Many authorities such as the internationally renowned WHO, AAP, UNICEF and authoritative parenting books give feeding advice: do not feed water to babies under 6 months of age. In fact we need to respect the voice of science, but also according to the situation and the time.
Since breast milk is about 90% water, as long as you are exclusively breastfeeding and the following four points are met before the baby is 6 months old, it means that the baby's body does not need additional water.
1. Baby's weight growth is within the normal range