Hydrogen peroxide to remove chlorine from brewing water

Congratulations, you made me pull out my ancient chemistry knowledge and periodic table data. (I'm a chemical engineer by degree, but that was more than 20 years ago. Hope I still know what the heck I'm doing!)

Based on molecular weights and the fact that sodium hypochlorite reacts with hydrogen peroxide thusly:

NaOCl + H2O2 --> NaCl + H2O + O2

So if the aqueous concentrations of chlorinated water and hydrogen peroxide were the same (say, at 3%), then it appears that you would need 34/74.5 = 45.6% as much hydrogen peroxide as the chlorinated water. But then I doubt water from your tap would contain 3% sodium hypochlorite. Looking that up... it appears that a common municipal water system actually ensures the amount of sodium hypochlorite flowing from your tap is not at 3% but rather up to about 3 parts per MILLION. So that is 1/10,000 as much as I originally calculated. So that's 45.6/10,000 = 0.00456% as much hydrogen peroxide you will need to neutralize the hypochlorite compared to the volume of chlorinated water. Or volumetrically that's 0.0456 ml per liter of water, or would be about 0.006 ounces per gallon, or ~4 drops per gallon.

I understand the reaction is very fast, virtually instantaneous. It should definitely work.

Interesting idea. Thanks for the question! I might give this a try sometime.