There supposedly is a device, kind of like a garbage disposer, that allows you to pump the waste from a toilet through a 2-inch drain pipe. What exactly is that thing and how does it work?

Several come to mind, Exactly what did you have in mind. Single toilet, full bathroom or something between? In the mean time here's a sewerage pump system that installs outdoors so you don't have to jackhammer up the basement floor. Click on, http://www.sewagepumpsales.com/contr...or-package.htm to check it out. Cheers, Tom

Hi tom:
Congratulations to your wisdom and the efficiency in which you spread it!
This is exactly what I had in mind. We want to add a master suite with a full bathroom. A 2inch drain is available in a (to be) adjacent wall, near a (to be) exterior wall. To avoid extensive excavation, the waste would still have to travel upwards to (at least) ground level. I guess the concern is, how much backflow you can have without keeping triggering the pump.
Josef

HI Josef,

"i guess the concern is, how much backflow you can have without keeping triggering the pump."
NO, your biggest concern is this. "There supposedly is a device, kind of like a garbage disposer, that allows you to pump the waste from a toilet through a 2-inch drain pipe"
We were referring to two different drains. While the grinder pump reduces solids down to where they can be discharged through a 2" discharge outlet to your sewer, the inlet and main in your bathroom group must be 4". A toilet must have at a least a 3" pipe to flush into. (Under concrete 4"). And you haven't addressed the venting yet. The lavatory will tie into the 4" main and vent through the roof and the tub/shower will tie into the 2" lavatory drain and be wet vented by the lav. You're looking at a complete rough in and vent situation if nothing's been done yet. Not to say that this can't be done. If you have the head room you could platform the floor and lay the rough in on top of the cement or you could take the floor up and do your rough and re-cement.
You also said, " the waste would still have to travel upwards to (at least) ground level."
The grinder unit would be dug in so the 4" discharge from the house slopes into the holding tank where the grinder pump would pump it up to discharge into the existing house sewer. Sorry I couldn't be more up beat but the bathroom group needs to be roughed in the same as if it were discharging into a sewer or septic tank. Regards, Tom

Everything affirmative. Everything in the new bathroom will be roughed -in normally, but instead of draining directly into the sewer line, the waste is collected in the holding tank, erated, and pumped into the existing 2inch drain. The advantage will be that I won't have to tear up the house in search of a 4" drain, right?

If the bathroom group's roughed in normally then the 4" main will discharge into the holding tank and the grinder pump will pump it into 2" drain pipe. I'll be interested to know how you plan on connecting the 2" discharge from the underground tank outside into a 2" drain pipe in the house. Also is the rough in done or is that on the to-do list? Cheers, Tom