Water added to wort question

I just read in another post that their kit directions said to put cold sterile water into the primary then add the cooled down wort to this. In the kit I just made it did not say that. It said to add ice cold water to the primary then when the wort was cooled add it to the ice cold water. The water I used was filtered water off the tap in my home. I did not boil it to sterilize then cool down or anything like that.
My question is are you supposed to boil it first to sterilize the water and then cool that down before adding it to the primary?

Also, do most of you use tap water or purchase bottled spring water or something along those lines?

I have a well with good tasting water so I just use that. I've never boiled and haven't had any problems in ~15 batches. If you think you may have bacteria or chlorine in your water, you should probably boil.

Also, I don't recommend putting boiling hot water into your carboy. Especially if its glass. You don't want risk the glass breaking due to temperature changes.

I only did a handful of extract batches before moving on to AG. However, the few that I did, I just used cold tap water and did not boil. Never had an infection or anything like that.