Water used in brewing should be free of chlorine since it hampers yeast growth, causes off-flavors, and, if in high concentrations, can corrode stainless steel. Chlorinated municipal water supplies will usually require treatment before use. There are several methods available to the brewer for removing chlorinated compounds, which are discussed below.
Heating the Water
Scheer reports that heating water in the holding tank at a temperature of 78°C overnight is sufficient to eliminate all chlorine, whether bound or free (22).
Activated carbon filtration is a common method used to remove chlorinated compounds, including THMs and organic pollutants such as pesticides.
Excess chlorine can also be removed by rousing 1 to 2 mg/l potassium metabisulfite into the water (21). The bisulfite at this concentration acts as a harmless bacteriostat.
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