Is it harmful to give water to babies after taking breast milk?

As a guide, for newborns younger than five weeks, consumption of water is related to increased bilirubin levels (which will cause jaundice) and excess weight loss (it will fill a baby up but has no nutritional value). It may also affect milk supply, as the baby will end up not being interested in nursing. For babies who are older, too much water will again interfere with breastfeeding by filling the babies up and causes the babies to nurse less. A baby could be given moderate amount of water when he/she starts on solids to help prevent constipation. Otherwise, there is no real need for water given the lack of nutritional value in the consumption of water.