Water is the largest ingredient (by volume or by weight) in the brewing process.
If you are using tap water, boil the water for five minutes before using it to brewing to remove any chlorine. This will not be sufficient to remove chloramines. Potassium Metabisulfite can be used to remove chloramine. A simple carbon filter will remove chloramines as well as other contaminants that may affect brewing or flavor.
Various minerals may be added to excessively soft water (e.g. rain water) for those recipes that require it: In particular, calcium is an essential cofactor for the enzyme alpha amylase, which is needed to turn the starch in the barley into sugars. Minerals which are often added to water include:
- Gypsum (Calcium sulfate)
- Epsom salts (Magnesium sulfate)
- Calcium Chloride
- Kosher Salt (Sodium chloride. Regular table salt is not used due to the presence of iodine.)
- Chalk (Calcium carbonate)