The water that was used to boil the rice was not thrown away, but was used as an after-dinner drink just like soba yu (hot water used in boiling buckwheat noodles) or was used in other dishes.
米を茹でた湯は捨てられることはなく、蕎麦湯のように食後の飲料に用いられたり、他の料理に活用された。