This is a PSA: That Bleach and Hot Water Thing is Actually a Myth
If you’ve ever heard (or believed) that you shouldn’t mix bleach with hot water when cleaning or doing laundry, then we have news for you. Turns out that the widespread belief that hot water can render the active ingredients in bleach ineffective is nothing more than modern-day housekeeping folklore.
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We did a little digging and discovered that the myth might actually stem from the fact that bleach is actually very sensitive to high heat storage conditions—and that it should always be stored at a normal room temperature to prolong its shelf life. But if you want to mix it with hot water to boost the cleaning potential? Totally cool.
We reached out to Mary Begovic Johnson, Tide & Downy Principal Scientist to help us better understand.
Is it true that hot water renders bleach ineffective?
“This is actually a myth,” says Johnson. Both chlorine-based bleaches (the liquid jugs you’re used to) and oxygenated bleach (the type found in many laundry boosters, like Tide Whites + Brights Rescue) will retain their effectiveness in warm or hot water. “It does not deactivate the technology,” she says.
What happens if you use hot water to dilute bleach?
“When using chlorine-based bleaches and certain oxygenated bleaches, warm or hot water can help the cleaning ingredients work faster to remove stains and whiten and brighten clothes,” Johnson explains. This stems from the fact that hot water has more kinetic energy than cold water, meaning the molecules move around more quickly and, in combination with a cleaning agent, can slough away dirt or stains faster. Still, most modern cleaners, including your household bleaching agent, will work in cold water, if cost or energy savings are a factor for you.
Above all else, Johnson says you should abide by the number one rule of fabric care: Always check the label. “To prevent damage to your laundry, it’s important to first check the care label for all garments to determine if the care label advises you not to use chlorine-based bleaches due to colorfastness or other concerns,” she says.
So, there you have it folks. Not only does bleach retain its effectiveness in warm or hot water—it will help it work faster and better as a disinfectant and stain-remover, too.