Water treatment (mizu no kako)

Water treatment (mizu no kako) refers to the process of improving the quality of brewing water. In sake brewing, water is an extremely important element, and its components and their proportions have a significant influence on the taste and aroma of the sake. Water treatment is carried out when certain beneficial components are lacking, so that the enzymatic activity of koji, the growth of yeast, and the fermentation process can proceed under optimal conditions. The chemicals used for treatment are strictly regulated by the basic circular notice (kihon tsutatsu) issued under the Liquor Tax Act, and only permitted substances may be used. This makes it possible to produce high-quality sake.