How to Plumb a Garbage Disposal

Garbage disposals connect to the existing under sink plumbing using slip joint connections. Slip joint connections consist of a pipe that is threaded on one end and raw on the other, a tapered slip joint washer and a nut the forces the tapered slip joint washer into the connection. The types of slip joint pipe and fittings required to plumb your garbage disposal will vary depending on whether your installation is on a single or a double bowl sink.

Things You'll Need

• Tape measure
• Permanent marker
• PVC pipe cutter
• Slip joint pipe (Dual bowl sink application only)
• Utility knife
• Pipe wrench
• Tee-main fitting (Dual bowl sink application only)
• Phillips screwdriver

Instructions

1. Rotate the garbage disposal so the discharge is facing toward the open end of the under sink plumbing. If you are installing the garbage disposal on a single sink, proceed to Step 4.

2. Measure the distance from the discharge opening of the garbage disposal to the side of the down tube coming down from the sink bowl facing the garbage disposal.

3. Mark the length on the you measured on the previous step on the slip joint pipe with the permanent marker. Cut the pipe on the mark with the PVC pipe cutter. Remove the burr left by the PVC pipe cutter by running the blade of the utility knife around the outside of the cut end of the pipe.

4. Disconnect the plumbing from the bottom of the sink to the top of the P-trap by loosening the slip joint connections with the pipe wrench. Remove the pipe(s) and set them aside.

5. Remove the discharge cover plate from garbage disposal. Slide the discharge plate over the raw end of the discharge pipe enclosed with your garbage disposal for a single sink installation or over the raw end of the slip joint pipe you trimmed to length in Step 3 for a dual sink installation.

6. Slide a slip nut and a slip washer onto the raw end of the discharge pipe or the slip joint pipe.

7. Slide the raw end of the discharge pipe into the top of the P-trap or install the tee-main fitting. Slide the raw end of the slip pipe into the inlet of the tee-main fitting.

8. Align the holes in the discharge cover plate with the mounting holes on the garbage disposal. Insert the screws with the Phillips screwdriver to secure. Reseal the discharge cover plate.

9. Attach the down tube from the sink into the top of the tee-main fitting for dual sink applications.

10. Secure the plumbing connections by tightening the slip nuts at each connection with the pipe wrench.

11. Turn on the faucet and inspect the entire installation for water leaks.

References

• InSinkErator-Installing Your Disposer