A sewer scope is when an inspector or plumber sends a video camera down your sewer line. This is done either through a clean out access point in the sewer line or in some cases the toilet access point.
The inspector / plumber usually records this and they are looking for roots, intrusions, blockages or cracks or ruptures in the sewer line. These can cause backups in the sewer line and leads to very costly repairs.
If you are buying a house, you want one of these done because homeowner’s insurance may not cover the repair to the line. It also may not cover damages to the home from the backup of sewage, etc.
The TLDR; get the line scoped to avoid several thousands or more in repair and damages down the road.
