Like adults, babies need to drink plenty of fluids to avoid becoming dehydrated. You know your baby is hydrated if there are six to eight pale wet diapers a day.
For the first 6 months when your baby is only on breast milk or formula, you shouldn’t be giving them any water. But during hot weather, you may find your baby may want to feed more than usual but for shorter periods.
Once they are on solids, you can give your baby small amounts of cooled boiled water throughout the day. If your baby wakes at night, they’ll probably want milk but if they’ve had their usual milk feeds, try some cooled boiled water as well.