What is the minimum size drain pipe allowed for a clothes washer?

The minimum size drain pipe allowed for a clothes washer is 2 inches. This size is considered essential due to the significant volume of water and potential debris that can be discharged during a wash cycle. A 2-inch pipe ensures adequate drainage capacity to handle the water flow, which can be substantial due to the washer’s operation cycles. It helps prevent clogs and ensures that wastewater is efficiently transported away from the machine and into the plumbing system.

Smaller diameters, such as 1 inch, do not provide enough capacity to handle the high water discharge rates commonly found with modern clothes washers, leading to a higher risk of backups and slow drainage. Pipes larger than 2 inches can certainly be used, and they can provide even better drainage, but 2 inches is the minimum size specified in plumbing codes to maintain proper flow rates and minimize potential plumbing issues.