# Hydrogen peroxide to remove chlorine from brewing water

just wanted to ask if anyone using 3% hydrogen peroxide to remove chlorine from your strike/sparge water? If yes how many ml/l or gallon? Thank you.

• Ingredients and quantity Contains 2.5 to 3.5 w / v% of hydrogen peroxide (H2O2). Contains ethanol and phenacetin as additives. Translated from Japanese Jan 15, 2020 at 22:06
• While it's possible to do this, don't most people just use Potassium Metabisulfite? Jan 17, 2020 at 19:51

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.

• Thank you for answer the question in detail, it could be better solution then camden tables and bid time saver if you need to boil brewing water, but 76 ml per liter a little scares me. I will give it a go anyway I think. Jan 15, 2020 at 5:44
• Thank you for your help, take your time:-) Will be huge time saver if it work out . Thanx. Jan 15, 2020 at 6:00
• Do you think hydrogen peroxide can impact the water profile? Can affect the taste? Thanx. Jan 15, 2020 at 9:19
• Cool answer and good use of chemistry. I'd just add that I'd be concerned about other stuff in the peroxide bottle affecting the flavor of the beer as well. I don't know if there are stabilizers or other chemicals that make up the other 97% of the bottle. H202 isn't hugely stable on its own so there must be more than just water in that 97%. Just something to think about. Jan 15, 2020 at 13:20
• Drinking water is up to 5 parts per MILLION chlorine. 0.5% would be 5 parts per THOUSAND. Thus, the calculations in this answer are correct except 1,000 times too high. Roughly, one cup of household hydrogen peroxide removes the chlorine from 1,000 gallons of water. I just did this with my pool. I tested - it did quickly remove the chlorine, using 32 ounces H202 for a 3,000 gallon pool. Note is does lower the pH slightly, as one step in the reaction is HCl, the same stuff pool owners use to reduce the pH. A bottle of household BLEACH is ~5% hypochlorite. Drinking water isn't 10% bleach. :) Sep 4, 2021 at 21:06