Charlie is not yet on solids & on advice from 2 professionals we do not give him water. Where we are living its currently already 34 & has been for a couple weeks. I never used to heat his bottles, just have them at room temp. Now I put them in the fridge to cool them down for him now. I agree a very small amt is ok, but that's just it...a small amt. Like Blanchie said, speak to a professional if you are not sure as it's not as simple as being casual, it can actually affect the kidneys.