Anyone knows where or how I can get a plumbing pipe blue print of my house? I asked the city hall if they have my home's plumbing pipes blue print and they said they only have the blue print of the house but not for plumbing pipe. So I am not sure where to get it, I don't want to have to dig up the house and cut up my walls to draw them.

Two story new home with basement. Basement toilet "bubbles" and makes "gurgling" noise when clothes washer discharges. Bubbles build up in toilet bowl. Only happens when detergent present. Without detergent the water in bowl moves around and than level drops slightly. Two stacks converge near toilet. Master bath stack (3inch PVC)from second floor and kitchen/laundry room stack (also 3 inch PVC)from first floor join about five feet above toilet in the wall. This in turn joins the same horizontal line coming from the toilet about two to three feet after the toilet and in the slab and than goes to the street. Contractor says all to code and unsure why there is a problem. Lines appear clear when probed with camera. Would appreciate suggestions or direction. Thank you