It's not about adding water. The water in mash is actually the liquid produced during fermentation. The key is to control the temperature. When adding koji, glutinous rice must be placed at about 35 degrees. If it is too hot, the koji will be burned to death and cannot be fermented. Temperature should also be controlled during fermentation. You can wrap the glutinous rice jar with a quilt, put a warm water bag in the quilt, change the hot water every six hours, and you can eat it in three to five days ~

PS: It's easier to succeed in winter. Put the quilt next to the heater, so that you can use the temperature of the heater and don't have to change the water often.