I haven't had any backup problems in any of my drain lines. I am adding a 1/2 bath in my basement and after cutting into the horizontal Cast Iron Drain line under my basement slab I noticed a bunch of goop so I figured while I have direct access I should have it cleaned out. I had Roto Rooter out today to snake my main sewer line to the street. I guess I should have read some of the threads here before calling RR but we all make mistakes. The guy snaked the cast iron drain line and found no roots or obstructions and then ran a camera through the line to the city sewer. The pipe was good for about 10-15 feet from were he started the camera then there was water for about 3 - 4 feet and then clean pipe. He said that my Cast Iron pipe was sagging where there is water and I need to dig it up and replace it. Does this sound right?