Effective Use of Bleach as an Antiseptic and Disinfectant

Cecil H. and Michele H. Fox point out the disinfecting properties of inexpensive and universally available diluted bleach (5% sodium hypochlorite) as an important germicide to help control the spread of influenza (or any other communicable virus, bacteria, or fungus) (Microbe, April 2006, p. 159). A few more details might help for the effective use of diluted bleach as an antiseptic and disinfectant. Bleach is sold as a stable alkaline solution with a pH value of about 11 or 12. At this alkaline pH value, virtually all of the bleach is in the form of the chlorite ion (OCl−). At an acidic pH value of about 6.0 to 6.8, 90% of the bleach is in the form of hypochlorous acid (HOCl). Hypochlorous acid is 80 to 200 times more antimicrobial than the chlorite ion. Thus a simple formula to prepare an effective antimicrobial dilution of bleach is to add 2.0 oz of concentrated bleach to one gallon of tap water, and then add 2.0 oz of 5% distilled white cooking vinegar, also inexpensive and commonly available, to lower the pH of bleach to about 6.0. This will yield about 800 ppm free available chlorine from hypochlorous acid. Use this acidified bleach in well-ventilated areas as there will be a mild odor of chlorine. The acidified bleach must be prepared fresh daily. Protect eyes and mucous membranes. Never add ammonia to bleach. Follow the safety directions as found on the bleach label.