Breast milk and formula are mostly water, so additional water bottles are not necessary for a young infant, nor are they recommended. Babies fall asleep when their tummies are full, regardless of what is in there. If your baby misses a feeding because he is full of water, he won't be getting the nutrition he needs.
If you are concerned your baby might dehydrate in hot weather, look for these signs:
Lack of energy
Dark yellow urine in the diapers
Skin that is not plump
If you notice any of these symptoms, call your pediatrician immediately and try to breastfeed or give a bottle of formula.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.