I recently purchased my 80 year old home and am beginning to remodel. During the process, I will be replacing most of the existing iron and old copper pipe with new copper supply pipe.

I've read that it's a good idea to supply the bathrooms that have both a toilet and a shower with 3/4" pipe, and use 1/2" takeoffs to supply each fixture, to prevent water usage from affecting the shower.

I've also read that code allows 3 fixtures to be served by one 1/2" pipe. Does this mean for a given room?

I am looking for some advice on how to effectively (and intelligently) redo the supply lines in my old home. I currently have a kitchen and two bathrooms, but will be installing a 1/2 bath on the second floor in the Spring.

Any advice?