Water backs up into the dishwasher from the sink, or dirty water appears in the tub when the dishwasher is off.

Safety: Turn off power before working under the sink or behind the dishwasher.

• Inspect hose routing: Ensure the drain hose has a high loop under the countertop or is connected to an air gap per local code.
• Check sink drain: Clear any clogs in the sink or garbage disposer that could force water back into the dishwasher.
• Secure hose: Use clamps or brackets to keep the hose in the proper high-loop position.
• Install air gap (if required): In some regions, an air gap is required by code to prevent backflow; have one installed if missing.

Note: Backflow can introduce food debris and odors into the dishwasher; clean the tub and filters after correcting the hose routing.