my main sewer line was replaced approximately 7 to 10 years ago. I had it scoped and was informed that there was some water standing in the sewer line from the clean out valve for approximately 15 feet. at the 15 feet point the sewer line flowed normally. I have never had any problems with the line whatso ever. My question is it critical to have the line repaired and if so what must be done.
Critical... not likely, but if water is laying in the line, there is the chance that it has settled at a joint or even broken. The problem is probably a bad job of supporting the pipe when the trench was dug and back-filled. The water laying in the line will start impeding the flow, especially solids, and could cause a clog or back-up.
If you have never made a mistake, you haven't done much.