Vent defects: the plumbing vent may be partly blocked. If a gurgling sound is heard at a sink or shower drain only when a nearby toilet is flushed, or at a sink or shower when a nearby tub is draining, we'd suspect that the building drain-vent system is inadequate. ...
He removed the toilet, took a hose, and sprayed water into the drain and the water went through the drain pipes no problem. After he put the toilet back on, the problem seemed to be a little better, but still noticeably slow. Putting some enzymatic stuff in there over the course of a...