Q. I need Dr. Laundry's help! Regarding the shelf life of liquid chlorine bleach–if the bottle is stored and unopened, does it still have a shelf life of about a year, or will it store much longer if it remains sealed?

A. Thanks for your inquiry. I have written about this previously on the blog (http://www.drlaundryblog.com/?s=bleach+shelf+life) if you want to search for a more detailed answer.

The overall answer is yes, but there are a couple of possible caveats. The active ingredient in liquid bleach, sodium hypochlorite, is very sensitive to high heat and freezing, but under normal home storage conditions, it should still perform well for nine to twelve months. So if your storage conditions were either of these, then you will have irreversibly created salt and water.

Next question is intended use. The active does decline over time and to meet our EPA disinfecting requirements, you are probably on-the-edge; so I might add a little more than the 3/4 cup Clorox® Regular-Bleach per gallon of water for any disinfecting projects. For general cleaning, you should be fine since a little liquid bleach goes a long way. Finally, I would start using it up ASAP and try not to keep it around so long in the future.