The code would prohibit you from doing that. The saniflow macerating toilet my only be installed in situations where a gravity flow drain cannot be achieved scuh as in a basement where the toilet location is lower than the house main drain. Connecting a saniflow macerating toilet is not as simple as one might think either. There are a number of code requirements that make it difficult. 1. The saniflow toilet holding tank must have a separate vent running through the roof of the structure and that vent may not be connected to any other vents in the structure. 2. Even though the discharge line from the saniflow is a 1-1/2" or 2" line, it may not be connected to a branch line in the structure. It must discharge into the house "Main Drain" and that main drain must be a 4" line.

Macerators are usually used to move sewage up such as in a basement bathroom that is below the level of the sewer line. There are very strict codes governing them and I dont think it will solve your problem. As for your last paragraph: totally unacceptable practice. I could be wrong but usually for two bathrooms one one pipe (in detroit anyway) plumbers say use 4 inch pipe. On the other hand I believe lazypup (and I trust him because I know he can provide a code reference to back it up and he has years of experience) said wet vents were not allowed for toilets, if that is the case your whole setup is non code compliant. Final note the minimum pipe size for a toilet is 3"

I did a quick search on Google using the search term septic tank and macerator and came up with a link to saniflo. If you read the page twoards the bottom you will find this, They are environmentally friendly; using less water than a normal toilet system. Ecology wise, the macerator could be seen as a primary sewage treatment system and a septic tank and/or municipal sewage treatment system as a secondary treatment I would assume from that statement they can be used with a septic tank. Plus if I remember correctly septic tanks have baffles to keep the solids from the leech field. Here is a link that might be useful: saniflo macerator

Does anyone have any experience with a macerating toilet? We are limited in our ability to add on and must utilize space within the footprint we have, with a slab foundation. This is an option to busting it up. This is a secondary bath. Thanks in advance1