The soil stack is the part of the toilet plumbing that runs vertically, usually behind a wall. Whenever you can’t get your toilet unplugged you’re going to have to work with this part of the plumbing to get it fixed. This is probably a job for a skilled professional, but if you have experience with plumbing, a soil stack shouldn’t be too difficult to fix.
• Find the soil stack you need to work on. It is usually behind the toilet, but you should check your home’s plumbing layout plans before you cut a hole in the wall.
• Use a saw to cut a hole in the wall where the soil stack and vent pipe is. You may need to replace these if they are getting old.
• Carefully open the junction covers; you may need oil to do this.
• Put an auger into the pipe and push it down until you meet a blockage. Turn the crank to catch the clog and try to loosen it.
• Run water through until the blockage is gone, replace the junction cover, and fix the wall.
Tips for Cleaning a Soil Stack
You have to be very careful while cleaning out a soil stack. Heavy gases can build up inside these pipes that are very flammable, make sure you also wear protective gloves.