What is the minimum fixture drain size required for a residential clothes washer?

The minimum fixture drain size required for a residential clothes washer is typically 2 inches. This specification is based on plumbing codes that ensure the proper drainage and venting of wastewater. A 2-inch drain allows for adequate flow of the effluent generated by a clothes washer, which can discharge a significant volume of water during the washing and rinsing cycles. Additionally, a larger drain size mitigates potential clogging issues that could arise from lint and other debris commonly found in laundry wastewater.

Using a smaller drain size, such as 1 inch or even 1 1/2 inches, might not provide sufficient capacity to handle the volume of water discharged, leading to drainage problems and potential backups. Therefore, the requirement for a 2-inch drain is put in place to ensure efficient and reliable plumbing performance for residential laundry applications.