Two common causes of dishwasher overflow are faulty water inlet valves and a malfunctioning float switch. These issues often require replacement of the damaged or faulty part. The exact cause of a particular overflow may depend on the specific model or conditions of the dishwasher.
The water inlet valve controls the flow of water into the dishwasher and is included as part of most dishwasher installations. The valve remains open only as long as needed to provide the unit with water during regular operation, and it closes to shut off the flow of water when operating normally. Water accumulation when the dishwasher is not in use is a sign that the water inlet valve may require replacement. If the dishwasher only accumulates water and overflows during regular use, reducing the amount of detergent used may eliminate the issue, according to RepairClinic.
During regular operation, a float switch in most dishwashers senses if the level of water in the washer is above expected levels. This switch can shut off the supply of water as needed. A faulty or stuck float switch may not sense the increase in water, allowing the washer to overflow. Replacing or freeing the float switch can help solve this problem.