Vitamin C for chlorine/chloramine removal

A little while ago there was a thread on water chemistry, and I mentioned adding vitamin C (ascorbic acid) to remove chlorine or chloramine. For those of you who might not know, chlorine and chloramine are often added to tapwater to kill pathogens. Both chemicals can lead to off-flavors in beer. Chlorine comes out of solution relatively easily (for instance, you can boil the water or just let it sit out for a while before you perform the mash). Chloramine is more persistent. There are a variety of ways to remove them from water before brewing.

At the time I suggested using Vitamin C, I was basing the idea of using Vitamin C on this information from the San Francisco Public Utilities Commission:

Can Vitamin C be used to remove chlorine and chloramine for bathing purposes?​

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SFPUC and other utilities have used Vitamin C for dechlorination prior to environmental discharges of chlorinated and chloraminated water. Since ascorbic acid is weakly acidic, the pH of water may decrease slightly (Tikkanen et al., 2001).​

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. . .​

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SFPUC determined that 1000 mg of Vitamin C (tablets purchased in a grocery store, crushed and mixed in with the bath water) removed chloramine completely in a medium size bathtub without significantly depressing pH.​

After I posted my suggestion, I emailed Martin Brungard about the issue, and he kindly updated the "Water Knowledge" section of his website. The short version of his answer is that Vitamin C will effectively eliminate chlorine and chloramine, but it may depress the pH of the water. (But read the whole section, it is concise and helpful. In fact, read the whole page.)

I bring this up because Vitamin C is very cheap in the quantities that homebrewers would use it, and I feel comfortable adding it to my mash/sparge water in those quantities (we are talking about at most a few hundred milligrams for a 5-gallon batch, I would think, and maybe even that is overkill) [EDIT: yes, it is overkill, see below]. Also, while I have never used Campden tablets, Michael Tonsmeire (aka OldSock) has reported problems using them (for instance in this recipe). Vitamin C seems unlikely to cause comparable problems, so for some people it may be a better option. It should also be easy to find in a grocery store or drug store. I was able to find Vitamin C crystals in a local grocery/health store, and it seems easier to measure that way than it would be in tablet form (though it is hard to measure milligrams, even by the hundred, at least on my scale). I think the price probably comes out to around a penny or two per batch.

Anyway just passing this along for your consideration. Personally I intend to add a few hundred milligrams of Vitamin C to my mash/sparge water from now on, to prevent chlorine off-flavors in my beer. I will report if I notice any problems that result (though of course, it may be difficult to trace any particular problem to the Vitamin C).

[edited for formatting]

[UPDATED [twice - second time to fix math] to add: I checked NYC's water report, and the highest observed level of Free Chlorine Residual was 1.74 mg/L, with an average of 0.63 mg/L. This means that according to Martin Brungard's numbers, I can use about 1 mg/L of Vitamin C, or about 30 mg of Vitamin C in 8 gallons of water - and that is conservative, since that would take care of the highest observed level of chlorine. However, realistically I can only measure in 100's of mg's, and I don't mind adding a little extra, so I will probably end up using between 100 and 200 mg of Vitamin C per 8 gallons of water.]

 

Yeah, I mean, I guess it happened to him twice in fairly rapid succession in 2008, first with a Flanders red ale (see the notes at the bottom of the recipe), and then with a barleywine. Who knows why he had trouble where other people seemingly haven't. I don't have any insight, as I have never used Campden tablets. I will say that if I were giving advice to someone, I would probably advise using Vitamin C or a carbon block filter for chlorine/chloramine removal, and not Campden tablets.