In my 100+ year old home there is an obvious cast-iron sewer stack extending through the house--exposed in the basement. There is also a 3" ABS pipe coming out of the slab floor in another area of the basement. This ABS pipe has no vent (even though the kitchen sink currently drains into it).

I am looking to add a bathroom on the main floor, and it would be much easier to properly vent and hook the bathroom into this pipe than extending a 3" drain line across the basement. However, I have been told that this pipe may hook into the storm system and not the regular waste system.

Is there a way to identify where this pipe goes? It is possible that it is routed into the sewer system under the slab, but I don't want to drain a toilet into it unless I know for sure.

Have the ABS line cammed to see if it ties into the cast iron line below the slab.

In a house that old it's possible that ABS pipe the kitchen sink grains into runs to a grease trap before it routes to the sewer. The only way to tell is to follow Growlers advice and run a camera through the line. Good luck, Tom

Any idea on how much this might cost?

Should I just call up a regular plumber for the job, or is there specialists?

Vanderkwaak:

Price varies by region... expect to spend between $150.00 and $250.00 for a camera inspection to be performed on your drain line.

Call a drain cleaning company or plumbing company that advertises camera inspection.

Beware of roto rooter franchise type companies... look for the smaller company that does this... price and service is usually better... ;)

Good luck!