I am currently in the process of finishing my basement and need to run supply lines (1 hot & 1 cold) to the new bathroom down there (toilet, sink, and shower). Details:

House is almost 2 years old

Waste plumbing was already roughed in

1" copper main supply

¾" copper hot & cold after water heater

I would assume that I need to branch off the ¾" copper for both hot and cold, but my question is what size pipe I should use for the branch. Can I immediately reduce down to ½" with ½" branches from that to supply the toilet, sink, and shower? Or, do I need to start out with a ¾" branch with ½" branches off of that? IÂve read that youÂre not supposed to have more than two fixtures on the same ½" branch, but I didnÂt know how much that applied when dealing with one room where, more than likely, not more than one fixture would be in use at any given time.

More details (approximate distances):

Toilet  5 from the supply branch

Sink  10 from the supply branch (5 from toilet)

Shower  15 from the supply branch (5 from sink)

I wish I would have taken more pictures of the rest of the house before the drywall went up so I could see how the other bathrooms are plumbed. Any advice you could give would be much appreciated!