When DD was born I had a pretty good idea what I wanted to do about most areas of her care. For example, along with breastfeeding, which I did for six months, I knew that I was going to give her one bottle of formula a day. My reasons? As an older mother, I didn't totally trust my milk to be sufficient and I wanted to see at least one bottle of milk go down. As a single mother, I wanted her to be used to the bottle so that other people could feed her occasionally and it not be a big trauma - in case I was not available for any reason. Very soon other reasons joined the list such as, when I was with friends this was important adult company time for me and I didn't want to spend half the time in another room (or at least away from the dinner table) whilst feeding.
However, I had no idea whether sterilizing bottles was required or not. As with most issues, I went looking for the answer I wanted. The sterilizing units were very expensive and would take up yet more counterspace in my already cramped kitchen.
On one side were the mothers who told me that sterilizing was left over from the past when the water supply was not treated as it is today and could not be trusted to be clean enough. On the other side, mothers of children with allergies or sensitive constitutions told me I absolutely must sterilize. Others informed me that dishwashers are sufficiently hot to sterilize as they clean - I don't have one.
In the end a comment from a paediatrician swung the balance. She told me that there was no question I must sterilize. When I asked her why, she replied that parents bring her their babies with diarrhea and they don't make the connection between the runny-tummy and the shmootsy bits left on the bottles when you wash them by hand and don't sterilize. That did it for me - I don't leave shmootsy bits when I wash-up by hand! So I didn't sterilize (although I did pour boiling water over the clean bottles in a mixing bowl for a while) and DD was fine.