Side by side
| Bleach (sodium hypochlorite) | Hydrogen peroxide (3%) | |
|---|---|---|
| Kills bacteria and viruses | Yes, broadest spectrum | Yes, most common ones |
| Norovirus | Yes | Yes, with 5–10 min contact |
| Bacterial spores (C. difficile) | Yes | Partial |
| Mould | Kills surface mould; poor penetration into porous material | Kills mould and penetrates porous surfaces slightly better |
| Contact time | 1–5 minutes | 5–10 minutes |
| Fumes | Yes, irritating | None |
| Dangerous mixtures | Ammonia, acids/vinegar, alcohol, other cleaners | Vinegar in the same container (peracetic acid) |
| Residue | Salt, needs rinsing on food surfaces | None (water and oxygen) |
| Bleaches fabric and surfaces | Strongly | Yes, more slowly |
| Corrodes metal | Yes (stainless, aluminium) | Mildly on some metals |
| Shelf life once diluted | 24 hours | Stable in dark bottle; loses potency in light |
| Environmental | Toxic to aquatic life until it breaks down | Breaks down to water and oxygen |
| Asthma concern | Yes, with regular use | No |
When bleach is the right choice
- Norovirus or other stomach-bug outbreaks in the house — bleach is the CDC's recommendation for contaminated surfaces
- Anything involving C. difficile or other spore-forming bacteria
- Mould on hard, non-porous surfaces you want gone today
- Whitening white cotton laundry
- Sanitising water in an emergency (a few drops per litre — follow official guidance)
- Disinfecting after flooding or sewage contamination
When hydrogen peroxide is the right choice
- Daily kitchen and bathroom disinfection
- Pet areas and litter boxes — no fumes, no ammonia reaction with urine
- Blood and organic stains on fabric
- Grout, cutting boards, sponges, toothbrushes
- Any household with asthma, small children, or birds
- Mould on porous surfaces like grout and unsealed wood, where peroxide's slower action penetrates a little better
- Anywhere ventilation is poor
How to use each properly
Bleach: dilute about 20 ml (4 teaspoons) of regular 5–6% bleach per litre of water, or 1/3 cup per gallon. Make it fresh — it loses potency within a day. Clean visible dirt first, apply, leave wet for at least one minute (five for norovirus), then rinse food-contact surfaces. Open a window. Never combine with any other product, including in the same bucket or on the same surface in the same session.
Hydrogen peroxide: use 3% straight from the bottle in a dark spray bottle, or the original brown one with a sprayer fitted. Clean first, spray, leave wet for 5–10 minutes, wipe. No rinsing needed except where bleaching could matter. Replace opened bottles after about six months.
Neither is a cleaner — both work on surfaces that have already been cleaned of grease and dirt.
The mixing rule
Bleach plus ammonia (in many glass cleaners and in urine) makes chloramine gas. Bleach plus vinegar or acidic cleaners makes chlorine gas. Bleach plus alcohol makes chloroform. All three send people to hospital every year. Hydrogen peroxide has one comparable hazard: mixed with vinegar in a single container it forms peracetic acid, a strong irritant. The safe practice for both is the same — use one product at a time, rinse between products, and never combine anything in a bottle or bucket.
Is it in your product?
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Common questions
Is hydrogen peroxide as effective as bleach?
Nearly, for household purposes. It kills bacteria, most viruses including norovirus, and fungi, but needs longer contact time and is less reliable against bacterial spores. For the average kitchen or bathroom the difference doesn't matter; for outbreak cleaning, bleach wins.
Can I use bleach and hydrogen peroxide together?
No. They don't form a toxic gas the way bleach and ammonia do, but they neutralise each other and you lose the effect of both. Use one, rinse, then the other if you have a reason to.
Which is better for mould?
On hard surfaces, bleach removes it faster. On porous surfaces (grout, drywall, wood), neither penetrates well, but peroxide does slightly better and doesn't leave the surface wet with salt that mould can regrow on. For serious mould inside walls, neither is the answer — remove the material.
Which is safer around pets?
Hydrogen peroxide, clearly. No fumes, no reaction with urine, nothing left behind once dry. Bleach can be used on pet areas only if fully rinsed and dried, and never on urine.
Related
Sources
- CDC, Cleaning and Disinfecting Your Home; Norovirus prevention guidance
- US EPA, List N
- CDC, Guideline for Disinfection and Sterilization in Healthcare Facilities
- Washington State Department of Health, Dangers of Mixing Bleach with Cleaners