Blocked Dishwasher Waste Pipe [exclusive] (2026)

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] ↓ [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 blocked dishwasher waste pipe

Diagnosis, Clearance, and Prevention of Blocked Dishwasher Waste Pipes: A Technical Guide Fats, oils, and grease (FOG) are liquid when