How do you prepare your formula?

Ka

I have always just bought jugs of water and left it at room temp. I’ve been reading stuff about it and now I’m worried, should I be boiling my water and formula to sterilize both? I thought boiling the water was if you used tap water. I was going to start boiling tap water and putting it in jugs and leaving at room temp but I read what was in our city water and that kind of freaks me out. Also does it matter if I buy the fluoride water or not?