On Feb 1, 3:35 pm, PirateBird wrote:
Naturally the only place I can add a new bath is the back of the house where we
want to add a 15x40 addition.

The house is on a concrete slab and has a gravity feed to the city sewer system.

Hooking into the current plumbing would mean a LOT of concrete busted up and in
places I don't want/can't bust up.

You could just run a new line and tap into the city sewage line (or
into your own line for that matter). If you rent a trencher, they will
usually dig at least four feet deep. Run your new line on the side of
the addition to the front of the house and make a turn across your
yard where you can meet your current line. You might not have the
required elevation drop to meet the line at the house, but you may
have it to meet your line in the mid point from your house to the city
line or even at the city line. I replaced my main sewage line (on a
slab) from the house to the city line and it wasn't that difficult.

Pat