What is the minimum height that standpipe receptors for clothes washers must extend above the trap?

The minimum height that standpipe receptors for clothes washers must extend above the trap is 18 inches. This requirement is in place to ensure proper drainage and to prevent siphoning of wastewater back into the washer. By having the standpipe at this height, it creates a sufficient air gap that allows for effective drainage while minimizing the risk of clogs or backflow issues. This height also helps ensure that the waste water from the washer does not create pressure issues that could affect the performance of the plumbing system. Complying with this standard is crucial for maintaining sanitary conditions and proper functioning of the appliances.