Sunday, May 31, 2009

Truly sanitizing with bleachwater: 1ozBMV method

It is common to see people clean/disinfect with bleachwater. Cutting boards, countertops, baby stuff, bathrooms, etc. There are two problems with this:
  1. it is easy to use way too much bleach, wasting money, causing skin/eye/nose irritation, putting more chlorine in wastewater; and,
  2. the pH of bleach in water is too high to disinfect to its full potential. In other words, disinfecting with plain bleach is leaving money on the table. When the pH is not adjusted there is more bleaching going on than sanitizing. Think about that next time you use bleachwater on that grout or the board where you cut that chicken up.
The first trick is to find a good no-rinse dilution rate; this means you don't have to rinse the surface off after you wipe/spray with the bleachwater and it won't make your eyes and skin burn. This rate is 1 fluid ounce of unscented cheap bleach for 5gal of water. Fancy bleach has additives that inhibit the process and they cost more. To paraphrase Gordon Gekko, "cheap is good". So pull out that orange Home Depot bucket and pour 1oz of bleach in it. Add in 5gal of water.

Here's the 2nd trick, dropping the pH of the solution down from 8+ where it is now down into the 6.5-7.5 range where it works as a viciously-effective sanitizer but does not generate chlorine gas. The way to to this is to add 1 fluid oz of normal white vinegar to your mixed bleachwater. Of course you know not to mix those undiluted chemicals, right?

That's why it's called 1ozBWV; the amounts are in the name (1oz) and the order of addition is specified: Bleach first, then water, then vinegar.

This method was most famously described by Charlie Talley, a chemical engineer formerly responsible for production of Clorox bleach. He currently produces a nonbleach sanitizer for the homebrewing market. For more information, listen here.

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