Old house (1910?) with City Sewer and a single Soil Stack to which bathroom toilet, sink and tub all connect. Bathroom is located on the second floor. When toilet is flushed the tub and sink drains gurgle, sometimes very loudly.
All house plumbing is connected to the single Soil Stack. Gurgling is heard only in the bathroom when toilet is flushed. However, when clothes washer empties (basement, in a twin tub) the water will rise and fall in the non-washer tub drain as if pulling air and will make a cyclic gurgling noise too. Possible cause, diagnoses and fixes? Thanks.