J.C.
Well, city water has a bit of chlorine in it which probably has some germ-killing power. I've never heard about the city v. well-water thing for sterilizing.
I sterilized everything every night using the Avent microwave sterilizer, a wonderful invention. (Before that, I boiled nipples and pump parts - which led to at least one pan full of melted nipples. Never trust a woman who is sleep deprived and hormonal to also keep track of hot stuff on the stove.)
Congratulations on your new baby!