How to Knock Out the Garbage Disposal Plug

On this page (8 sections)

1. When should you knock out a garbage disposal plug?
2. How do you knock out the plug safely?
3. How do you retrieve the loose plug?
4. What should you check before connecting a dishwasher hose?
5. Can you leave the plug in if there is no dishwasher?
6. Which disposal details matter when replacing a unit?
7. What if the dishwasher does not drain after installation?
8. What is the safest way to finish the installation?

To knock out a garbage disposal plug, disconnect power, tap the dishwasher inlet plug inward with a blunt tool, and retrieve the loose piece from inside the disposal. Remove it only if you're connecting a dishwasher drain hose.

The plug seals the dishwasher inlet on a new disposal. If the hose needs that inlet and the plug stays in place, dishwasher water may not drain through the disposal.

When should you knock out a garbage disposal plug?

Remove the plug only when connecting a dishwasher drain hose to the disposal. If there is no dishwasher hose, leave the plug in place.

Check the disposal's installation instructions first. The inlet and removal method can vary by model, and some units may have an open inlet already.

If you're replacing a unit, review how to replace a garbage disposal under your sink before starting. That guide covers the broader job, including removal and installation.

How do you knock out the plug safely?

Disconnect electrical power before working around the disposal. Unplug a corded unit or switch off the correct circuit for a hardwired unit, then follow the disposal manual's safety instructions.

1. Locate the dishwasher inlet on the disposal and check the manual to confirm it has a removable plug.
2. Position a blunt tool against the plug from the outside of the inlet.
3. Tap the tool gently to push the plug into the disposal chamber.
4. Look inside the chamber and retrieve the loose plug before connecting the drain hose.
5. Check that the inlet is clear, then attach the hose as directed by the disposal and dishwasher instructions.

Use controlled taps rather than striking hard. Stop if the inlet does not match the instructions or the plug does not move with light force.

What tool should you use?

Use a blunt tool that fits the inlet and won't damage its edges. A screwdriver handle or a similar non-sharp end may work if the disposal manual permits it.

Don't use a sharp blade or pry the inlet fitting apart. The aim is to push the plug into the chamber, not cut or break the surrounding connection.

How do you retrieve the loose plug?

Remove the knocked-out piece from the disposal chamber before installation or use. Look through the sink opening and use a suitable tool to lift it out, following the manual.

Don't reach into the disposal chamber with your hand. Keep the power disconnected while retrieving the piece, and make sure it is fully removed.

If you can't see the plug, pause and check the instructions for your exact model. Don't run the disposal to try to grind it up.

What should you check before connecting a dishwasher hose?

Confirm the inlet is open and the hose connection is secure before restoring power. Route the hose as the appliance instructions require, and check for leaks during the first use.

The PF WaterWorks Disposal Installation Kit includes drain fittings such as tailpieces, a drain arm, a tee, an elbow, a trap, and washers. It may suit a project where those drain parts are needed, but check that its connections match your setup.

The kit doesn't remove the inlet plug or replace the disposal's own installation directions. Check the parts you need and the pipe connections under your sink before buying.

Can you leave the plug in if there is no dishwasher?

Yes, leave the plug in place when no dishwasher hose will connect to the disposal. Removing it without a hose can leave an inlet that needs to be managed as the manual directs.

If you later add a dishwasher, check the disposal instructions before connecting its drain hose. For related electrical questions, see whether a garbage disposal needs its own circuit.

Which disposal details matter when replacing a unit?

Choose a disposal that fits your sink setup and installation plan. The knockout plug is a small step, but the new unit also needs compatible mounting and drain connections.

The InSinkErator Badger 5 with Power Cord is a 1/2 HP continuous-feed disposal with a factory-installed cord. Its compact design is described as fitting existing InSinkErator hardware, which may be useful when replacing a compatible unit.

Check that the mount, electrical connection, and available cabinet space match your installation. For a broader decision on power and fit, use the garbage disposal buying guide.

The InSinkErator Power Series 3/4 HP unit includes an EZ Removable Dishwasher Inlet Plug and an EZ Connect Hardwire Adapter. Confirm which electrical connection and dishwasher drain setup you need before choosing it.

Its power cord is sold separately. If you need to remove the old disposal first, follow how to remove a garbage disposal from a sink.

What if the dishwasher does not drain after installation?

Turn off the dishwasher and disposal, then check the hose connection and inlet plug. If the plug was not removed, disconnect power and follow the disposal instructions to clear the inlet before reconnecting the hose.

Check for a kinked or poorly secured hose, too. Avoid running repeated cycles while water is backing up, and stop if you see a leak or smell burning.

For disposal problems beyond the dishwasher connection, see why a garbage disposal may not be working. If the unit itself is jammed, use how to unjam a garbage disposal safely and keep power off while checking it.

What is the safest way to finish the installation?

Retrieve the plug, connect the hose, and follow the disposal and dishwasher manuals before restoring power. Check the connection for leaks, then run water and test the dishwasher as instructed.

If you're not sure which circuit controls a hardwired disposal, or the wiring does not match the manual, stop and contact a qualified electrician. For the plug itself, the rule is simple: remove it only for a dishwasher hose, and never leave the loose piece inside the disposal.

Frequently asked questions

Do all garbage disposals have a dishwasher knockout plug?

No. Some disposals have a removable plug at the dishwasher inlet, while others may use a different connection or have the inlet already open.

Check the unit's installation instructions before connecting a dishwasher hose.

If the inlet is open, you don't need to knock anything out.

What happens if you forget to remove the disposal knockout plug?

If a dishwasher drain hose is connected while the inlet plug is still in place, dishwasher water may not drain into the disposal. Disconnect power, remove the hose, and check the inlet according to the disposal instructions before running another cycle.

How do you know the garbage disposal plug is out?

After tapping the inlet plug inward, look inside the disposal chamber and remove the loose piece before installing or using the unit. Don't rely on sound alone.

If you can't see or retrieve it, consult the unit's instructions before continuing.

Should you remove the knockout plug if you don't have a dishwasher?

No. Leave the inlet plug in place if you aren't connecting a dishwasher drain hose.

Removing it leaves an open connection that must be handled according to the disposal instructions, so don't knock it out just in case.