What is the deal with chlorine?
I have been bringing city water to a boil and just letting it cool back down. Chlorine has such a low boiling point that once water hits rolling boil like 200 degree within an hour the chlorine has to have evaporated. I don’t even wait and let it set overnight. I don’t taste anything bad in the beer I’ve made so far except when I make my own mistakes.
So how does chlorine impact my beer?
Chlorine is injected as a gas into the water and diminishes as it comes in contact with various microbes or organic and metallic compounds. The use of Chloramine is replacing Chlorine because it can be added at a central point and stays stable through the whole water system. Chloramine does not gas or boil out.
Chlorine can attach to the melanoidins in malt and survive the boil. The yeast can then process the chlorine into chlorophenol as a way to sequester it, rendering it harmless to the yeast. Chlorophenol is perceptible in parts per billion, far lower than the perception of chlorine.
The amount of chlorophenol is dependent on the strain of yeast. Those yeasts that already produce phenol (like German Weizen and Belgian strains) are more likely to create chlorophenol. The strains that are typically clean won’t really create any from the amount in tap water, unless they are severely stressed, like with high fermentation temperatures. Using Chlorine as a sanitizer can create concentrations that even clean yeasts will turn to chlorophenol. Chlorophenol tastes medicinal, like burnt brown sugar (or burnt molasses) and harshly bitter.
Chlorine can be removed easily with Campden tablets. It only takes one tablet to treat 20 gallons of water. Campden is Potassium Metabisulfate, which is what wine makers use to sulfite their must. Brewers use it in far lower levels, so it doesn’t inhibit yeast activity. What happens is the chlorine is broken down into chloride, CO2 and water.