I recently had a new bathroom sink installed (I live in a fourplex). Right before that (one and a half weeks ago) RotoRooter was also out and snaked my main drain and the outside sewer line and cleared some tree roots. Ever since RotoRooter and the remodel, I have noticed an occasional gurgling sound deep in my pipes. It does not correspond to any water running (it doesn't happen when the toilet flushes, sink or tub are draining, etc.) It just seems to happen randomly. There are no sluggish drains (in fact my shower and sink drain better than since RotoRooter's visit). What could possible be causing the sound? It does not come from any of my fixtures. (I live on the first floor).

Gurgles indicate a vent problem. This occurs when a draining fixture attempts to vent through
Another fixtures trap. The sound you hear is air being sucked through the water in the trap.

It does not come from any of my fixtures It doesn't have to. Have you checked with your neighbors? This is a blocked vent. That should be located and snaked. Good luck, Tom