It very much depends what the existing plumbing looks like. If the existing sewer line is below the basement slab, then it's a matter of breaking up the slab and connecting to the existing line. Since sewer lines drain by gravity, the position of the bathroom will likely be predicated by location of the existing sewer line. The other option is to install a pit and use an ejector pump. Remember that any time you turn basement space into sleeping space, you need to worry about egress. So you'll need to check with your local code enforcement folks about their requirements. As for cost, it's impossible to say without knowing a lot more about your home and where it is located but bathrooms add a lot to the cost of a basement remodel.

I live in Chicago and have a condo in a 6-unit complex. We just had our main lines and side gangway all rodded out about a month ago but we had sewer back up come up in our boiler and laundry room drains. Anyone have any idea why it would be backing up? Do we have to put a backflow preventer down by our catch basin to prevent this from happening again? Where does that water go then, stay out by the city sewers? Besides for our drains backflowing our whole building has problems with the back area flooding. Our roof tilts towards our backyard. There are 2 downspouts which flow away from the building. I guess we had the downspouts directly into the catch basin but that always overflowed our laundry and boiler rooms. Heavy rains still flood our basements; through walls, through drains. We have no idea where to put this water until it has time to drain slowly through the catch basin out to the city sewers. Any suggestions at all would be appreciated.

Around here you can figure $1000/fixture for rough-in as part of the plumbing bid. As a later add-on I would expect it to be more. Significantly less if the waste and vent lines are already done and it's only for supply lines, unless the walls are already closed up. So, as always, it depends.

Does much (if any) concrete need to be broken up if the sewage is going up and out (rather than into the floor sewage lines?). The sink hook-up is like that - the pump manually pumps it up into drainage lines to the septic, it isn't hooked into floor pipes. The sink install was just over $1000 total, including the sink, faucet, and pump. x-posted in plumbing