1st floor toilet bubbles when upstairs washer drains
I am a builder and have a homeowner in a new home with a concern about bubbles in the first floor toilet when the upstairs washer runs the rinse cycle. My plumber has gone under the house and moved the tie in for the washer as far as possible form the toilet. He has also inspected the lines with a camera (with water running) and confimred that there is no obstruction in the sewer line all the way to the street. In all comparable plans in the same neighborhood that are plumbed the same way we do not have the same problem. I don't want to dismiss the issue if it is a legitimate concern. However, nothing has backed up, overflowed and functioned improperly - but for the bubbles. I welcome any thoughts or suggestions on this. Thanks.