I would like to find out if my sewer lines in my house are leaking. I stopped up the line outside my house and ran water until my shower and bathtubs were full. I waited 5 hours and the water receded about an inch. Do you think I have a leak worth repairing? My home is 8 years old.

If it was only an inch, then it's likely an air pocket in a vent or drain line that worked it's way out over the five hours.