Bleach vs Hydrogen Peroxide vs Vinegar: What Actually Kills Mould?
23 October 20267 min read
Quick answer: Bleach kills and whitens surface mould on hard, non-porous surfaces like tiles and glass, but it does little inside porous materials. Hydrogen peroxide (3%) is a good middle option: it works on hard surfaces and grout without strong fumes. Vinegar is the weakest of the three and in one lab study stopped some moulds but not others, so treat it as a light-duty option. Whatever you use, never mix them, and fix the damp or the mould will come back.
In Singapore's humidity, mould is a fact of life in bathrooms, wardrobes, window frames and ceilings. Ask three people what to clean it with and you'll get three answers. Here's how the options actually compare, what they can and can't do, and how to use each safely.
How each one works
Chlorine bleach (sodium hypochlorite)
Household bleach is a strong oxidiser. It breaks down the cell structure of mould and its pigments, which is why black spots turn white quickly. That whitening makes bleach look very effective, but colour gone is not the same as mould gone. On hard, non-porous surfaces such as glazed tiles, glass and sealed counters, bleach does kill surface mould. On porous materials like wood, unsealed grout, fabric and plasterboard, it mostly works on the surface, while the water in the solution soaks in.
Hydrogen peroxide (3%)
The 3% solution sold in pharmacies is also an oxidiser. It breaks down into water and oxygen, so it leaves no harsh residue and has little smell. It works on hard surfaces and can lighten stains in grout. It's slower than bleach, so it needs time to sit. It breaks down in light, which is why it comes in a dark bottle: keep it in that bottle.
White vinegar (acetic acid)
Vinegar is a weak acid. It's excellent for limescale and soap scum, and it has some effect on mould. In a 2015 laboratory study by Rogawansamy and colleagues, published in the International Journal of Environmental Research and Public Health, vinegar inhibited the growth of one common indoor mould (Penicillium chrysogenum) but not another (Aspergillus fumigatus). That's a small study, but it supports using vinegar for light mould only.
Side-by-side comparison
| Bleach | Hydrogen peroxide (3%) | White vinegar | |
|---|---|---|---|
| Strength against mould | Strong on hard surfaces | Moderate to strong | Weak and inconsistent |
| Works on porous surfaces | Poorly; mostly surface only | Limited | Limited |
| Removes black staining | Yes, quickly | Lightens over time | Rarely |
| Smell and fumes | Strong; needs ventilation | Mild | Sharp vinegar smell |
| Bleaches fabrics and colours | Yes | Can lighten | No |
| Risks to surfaces | Corrodes metal; fades colours and grout | Can lighten coloured grout and fabrics | Etches marble, granite and limestone |
| Never mix with | Ammonia, acids (including vinegar), alcohol | Vinegar, bleach | Bleach, hydrogen peroxide |
| Best use | Tiles, glass, white sealant, toilet bowls | Grout, painted walls, shower areas | Light mould on glass and tiles, limescale |
What about plain detergent and water?
Often it's enough. The US Environmental Protection Agency's guide to mould and moisture advises scrubbing mould off hard surfaces with detergent and water and drying completely, and says using a biocide such as chlorine bleach is not recommended as a routine practice. Removing the mould physically matters as much as killing it, because dead mould can still be an allergen. The same guide notes that porous materials like ceiling tiles and carpet may have to be thrown away if they become mouldy.
Porous vs non-porous: which surfaces need which?
| Surface | Porous? | Suggested approach |
|---|---|---|
| Glazed tiles, glass, ceramic basin | No | Detergent first; bleach or peroxide for stubborn spots |
| Grout | Yes (unless sealed) | Hydrogen peroxide or a grout-safe mould remover, stiff brush, then seal |
| Silicone sealant | Surface yes, but mould grows in | Bleach-based gel on white sealant; replace if black persists |
| Painted walls and ceilings | Partly | Detergent or peroxide; repaint with mould-resistant paint if it returns |
| Wood furniture and wardrobes | Yes | Wipe with mild detergent, dry thoroughly; avoid soaking |
| Fabric, curtains, mattresses | Yes | Wash hot if the label allows; heavily mouldy items may need replacing |
| Marble and natural stone | Yes | No vinegar or bleach; mild pH-neutral cleaner, ask a specialist for staining |
For grout specifically, our guide on how to clean grout without damaging it has the step-by-step method. For walls and ceilings, see mould on walls and ceilings, and for clothes cupboards see how to deal with wardrobe mould.
How to use each one safely
Bleach
- Dilute according to the label; stronger isn't better.
- Open windows and run the exhaust fan. Small Singapore bathrooms trap fumes quickly.
- Wear gloves, and keep it away from metal fittings and coloured fabrics.
- Rinse with water after the contact time on the label.
Hydrogen peroxide
- Spray undiluted 3% solution onto the area and leave it for around 10 minutes before scrubbing.
- Test on coloured grout or painted surfaces first.
- Use a fresh bottle. Once opened and exposed to light, it gradually loses strength.
Vinegar
- Use undiluted white vinegar on light mould on glass or glazed tile, leave it for an hour, then scrub and rinse.
- Never use on marble, granite or limestone. It etches the surface.
The one rule that matters most: never mix
Bleach plus vinegar or any acid releases chlorine gas. Bleach plus ammonia releases chloramine gases. Hydrogen peroxide plus vinegar forms peracetic acid, which is corrosive. If you switch products on the same surface, rinse with water first and ventilate. Our guide to cleaning products you should never mix lists the full set of combinations.
Why mould keeps coming back
No product stops mould if the room stays damp. In Singapore, the fix is usually about air and moisture:
- Run the exhaust fan or open the window for a while after every shower.
- Squeegee shower glass and tiles after use.
- Keep wardrobes slightly open or use moisture absorbers during the wettest months.
- Use a dehumidifier in rooms that stay damp.
For a deeper look at why our climate is so hard on homes, see our guide to Singapore humidity and mould at home. If you want a product-type comparison for the bathroom, our best mould remover types for bathrooms covers gels, sprays and pastes. And for a full reset, start with our deep cleaning guide.
Frequently asked questions
Is bleach or vinegar better for mould?
On hard, non-porous surfaces bleach is stronger and also removes staining. Vinegar is weaker and, in one lab study, only stopped some types of mould. Neither works well inside porous materials, where removing or replacing the item may be the only fix.
Can I mix hydrogen peroxide and vinegar for a stronger mould spray?
No. Mixed together they form peracetic acid, which is corrosive to skin, eyes and lungs. Use them one at a time, rinse between them, and ventilate the room.
Why does black mould come back on my silicone sealant?
Mould grows into silicone, not just on its surface, so cleaners lighten it but rarely remove it. If the black marks return within weeks, the sealant usually needs to be cut out and replaced.
Is it safe to clean mould myself?
Small patches on hard surfaces are usually fine to clean yourself with gloves and good ventilation. Large areas, mould that keeps returning after leaks, or mould where someone at home has asthma or a weak immune system are better handled with professional advice.
Want mould kept in check before it spreads? Regular cleaning keeps bathrooms and kitchens from building up damp grime, and a weekly or fortnightly plan costs $23/hr instead of $26/hr. Our cleaners use the products you choose, so you control what goes on your surfaces. Book a clean or WhatsApp +65 8166 0891.