How to Do P-Trap Septic Lines From the House to Septic

Installing Under Sinks

• 1

  Turn the water shut-off valves under the sink clockwise to turn off the flow of water while you work. Turn on both the hot and cold water-faucet handles to drain the remaining water from the supply lines.

• 2

  Place the threaded end of a drain tailpiece against the bottom of the sink drain. Turn the compression nut on the tailpiece clockwise over the threaded end of the sink drain until tight.

• 3

  Place one end of the P-trap over the bottom of the tailpiece. Turn the nut on the P-trap clockwise over the tailpiece until tight. Point the other end of the P-trap toward the septic connection.

• 4

  Place a 90-degree U-bend piece onto the top of the P-trap opening, and secure the nut on the P-trap until tight.

• 5

  Place the other side of the U-bend piece into the opening on the septic-system drain, and turn the nut clockwise until tight.

• 6

  Turn the water supply valves 90 degrees counterclockwise, and run the faucet for 10 seconds to test the connections in the P-trap. If any water leaks, tighten the nuts further at the point of the leak.

Installing from Showers and Other Large Drains

• 7

  Turn the ball valve on the main water line clockwise to shut off the flow of water to the entire plumbing system.

• 8

  Swab the inside of one end of an ABS P-trap fitting with ABS cement. Cover the entire lip of the inside of the piece evenly with cement.

• 9

  Place the lip of the P-trap onto the tailpiece on the drain stem. Hold the piece in place for about 30 seconds while the cement sets.

• 10

  Swab the other opening on the ABS P-trap with cement, and press the septic drain pipe into the lip. Hold the pipe in place for 30 seconds while the cement dries. If the septic pipe is not directly adjacent to the P-trap, insert a section of ABS pipe that will reach between the P-trap and the septic pipe into the P-trap instead.

• 11

  Swab the inside of an ABS coupler with ABS cement, and press it onto the end of the pipe that connects with the P-trap. Swab the inside of the other end of the coupler with ABS cement, and press it onto the main septic line.