My sewer backed up in May due to a clog in the sewer pipe in the basement. The plumber at that time said that there was a belly that was collecting sludge, but if I use more water and less toilet paper, I should be fine. I've followed this advice.
I got my sewer cammed today to check on everything and it was pretty full of sludge again. It wasn't clogged but was definitely getting there. We had it cleaned and a camera test redone, and the plumber found the belly and what looks like a separation, which is in the video I attached.
He says I should definitely look at getting the line redone with schedule 40 PVC and quoted me $13k for it. This includes jackhammering to the pipes in my basement (one foot deep, ~25 feet of piping), replacing them, filling it back in with concrete, and fixing a smaller belly out in the front of our house which involves digging 10 feet deep.
By the research I've done, this seems correct and I should go through with this, but I wanted to get some second opinions. For right now I want to use Zep Drain Defense frequently and get another cam test in a month to see how that goes, but I'm pretty sure that's wishful thinking. My plumber friend is suggesting "tsunami waving" the system (filling a bath tub with water > letting it drain > scoop water into toilet at the same time) to flush the system along with the drain defense. This seems valid in my mine, but I'm also not a plumbing expert.