It's very disturbing to see water coming out of the shower drain when you flush the toilet. Yesterday, that happened. All of the toilets, shower and bathtub drains were backing up. There was water spouting up from the sewer access plug in the front yard. That meant the line between the sewer access and the street was clogger.
We went to Lowes and purchased a sewer snake, which used to clear the drain. The good news is that the drain was cleared. Some sewage overflowed into my front yard when I opened the sewer plug. That was a messy job. The bad news is that I could see a tree root down in the line. This is most likely what caused the blockage. We'll probably have to call a plumber to take care of the tree root in the sewer, but at least we can flush the toilets now.