Water Reports, Chloromines and Campden Tablets, Oh my!

Your brewing water is probably one of the last things you should worry about tweaking. I’m not particularly interested in making any mineral adjustments to my water, but I think it’s worth at least having the information on hand. So, I sent a sample of my tap water off to Ward Lab this morning. When the report comes back in a couple of days I’ll have another article up about the results. The city sends out a yearly water quality report, but it doesn’t have many of the details that are important to brewing water.

I decided on probably my second or third batch that bottled spring water wasn’t worth the extra expense. When most batches cost between $25 and $40 to brew, adding another $7 to $12 for water really drives up the cost per batch. Instead, I’ve been using water right out of the tap for awhile now. Our water tastes pretty good, but does have a noticeable chlorine flavor thanks to the city water department. I’ve been ignoring it and just brewing with the chlorinated water anyway, but in an effort to refine my technique and produce the best beers I can, I’m going to change that going forward. I haven’t been able to defect any off flavors directly attributable to chlorinated water thus far, but perhaps my palette isn’t quite refined enough, or maybe I just don’t know what I should be tasting. At any rate, removing them can’t hurt, and maybe I’ll find out what I was missing.

My city (Durham) treats the water with chloromine rather than just chlorine. Unfortunately you can’t boil off chloromine, it won’t evaporate on it’s own overnight, and it’s also difficult to filter out. Luckily there is a relatively simple solution to this problem. Campden tablets are used by wine makers for inhibit the growth of unwanted wild yeast and bacteria and to end fermentation at specific gravities. This is the part where I wish I paid more attention in high school chemistry. They are made of either sodium metabisulfate or potassium metabisulfate and convert chlorine (or chloromine) into chloride and sulfate. Both chloride and sulfate are present in the water anyway, and the minor additional amount generated by the reaction is no problem at all. One tablet is enough to treat 20 gallons so I’ll only need 1/2 tablet per brew session , and my LHBS sells them in packs of 50 for less than $2.

I tested the reaction by just scraping a bit of one of the tablets into a glass of tap water. It works pretty much instantaneously and the chlorine smell and taste disappeared. I also treated the water sample I sent in as I wanted it to be representative of the water I will be brewing with in the future. I’ll be brewing with my dechlorinated tap water this weekend, the Rye IPA on deck, so I’ll report back on whether or not the results were noticeable, and of course post the recipe.

Tagged as: brewing water, campden tablets, wardlab, wardlabs, water report