I use bottled and a bottle warmer to warm it up, it seems to upset his stomach a little when it's just room temp.

I used tap, just boiled it and put it in containers.

i used tap cause thats all i could afford my daughter is fine but if you have to use tap try to get a purifier i did after a couple weeks. it saves money

i use the gerber baby water gallons at room temp.

@jackiemommyof2 and room temp or warm?

Yes it's safest.