How to Connect a Drain Under the Sink to a Garbage Disposal

Every garbage disposal unit has an inlet and an outlet.

The inlet is inside the sink where the water and food particles enter, while the outlet is near the bottom of the disposal where it enters the drain. This connection can be made in two different ways. Either the supplied 90-degree fitting can be directly attached to a drain trap, or an extension piece of pipe can be run to connect to a drain on a double sink unit. In each case, the basic connection procedures are exactly the same.

Attach the garbage disposal unit to the sink as you would normally. The last task that is done when connecting up a garbage disposal is the drain piping.

Attach the supplied 90-degree bend to the drain port on the garbage disposal. These are supplied with all new units, or they can be found at any hardware store. Push the gasket onto the end that goes into the disposal, then line up the pipe and hand-tighten the PVC nut to make a firm waterproof connection. Alternately, instead of connecting the 90-degree pipe, attach a regular 1 1/2-inch PVC pipe in the exact same way.

Hook up the sink drain trap to either the 90-degree disposal pipe or to the extension. Push the nut onto the pipe, place the gasket over the end to be hooked up and link the pipes together. Thread the pipe nut onto the connector threads and hand-tighten it firmly.

Things You Will Need

  • 1 1/2-inch PVC drain pipe, length determinate
  • Gasket
  • PVC nut
  • Hacksaw


  • The extension can be cut to the correct length with a hacksaw if need be.

About the Author

Dale Yalanovsky has been writing professionally since 1978. He has been published in "Woman's Day," "New Home Journal" and on many do-it-yourself websites. He specializes in do-it-yourself projects, household and auto maintenance and property management. Yalanovsky also writes a bimonthly column that provides home improvement advice.