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Ask Dr. Laundry

Ask Dr. Laundry

Shelf Life of Bleach/Water Solutions

By Dr. Laundry November 4, 2010

Q. I found your videos to be a great wealth of information and much appreciated. I was glad to learn that hot water helps disinfect. The CBS program was terrible to not check their facts first. I think I have watched and read every video and/or article, but how long can the water-to-bleach ratio be stored?

My mother worked for a hospital that said the bleach/water solution for disinfecting surfaces is perfect, however, they made them discard any unused solution at the end of the day. Is this necessary? I like to use this for my counters, and cannot see myself mixing a new batch every morning. My mother was told after 24 hours, it does not disinfect. Is this true?

A: I’m glad you liked the videos—the previous Dr. Laundry, Harold Baker, made them, and did such a terrific job. Now that he has retired and moved to Arizona, I am enjoying answering the laundry questions that come in to the blog. Your question is particularly interesting. How long ago did you see the CBS program? Regarding how long you can store a bleach solution, it depends on what bleach solution you are mixing, and how you intend to use it. Because we mention different bleach and water solutions in the videos, I’ll go over both of them. Generally, longer-term storage is not recommended because diluted liquid bleach solutions are susceptible to degradation from a variety of sources. Increased temperatures, contamination and even light (that’s why it’s sold in opaque bottles) can cause the liquid bleach active to break down into salt and water. Not knowing your home’s environment, I would suggest the following:

Bleachability Test Solution (1½ teaspoons Clorox® Regular-Bleach added to ¼ cup water) Stored at room temperature (70°F) away from light, this solution should be good for at least 2–3 weeks since it isn’t used for disinfecting. Because this solution is used only for testing laundry items to see if they can be safely bleached and you may not do that on a regular basis, I would definitely write the date and the contents on the container. That way, you won’t accidentally test with too weak of a solution because it is older than you thought.

Disinfecting Bleach Solution (½ cup Clorox® Regular-Bleach added to 1 gallon water) The disinfecting solution has very specific instructions for mixing and use because Clorox® Regular-Bleach is registered with the EPA as a disinfectant, with efficacy assured by following label instructions. Your mom’s hospital was correct to ensure its effectiveness (critical in a hospital environment) by mixing a fresh solution daily, but I can also understand that you don’t want to make it up every day if you don’t have to. To simplify things for you, you could make a smaller amount (2 tablespoons diluted in 4 cups water) that you use up over several days for general countertop cleaning. However, when you are cleaning up after things that are highly likely to spread bacteria (like raw meat), you would want to use a freshly mixed solution. You could also try Clorox® Clean-Up® Cleaner with Bleach. It’s really convenient for home use, with a specially designed sprayer mechanism that’s compatible with bleach and won’t corrode.

Remember to always follow the label directions, and I hope this helps. Please let me know if you have any further questions.