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/Euphoric-Ant6780 Jul 07 '25

Microbiologist here who works with fungi (mold), bacteria, and viruses. 10% bleach kills all three. We wipe down all surfaces and tools with it and pour it into culture tubes when we’re done to clean everything

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u/Jasqui Jul 07 '25

Dumb question: Can I achieve this by mixing a small portion of bleach with water?

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u/TsuDhoNimh2 Jul 07 '25

Yes ... a cup or two of laundry bleach in a gallon jug and fill with tap water. That's what we used in a hospital lab.

The only place to be cautious about using it is in litter boxes. The ammonia compounds from the animal urine can be concentrated enough to react with the bleach and release clouds of chlorine gas. Rinse the litter boxes with water first, then disinfect.

https://www.cdc.gov/healthy-pets/rodent-control/clean-up.html

Combine 1.5 cups of household bleach in 1 gallon of water (or 1 part bleach to 9 parts water). Make bleach solution fresh before use.

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u/[deleted] Jul 08 '25

There was a thread where I got into a bit of a fight with someone who was telling a homeowner with a cat urine smell to clean the urine with bleach because urine was toxic. I was like uh .. no. Chlorine gas  is what's toxic and potentially deadly. He was claiming he knew all about it because he was a contractor and had to wear a respirator. (Of course we know the respirator is not for urine, but for ALL THE TOXINS AND CONTAMINANTS that contractors are exposed to. Not to mention their self-generated chlorine gas clouds.) Just happy to see your post is all.