Hello, I'am under the UPC and I would like to know how far does a waste stack have to be and how far does a taoilet have to be from the stack. Thanks.

All plumbing fixtures are usually built in proximity of the stack with toilet right in front of it. Other fixtures are bit further away but they are usually vented back to the stack so their distance from stack doesn't really matter as much.

Are you building new or remodeling old ?

Remodeling old... so there is no exact distance where the fixtures have to be with the UPC?