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How to Attach a New Pipe to the Main Sewer Line

Steve Sloane

Most household sewer lines are made of either ABS (Acrylonitrile Butadiene Styrene) or PVC (Polyvinyl chloride) plastic. The home's main sewer line, either three or four inches in diameter, runs from the basement/buildup area underground to the city sewer, or to a private septic tank. Most individual sewer lines from your water fixtures connect to the main sewer line via a connecting coupling. This coupling is the same diameter as the main sewer line, and has a side spout that fits to the sewer pipe running to the water fixture.

Use a circular saw to cut through the main sewer line.
  1. Mark the main sewer line pipe at the point where the new sewer pipeline will attach to it. Make a second mark on the sewer line 2 inches along from the first mark. Make a straight perpendicular cut through the main sewer line at both marks using a circular saw or handsaw --- the two cuts will be parallel with each other. Take out the 2-inch pipe section. Use 80-grit sandpaper to remove all burrs from the existing sawed pipe ends.

  2. Brush PVC primer around the outside of both sawed pipe ends, to a width of 3/4 inch --- both primer and cement tins have brushes attached to their lids. Next, prime the inside ends of a PVC connecting coupling. Brush PVC cement on all four primed areas.

  3. Squeeze the connecting coupling between the main line's sawed pipe ends, pushing the pipe ends into each end of the coupling --- make sure the coupling's side-spout faces upward and in the direction of the water fixture it will eventually connect to. Hold the pipes to the coupling for 10 seconds to let the cement set.