Water backs up into the dishwasher from the sink or floor drain

Safety first: Turn off power to the dishwasher and avoid using the sink until the drain issue is resolved.

• 1. Clear building drain: Use a plunger or call a plumber to clear the sink or floor drain blockage.
• 2. Inspect check valve: Remove and inspect the dishwasher's drain check valve for debris preventing closure. Clean or replace as needed.
• 3. Correct hose height: Ensure the drain hose connection is above the trap and water level to prevent backflow.
• 4. Add air gap/high loop: Install an air gap or high loop if not present.