I asked my oldest’s pediatrician when I could stop sterilizing water and bottles, I was told babies need clean, not sterile, and to just use tap water and soap and water for cleaning. It wasn’t until the internet that I learned folks in the UK sterilized. Where I live it’s not a good idea to sterilize water, homes are old so there could be lead pipes, boiling the water concentrated the lead (I always ran the water). By the time I got to #4 and #5 (twins) I did make sure I had enough bottles to use the dishwasher so their bottles were sterilized (unnecessary but easier).