Quoting mom2andrew&carter:" my son is 4 months old and he gets 1 bottle of water periodically a day. mostly i give him some after ... [snip!] ... oatmeal though make sure to make it with formula and not water to make sure she gets as much formula in her as possible though"
Nobody's judging, she asked
when to give water and people are answering.
And it's not really a judgement...a little bit of water probably won't hurt but too much is dangerous because their kidneys can't process it. So it's something to be discussed with the pediatrician for sure.
ETA: And formula contains more calories and fat than most foods you would give to baby, so like everyone else said...if it's a weight issue, she needs more
formula, not more solids.