My pediatrician told me if my lil guy gets constipated or if it's hot outside it's ok to give him 2oz of water.

I give my son one of the straw sippy cups( he loves it) with an ounce of water. My pediatrician said no more than 2 oz a day, not sure if thats how they all are or not.

My sister gave water at 4 months.... I'm thinking of doing that with Kinleigh after she eats just give her a little bit of water to basically wash away the leftovers lol....I've also slowly been introducing a sippy cup to her she isn't really to fond about it yet though

I give mine (5 months) a little water in a sippy cup with meals, so at breakfast and dinner. She typically has cereal and some kind of fruit or veggie. Not much, but I use water for the same thing. She loves it too. I am hoping it helps when I replace her night bottle with water at some point. She didn't like avocado! But we will be trying it again.