evidence: Perhaps surprisingly, that’s not the case. Babies under 6 months old shouldn’t drink water. And giving water to a little tot can cause some big troubles. "The American Academy of Pediatrics is pretty strong with their recommendations that babies in the first several months should only have human milk (breast milk) and/or formula. Not water," says pediatrician Joanna Buckingham, MD. "Babies get all the hydration they need from formula and human milk — more than that can be risky." [...] Giving your baby a bit of water on a hot day might not seem like a big deal. But avoid the temptation if your baby is younger than 6 months. Instead, if your baby is extra thirsty, offer up human milk or formula. It has all the water (and nutrition) they need — without the risk.