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Ask Dr. Laundry

Ask Dr. Laundry

Bleach & Hot Water Usage

By Dr. Laundry January 22, 2010

Q. During a recent training session, an instructor told the group that using regular bleach in hot water deactivates the disinfecting properties of the bleach. Is this true? The topic at hand was the use of bleach in a machine and disinfecting the “faces” of manikins used in CPR training, if that affects your response. Additionally, will using regular bleach in cold water still disinfect surfaces? And will using the newer cold-water bleach disinfect fabric as well as clean?

A. Let’s take the questions one-at-a-time:


  • Definitely a great idea to clean up the dummies’ faces. There seems to be some confusion about hot water decreasing/deactivating the disinfecting power of liquid bleach like Clorox® Regular-Bleach. In the situation you are describing (washing the faces in a washer with liquid bleach), the amount of liquid bleach degradation will be minimal for the 10-12 minute wash cycle. I know this from laundry disinfection studies using washing machines to substantiate our EPA claims. Cloth actually would be harder to disinfect than your faces. So using 3/4 cup of Clorox® Regular-Bleach in a regular cycle in hot or warm water should provide the desired outcome. A further comment: most washers’ hot water settings depend on the hot water tank setting, which is usually no more than 110-115F and certainly won’t significantly degrade the liquid bleach.

  • One of the great things about sodium hypochlorite, the active in Clorox® Regular-Bleach, and our other liquid bleach products, is its ability to provide disinfection under a wide range of conditions. Yes, Clorox® Regular-Bleach disinfects in cool and cold water. In fact, when natural disasters occur, one of the first products recommended to help clean-up contaminated water and surfaces is Clorox® Regular-Bleach because it’s readily available and cheap (Clorox also donates truckloads to the Red Cross in these cases). In these situations, hot water is usually not available, but rescue workers know it can do the job in cool/cold water just as well.

  • Legally, I must tell you that only Clorox® Regular-Bleach can claim disinfecting properties. In the US any product that wants to make these claims must be registered with the EPA, pass a series of tests for each type of application, and abide by some fairly restrictive rules. Companies must also separately register with each state and receive approval to make these claims ( they also can charge you a tax to enrich their coffers). For these reasons, we have chosen to only register Clorox® Regular-Bleach. This is also why most private label liquid bleaches do NOT make disinfectant claims, since they have chosen not to do the large quantity of work and expense required to obtain the EPA registration. To know if a liquid bleach is EPA registered, check the back label (ours is EPA Reg No 5813-50). As stated, Clorox® Regular-Bleach will disinfect surfaces and laundry in cold water. So, I can’t tell you that CloroxPlus® Coldwater Bleach will disinfect clothes. But I can tell you it has at least the same level of sodium hypochlorite active as Clorox® Regular-Bleach.