Oh yes, very important just like us 'big' people (even more important if you are nursing, I would drink almost 4qts a day of water/juice/milk when I nursed.  We are supposed to drink for maximum health atleast 64oz a day of water, human body is nearly 75% water...I'm thinking this is why I'm a bit nutty when the full moon comes,,,gravity pulls me up and my hair out!!! LOL.   Take care, Simba1

Yes you certainly can! as long as it is pre boiled which I know you have already said. Maybe also give you local chemist a call and ask about something called hydralyte. I can't say for sure if it is safe to give to a 3 month old. I know mine had it at 6 months though. Just an extra thought.