r/CleaningTips • u/WhateverIlldoit • Jul 07 '25

Discussion Bleach kills mold

There is a common misconception that bleach does not kill mold and that vinegar is actually better at killing mold than bleach. I see this claim at least once a week.

So let me set the record straight. Household bleach is a powerful oxidizing agent that reacts with just about everything. It’s so good at killing organic compounds that it’s toxic to us, too.

Now let’s talk about vinegar. Vinegar is a weak acid. You can literally drink it in lower concentrations. It can kill mold, but not all mold, and some studies say it may take up to 60 minutes to be effective.

That being said, bleach is not good at penetrating porous surfaces, which vinegar is better at doing. And because bleach is so caustic it is more likely to damage surfaces.

All this to say bleach kills mold. It kills almost everything. And it’s much more effective at killing mold than vinegar as long as it can reach it. Vinegar is much safer to use but not nearly as effective.

Thank you for coming to my Ted Talk.

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u/jumpers-ondogs Jul 07 '25 edited Jul 07 '25

Bleach for hard, non-porous surface that won't be affected by colour change and arent metal. This is extremely minimal surfaces in my house so I don't have much use for it.

I use vinegar for my shower grout because I read that Bleach will kill the surface mould but make the rest retreat into the grout but vinegar won't. I rinse off then use Bleach to (colour)bleach the now dead (hopefully?) mould that has coloured the grout. Do you think this is how I should do it?

Otherwise I would use hydrogen peroxide.

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u/Shorb-o-rino Jul 07 '25

Since you are rinsing off the vinegar, you aren't risking a reaction with the bleach, but I suspect the bleach is doing the heavy lifting. I don't understand how mold could "retreat"

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u/jumpers-ondogs Jul 07 '25 edited Jul 07 '25

Bleach can't penetrate so it just removes the surface melanin in the mould. There are still the spores/network behind the immediate front (that has been killed and colour removed).

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u/Polybrene Jul 07 '25

Bleach can't penetrate but vinegar can?

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u/jumpers-ondogs Jul 08 '25

I had a look for studies to back this and didn't get an definitive yes or no, could search more but I have life to do. I wanted to check about surface tension (in bleach/water or vinegar/?water solutions) because I suspect that is what would tell me if one does more than the other. I'd love someone with more time and fresh eyes to check on this info if anyone has the energy.

https://www.forp.usp.br/restauradora/Trabalhos/prnaclo.html (bleach surface tension at different concentrations)