[Dishwasher won't drain] ↓ [Check for standing water] ↓ [Run a drain cycle - listen for pump] ↓ [Pump runs but water remains?] → → [Proceed to waste pipe clearance.] ↓ [Pump silent/humming?] → YES → [Test/replace drain pump motor.] End of paper
Diagnosis, Clearance, and Prevention of Blocked Dishwasher Waste Pipes: A Technical Guide blocked dishwasher waste pipe
Fats, oils, and grease (FOG) are liquid when hot but solidify as they cool. Inside the waste pipe, hot, greasy water meets the cooler ambient temperature of the pipe, causing FOG to adhere to the inner walls. Over successive cycles, this layer thickens, narrowing the lumen until complete occlusion occurs. [Dishwasher won't drain] ↓ [Check for standing water]
Despite filters and macerators, fine particles—coffee grounds, eggshell fragments, rice grains, and fibrous vegetable matter—pass into the waste pipe. These particles adhere to the greasy layer, creating a dense, concrete-like composite that resists flushing. Despite filters and macerators