What is the required distance above a laundry tray for the standpipe to prevent overflow?

The required distance above a laundry tray for the standpipe is specified as 30 inches to effectively prevent overflow. This height ensures that when water drains from the laundry tray, it does not back up into the tray itself. A standpipe that is 30 inches high provides adequate space for the water to flow through the drainage system without risk of spilling over the edge of the laundry tray, thus safeguarding against potential water damage and maintaining proper functioning of the plumbing fixtures.

This requirement aligns with best practices in plumbing to ensure efficiency and prevent hazardous conditions that could arise from flooding in the laundry area.