I had an issue with cheap crappy face cloths producing lot of lint which ended up clogging my main sewer and when the next load drained it backed up. I got lucky and caught it on time but had I used the washroom or worse, waited till next morning and showered I would have had water all over my basement.
I had a bit of poop backup into the sump pit, and the laundry tub was not draining either. I knew at that point that the blockage was beyond the stack but probably not far off. I'm not sure how the sump pit is connected to the main sewer - in fact I never knew it WAS till then, figured it was just a storm drain.
What I did was pour some javex down the sump mostly to kill the smell/bacteria and I plunged away at the sink for a while. This was only making the water rise in the stack mind you, but over time the water movement did push out the clog, then running tons of water washed it out. I got my sewer camed the day after and they said it was all clear.
Now I'm paranoid. everytime I take a huge dump I go check downstairs to make sure it made it through lol.
Oh and if you tend to pour greasy substances down the drain, don't! the drain guy told me that is a big issue that he sees. People will use stuff like cooking oil then just dump it in the sink. Since water goes around what happens is it starts to accumulate around the pipe, making it smaller and smaller... nothing will make that wash away other then special pipe cleaning substances, or a special snake tool. Basically it's the same thing that happens to our arteries when we eat bad!