My question is the total amount of feet is allowed from the mainstack to the center of the toilet waste without venting

Hello Olaf:

All toilets require a vent... period. If this toilet is installed so that there are no fixtures above it, then the main stack acts a vent in and of itself.

If the toilet is off a main waste stack that picks up fixtures from above then the toilet must have an individual vent that may be between 6-8 feet (3" pipe) or 8-10 feet (4" pipe) from the toilet. Here, even if toilet is only three feet off stack, need to add a 2" vent. If toilet is to be installed 15 feet off the stack, then that 2" vent needs to be installed within 6-8 feet of the toilet itself (I assumed 3" for this).

Actual distance requirements are state or code specific but these figures represent the range between different states.

Also, some states do allow what is referred to as an AAV (air admitance valve)... but the distance requirement from AAV to toilet is the same as above.

Hope that helped some. If any more questions, just let us know.. ok? Mark