Retired plbg1
Your pipe size goes by the amount of fix you have, each fix. is so many units and it meams that you can have so many units on a given pipe size, make a list of all your fix including your hose faucets, either take list to Plumbing dept. are maybe you can get a size from Plbg. con. It roughtly works like this.
1 bath 3/4
2to3 baths 1
3 to 4 baths 1-1/4
This is just an idea you need to go by fix units.
1″ would give you more volume, but if you have to get it inspected it might not pass, you better find out before you repipe.
