How to Install a Toilet Drainage Pipe

Updated February 21, 2017

Toilet drainage pipes--or sewer pipes--are made of either ABS (Acrylonitrile Butadiene Styrene) black plastic, or white PVC. The first part of the sewer line to install is the toilet flange. This is a tube with a flat lip surrounding one end, which rests on the bathroom floor. The flange is glued to a 90-degree elbow joint, which then connects to the toilet sewer line. This line then runs via a connecting coupling into the house's main sewer line.

Measure and mark the location of the toilet flange hole in the bathroom floor. Follow the toilet instructions for how far from the back wall the hole has to be, as well as any side walls close by. Rest the ABS flange over the mark, and run a pencil around the base. This will produce a circle on the floor.

Drill out the circle using a 1/2-inch wood drill bit. Push the flange down into the hole, so that the lip rests on the floor.

Glue the inside bottom end of the flange, as well as the outside male end of the 90-degree elbow joint--use ABS glue. Push the elbow joint up unto the flange, and hold for 30 seconds. This will allow the glue to dry.

Glue the inside female end of the elbow joint, and the end of a new piece of ABS sewer pipe. Push the pipe into the elbow joint, holding it in place for 30 seconds.

Glue couplings and sewer pipe as needed, so that the new toilet sewer pipe reaches over to the existing main sewer line. Cut through the main sewer pipe at the point where the new pipe will connect into it--use a hacksaw. Make sure that the cut is straight. Remove any burrs with a work knife, and wipe each side of the cut with a damp rag.

Apply glue to each side of the cut, as well as the inside of the connecting coupling. Push the coupling between the two cuts, and hold in place for 30 seconds. Make sure that the spout on the coupling's side is accessible to the new toilet sewer pipe.

Glue the inside of the coupling's spout, and the end of the new sewer pipe. Push the pipe into the spout and hold for 30 seconds.

Attach the toilet flange lip to the bathroom floor using 1 5/8-inch galvanised screws. The toilet can now be installed over the flange.


The connecting coupling is the same diameter as the existing main sewer line. The spout on its side will be the same diameter as the new toilet sewer line. If using PVC plastic sewer pipe, prime all joints first and wait for them to dry--usually a minute. Then use PVC glue to glue the joints.

Things You'll Need

  • Tape measure
  • Pencil
  • ABS flange
  • Power drill
  • 1/2-inch wood bit
  • ABS glue
  • 90-degree ABS elbow joint
  • ABS sewer pipe
  • Hacksaw
  • Work knife
  • Damp rag
  • ABS connecting coupling
  • Power drill
  • 1 5/8-inch galvanised screws
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About the Author

Steve Sloane started working as a freelance writer in 2007. He has written articles for various websites, using more than a decade of DIY experience to cover mostly construction-related topics. He also writes movie reviews for Inland SoCal. Sloane holds a Bachelor of Arts in creative writing and film theory from the University of California, Riverside.