anything stronger. Tea tree oil is a natural antifungal with real documented effectiveness against common household mould species.

Method: Add one teaspoon of tea tree oil to one cup of water in a spray bottle. Shake well before each use (the oil separates from the water). Spray directly onto the mouldy surface. Do not rinse — the oil continues working as it dries.

The tea tree smell is strong initially and fades within a day. Keep the spray bottle out of reach of children and pets, and don’t use tea tree oil in homes with cats, as it can be toxic to them.

6. Clove oil

Less well known than tea tree but used by professional mould remediators for a reason — clove oil kills mould at the spore level and is particularly effective at preventing regrowth.

Method: Add a quarter teaspoon of clove oil to one litre of water in a spray bottle. Shake well. Spray lightly onto the mouldy surface. Leave for 20 minutes. Wipe clean with warm water.

A little clove oil goes a long way. Overdoing it can stain lighter surfaces, so test first on an inconspicuous area, particularly on grout, caulking or painted surfaces.

7. Isopropyl alcohol

For hard, non-porous surfaces like glass, metal fittings, or sealed tiles, isopropyl alcohol at 70% strength is fast, effective and evaporates completely without residue.

Method: Spray or wipe isopropyl alcohol directly onto the mouldy surface. Leave for a few minutes. Wipe clean. Repeat if necessary.

Not suitable for porous surfaces, painted walls, or any material that could be damaged by alcohol. Test first.

Which method for which situation?

The rules to remember

• Never mix hydrogen peroxide and vinegar in the same bottle. Use sequentially on the same surface instead.
• Never mix bleach with vinegar or hydrogen peroxide. This creates toxic chlorine gas.
• Store sprays in dark bottles. Hydrogen peroxide especially degrades in light.
• Label everything. Clear bottles of unlabelled liquid in the laundry cupboard are a safety problem.
• Ventilate while you work. All of these methods are safer than bleach, but you’re still working with active ingredients.
• Test first on painted, coloured, or delicate surfaces.
• Fix the moisture source. No cleaning method keeps mould away if the room is still damp.

When natural methods aren’t enough

Household methods are perfectly adequate for the common bathroom, laundry and kitchen mould that most Australian households deal with. They’re not a substitute for professional remediation when:

• Mould covers an area larger than one square metre
• Mould is growing behind walls, under floors, or inside cavities
• The property has had significant water damage, flooding, or long-term leaks
• Anyone in the household is experiencing persistent respiratory symptoms

In those cases, call a qualified mould remediation specialist. The surface clean is a different job to the structural one.

Preventing mould long-term

The single most effective thing you can do about mould is make your home less hospitable to it:

• Run exhaust fans during and for 15 minutes after every shower
• Open windows for cross-ventilation on dry days
• Keep furniture 5 to 10cm away from outside walls to allow airflow
• Dry wet clothes outside or in well-ventilated rooms, not in sealed bedrooms
• Wipe down shower screens, bathroom tiles and window condensation daily
• Address leaks and plumbing issues promptly, however small
• Consider a dehumidifier for persistently damp rooms in winter

A weekly vinegar wipe-down of high-risk surfaces (shower, bathroom tiles, window sills, laundry) prevents most mould before it establishes.

Products at Santos that help

• Gaiaganic Food Grade Hydrogen Peroxide 3% 500ml — ready to use, no dilution required
• Gaiaganic Food Grade Hydrogen Peroxide 35% 500ml — concentrate, dilutes to approximately 6L of usable 3%
• Pure white vinegar, bicarb soda and essential oils (available in-store and online)

For more on the natural cleaning approach generally, see our complete guide to natural cleaning for Australian homes.

Related reading

• 12 practical uses for hydrogen peroxide around the home
• Hydrogen peroxide 3% vs 35%: which to buy
• The complete guide to food grade hydrogen peroxide
• The complete guide to natural cleaning for Australian homes

Frequently Asked Questions

What’s the best natural mould killer?
For most household mould, food grade hydrogen peroxide at 3% is the most effective single ingredient. It kills a broad range of mould species, leaves no toxic residue, and breaks down into water and oxygen. For routine maintenance and lighter mould, white vinegar is a good lower-strength option.

Can I mix hydrogen peroxide and vinegar?
Not in the same bottle. Combined, they form peracetic acid, which is a respiratory irritant. Use them sequentially on the same surface instead: spray one, wipe, then spray the other.

Does vinegar actually kill mould?
Yes, vinegar kills many common household mould species. It’s less effective than hydrogen peroxide on heavy or stubborn mould but works well for routine cleaning and prevention.

Is bleach better than natural methods?
Chlorine bleach kills surface mould quickly but doesn’t penetrate porous surfaces well, releases toxic fumes, damages many surfaces over time, and can actually leave mould to regrow in grout and caulking. Hydrogen peroxide penetrates better and is safer to use.

How do I prevent mould from coming back?
Address the moisture source. Mould needs moisture to grow, so ventilation, exhaust fans, drying wet surfaces, and keeping air moving are more important long-term than any cleaning product.

Is tea tree oil safe to use at home?
Yes, for most households. Tea tree oil is a strong natural antifungal and works well on mould. Keep it out of reach of children and don’t use it in homes with cats, as tea tree oil can be toxic to felines.

When should I call a professional mould remediator?
If mould covers more than one square metre, is growing inside walls or under floors, follows water damage or flooding, or if anyone in the household has persistent respiratory symptoms. Surface cleaning is a different job to structural remediation.