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Heat drastically reduces the effectiveness of bleach. IE: You don’t wash whites with bleach in hot water.

Clorox would be to differ with you suggestion. From their website:

“For maximum cleaning, stain and soil removal, one should wash with hot water with detergent and Clorox® Regular-Bleach. For household cleaning and disinfecting, Clorox® Regular-Bleach is the most cost-effective disinfectant and can be used in hot, warm or cold water.Aug 12, 2010

Water Temperature and Bleach | Clorox®
Clorox › laundry-basics › bleach-101

I have a friend who told me that in college he was told that hot water makes bleach less effective. Is this true? I always wash my whites in the hottest water. Thank you for your input.
A.

Thanks for the great question. Here is what I would tell your friend: washing white and safely bleachable colorfast items with Clorox® Regular-Bleach in the hottest water possible will give you the best cleaning and whitening performance because its effectiveness increases with temperature. Perhaps you would like to avoid an “I’m right, and you’re wrong” gloating response to his opinion (not really good for a friendship) by applying what he was told to the proper storage of bleach. In that case, he is correct: Clorox® Regular-Bleach should ideally be stored at room temperature (70°F) because the active ingredient in liquid bleach, sodium hypochlorite, is very sensitive to high heat storage conditions. Basically, you want to store it at normal room temperature to prolong its active life, and when you add it to a load of laundry, use hot water because you want it as active as possible for the best performance. As a bleach user, he definitely sounds like a friend worth having!

Recently my family was cleaning my grandma’s house. I was using hot water with bleach to wipe things down, thinking I was disinfecting the surfaces. My sister-in-law informed me that when you use hot water with bleach, you deactivate the bleach. I have never heard this before, is this true? She said to only use cold water with bleach when cleaning.
A.

She’s probably referring to the CBS Early Show segment on Germ Warfare: The Laundry Room. While I didn’t see it live, I have reviewed the presentation and the only thing that I took issue with was their “expert” and his comment about bleach losing its efficacy in hot water.

The facts are:

Clorox® Regular-Bleach disinfects effectively in hot, warm or cold water whether for laundry or household cleaning/disinfecting.

For maximum cleaning, stain and soil removal, one should wash with hot water with detergent and Clorox® Regular-Bleach.

For household cleaning and disinfecting, Clorox® Regular-Bleach is the most cost-effective disinfectant and can be used in hot, warm or cold water.

Overall, the consumer has several choices to obtain sanitizing and disinfecting with Clorox® Regular-Bleach.

Hope this clears up any confusion on the subject. Let me know if you have any further questions.

One of the first things I learned in chemistry is that heat increases the rate of chemical reactions. That would presumably include bleach’s effect on bacterial proteins.

Weirdly enough, according to a German college website, the body’s immune system works in a similar manner:

http://news.rub.de/english/press-releases/2018-03-06-immune-system-bleach-main-ingredient-toxic-cocktail-destroying-bacteria
When bacteria enter the blood stream, neutrophil granulocytes, the most common white blood cells, are the first line of defence. They literally devour the invaders – a process that is referred to as phagocytosis. They engulf each bacterium and shower it with a toxic cocktail made up of so-called reactive oxygen species. Those include hydrogen peroxide, an ingredient of many antiseptic agents, and chlorine bleach. These substances destroy the molecules of the bacterium through oxidation – a chemical reaction, in which the oxidation states of atoms are changed.