How many fixture units can a 3/4" pipe hold?

In plumbing design, fixture units are a measure of the probable demand on a plumbing system based on the type and number of fixtures. For a 3/4" pipe, the generally accepted value according to plumbing codes, including the Massachusetts Plumbing Code, is that it can handle a maximum of 1 fixture unit. This is due to the limited capacity of a smaller diameter pipe, which restricts the flow of water and therefore the number of fixtures it can effectively serve.

Larger pipes can accommodate more fixture units, but the 3/4" pipe's designation signifies its limitations in hydraulic performance, making it suitable for single fixture use under normal conditions. This understanding is crucial for ensuring that plumbing systems are designed to deliver adequate flow and pressure to fixtures without risking interruptions or performance issues.