If a child is fed with milk for a month after birth, he/she does not need to drink any more water if he/she has enough milk.
Within one month after birth, if breast milk is not enough, or there are no conditions for breastfeeding, you can feed the child with milk (formula milk). Nowadays, formula milk is very close to breast milk in terms of nutrient composition, electrolyte content and osmotic pressure, so there is usually no thirst after drinking formula milk, so there are no special circumstances, so you don’t need to feed plain water.
However, if the child sweats more, or because of diarrhea, overflow and other reasons, water loss, you can drink some water moderately between meals, usually 5-10ml, but do not need to feed water daily.
Drinking more water may result in insufficient intake of the child’s formula milk itself, which may affect growth and development, so please consult your pediatrician if necessary.