pretty bad when i'm the fist to post in here ! but had to get up early & call some septic companys ..... got one coming later thank god .......
My moms toilet was backing up one time so I went to look at it. The solids had backed up from the septic tank into the house. Looking at her drain pipes was a nightmare. She had cast iron, schedule 40, schedule 30, Copper, galvanized steel, and ABS pipes just on the drain lines. She had CPVC and polybuytle in addition on the supply lines.
I replaced it all with copper and schedule 40 except the cast iron from the septic tank.
I had the tank pumped and had to gut the house plumbing to correct the problems. I also had to rip out the bathroom floor and the laundry room floor because the plumbers cut half of the 2x8 floor joists depth out to run drain lines.