Water backs up into the dishwasher from the sink or disposal.

Safety first: Turn off power before working under the sink.

• Clear sink drain: Ensure the sink drain and garbage disposal are clear. Run the disposal to remove any blockages.
• Install high loop: Make sure the dishwasher drain hose is routed up under the countertop (high loop) or connected to an air gap, then down to the sink drain.
• Check hose connection: Confirm the hose is connected to the correct side of the disposal or drain tailpiece and is not submerged in standing water.

Correcting the drain hose routing usually prevents backflow into the dishwasher.