I know what the dr's say, but what is the first thing they give babies after birth, glucose water, what do they give dehydrated infants, or jaundice babies? IV with saline which is water with salt. Dr really don't want you to overload the kid by watering down the formula and giving too much. This can give them fluid overload which can lead to many thing including brain damage and death. I had #3 in germany and we gave him baby tea, as well as water, otherwise he had breast milk. I gave all my summer babies water. never more than an ounce of 2 though. You are the mom and the reality is that you will not do something that doesn't feel ok. the baby may not like it or take it. I do not consider the dr. the all knowing, they just regurgitate the most recent advice on any subject, and next year it will be something else. Over the last 18 years the "medical advice" have gone through the scale of polar opposites on every subject, from feeding, sleeping, immunizations, diseases, you name it there is conflicting studies that one dr will support but another won't. I think it is funny that the reason to not give kids water is that their kidneys cannot deal with it? What do you mix formula with? Hospitals and dr give babies water often in many forms, the most common is IV, but there are water bottles to be found in every nursery and peds floor. You are a good mom, just for asking you show that. You'll do what is right for you.
BTW the sugar in it has a sedating effect on newborns, I would limit that if you want him to be alert. In the NICU We had a pet name for it, because it was sometimes the only sedative used during otherwise painful procedures.