Newly installed InSinkErator disposal causes dishwasher to back up into sink or leak from dishwasher hose connection

Safety first: Turn off power to the disposal and shut off the dishwasher. Have towels and a small bucket ready.

• Check for knockout plug: Disconnect the dishwasher drain hose from the disposal's dishwasher inlet. Shine a flashlight into the inlet. If you see a solid plastic wall, the knockout plug is still in place.
• Remove the knockout: Insert a screwdriver into the inlet and tap gently with a hammer to knock out the plug into the disposal chamber. Retrieve the plastic disc from inside the chamber with tongs.
• Reconnect hose: Reattach the dishwasher drain hose to the inlet and secure it with a proper stainless-steel hose clamp. Ensure the hose is not kinked.
• Verify high loop or air gap: Make sure the dishwasher drain hose has a high loop under the countertop or is connected through an air gap, per local code.
• Test: Run the dishwasher drain cycle and the disposal with water to confirm no leaks or backups.