What is the term for the edge of a receptacle from which water overflows?

The term for the edge of a receptacle from which water overflows is the flood level rim. This terminology is significant in plumbing and building codes because it defines the maximum height to which water can rise without spilling over. The flood level rim is a critical component in designing drainage systems and ensuring that appliances, fixtures, and swimming pools are correctly installed to prevent overflow and potential damage. This term is universally acknowledged in plumbing standards, making it a key reference point for plumbing professionals.

In contrast, the other terms mentioned, such as drain rim, overflow level, and water line, do not specifically denote the point at which water actually overflows from a receptacle. Each of those terms might refer to various aspects of water management within plumbing systems but lacks the precise definition that flood level rim provides in relation to receptacles. Thus, the flood level rim is the correct and most relevant term for identifying the edge where water begins to overflow.