What must be removed when connecting a dishwasher drain to a garbage disposal?

• A. Knock out plug
• B. Gasket
• C. Air gap
• D. Trap adapter

Answer: (B)

The essential step is removing the knockout plug inside the garbage disposal’s dishwasher inlet to create an opening for the dishwasher drain. This plug sits in the side inlet and is meant to be knocked out; until it’s removed, the dishwasher drain has no path into the disposal. You typically drive it out with a screwdriver and a hammer, tapping along the scored line, after ensuring the power is off. Once the plug is removed, you can connect the dishwasher drain hose to that inlet with a hose clamp, following local codes for backflow prevention (air gap or high loop, as required).

The other parts aren’t what allows the connection. The gasket helps seal the connection, but isn’t the opening that must be removed. An air gap is a separate device used to prevent backflow into the dishwasher, not something you take out of the disposal. A trap adapter is the fitting that connects to the P-trap, not the passage for the dishwasher drain.