We gave our kid formula with room temperature water for the entire duration of him being on formula. We never heated it ever, and he was fine with it.

How much would you kill for a barista style formula dispenser? :-) First world problem, I know, but I always imagined, 'click-click' and getting exactly the right amount. New fridges have water dispensers where you can set the ounces on the door, and they dispense exactly that amount. I wonder if they can set the temperature precisely too? I guess just another way our kids will not face the same set of challenges. (Not necessarily 'have it better' just applying their energy differently with a whole different set of expectations to go along with it)

This was exactly the solution we got to. The do-gooders were incensed at the system. Not having to heat it up or fart about at night (once the child is trained) is excellent. And as a bonus, our tap water is very clean, so sterilized bottle and tap water for formula. Refrigerated is even better, well done! Question. Twins, have you ever slept?

With my first two children, they took it at room temperature. Third was born in the winter and tap water was considerably colder and he wouldn't take it.

I would heat an exact amount of water for a specific time in the microwave to get a specific temperature. I started reducing the time in the microwave by one second a day and he never noticed.