Formula questions!

Sarah • loving our little angel above us 👼🏼 • Momma to a baby boy, October 30 2018💙

I have a 4 month old baby who’s formula fed. I’ve been boiling tap water for his bottles to mix but it can sometimes be a pain. I notice some people just use bottled waters / nursery/infant waters to make their bottles. I was wondering what you mommas use and if you boil the bottled/nursery water