Water addition to moromi

In cases where the amount of water used was less than the shikomi haigo (brewer’s recipe) called for (so-called “thick mashing” , noko (濃厚two long “o”s) shikomi), resulting in a denser mash, or where the sugar content of the mash is high for some other reason (a state called noko moromi), the high sugar level can suppress the yeast’s fermentation. High levels of alcohol can also inhibit fermentation.   Adding water to the mash in such cases lowers sugar and alcohol levels, promoting fermentation. Water which is added to the mash after the final tome (third stage) of mashing is called oi-mizu or mizu yodan (水四段, meaning “water fourth stage”).