is a very important component in the making of sake because 80% of the end product is composed of it. The quality of the water can dramatically affect the flavor of sake. Water to be used for sake-making should be good to drink, containing the proper balance of minerals such as potassium and magnesium as well as phosphoric acid. These components are optimal for the development and fermentation of the kōji (steamed rice that has been inoculated with mold) and yeast. The water in the archipelago of Japan is on the softer side; soft water has a low mineral content and allows for the creation of a light and clear sake. On the other hand, hard water has a high mineral content and one of the more undesirable components sometimes found in hard water is iron. Compared to much of the water around the world, Japan's water is better for the fermentation of sake. Wine does not require the addition of water, but beer, like sake, does.

ideally used in premium sake-making the Japanese refer to as shuzō kōtekimai or sakamai. There are many (over 100) varieties of sakamai; Yamadanishiki and Gohyakumangoku are two of the most famous. The general characteristics of sakamai differ slightly from the ordinary rice that we usually eat; the grain is larger, and it has a white center part called shinpaku where much of the starch is concentrated. Each type of sakamai has its own character and its own distinctive flavor. Wine comes mainly, almost exclusively, from grapes. Beer can use a variety of other grains, rice being one of them. Sake is 100% rice-based.

(Aspergillus oryzae) is required to break down the complex carbohydrates within the grain of rice into their component sugars. Without this step, the yeast would not be able to do their job of producing alcohol. This component (the Aspergillus orzae) does not need to be added in wine-making or in beer-making.

(Saccharomyces cerevisia) is the species of yeast used in making sake, wine, and beer. Different strains, however, are used that are ideally suited for each beverage. The job of the yeast is to break down the sugar and produce alcohol, carbon dioxide, and a whole host of other organic compounds like amino acids and other aromatics, esters, acids, etc. that are a by-product of fermentation. Even within the species Saccharomyces cerevisiae, there are numerous different strains of yeasts used in the production of sake. One of the most famous is kyōkai #7. Each strain of yeast yields variance in terms of flavor, aroma, body, etc. to the sake. Each year new strains are developed as brewers look to improve or create new sake.