Need some assistance from the experts. I'm adding a master bath, complete with a new slab and frost free footings (20" thickened edge). the 4" main to my septic runs underneath the new addition. The location for the new tub puts it almost vertically above the 4" main and near the edge of the addition, which I think means I need to run the 2" shower drain back toward the house. What's the best way to bring the tub drain into the 4"? Below is a rough diagram
recommendations?
recommendations?