The Durham System is defined as a waste system where all piping is threaded and uses recessed fittings.

The Durham System is defined as a waste system where all piping is threaded and uses recessed fittings.

• A. Copper-only system
• B. Durham System
• C. ABS system
• D. Direct waste system

Answer: (B)

The key idea being tested is recognizing how the Durham System is defined. The Durham System uses threaded piping with recessed fittings, meaning the pipes have threads that are screwed together and the fittings are set back into walls or concealed spaces so the joints don’t protrude into the interior of the waste line. This combination—threaded metal pipe plus recessed, hidden fittings—is what distinguishes the Durham System from other waste systems. In practice, threaded joints were common on older metal waste piping, offering a reliable seal and the ability to disassemble if needed. The recessed fittings help create a smooth interior surface for waste flow and keep joints out of sight within walls or chases. Modern systems typically use plastic piping with solvent-weld or push-fit joints, where fittings aren’t recessed in the same way. So, the described setup matches the Durham System because it emphasizes threaded joints and recessed fittings, unlike copper-only or ABS/plastic systems that rely on different joint methods, or a direct waste arrangement that implies a different piping and vent configuration.

The key idea being tested is recognizing how the Durham System is defined. The Durham System uses threaded piping with recessed fittings, meaning the pipes have threads that are screwed together and the fittings are set back into walls or concealed spaces so the joints don’t protrude into the interior of the waste line. This combination—threaded metal pipe plus recessed, hidden fittings—is what distinguishes the Durham System from other waste systems.

In practice, threaded joints were common on older metal waste piping, offering a reliable seal and the ability to disassemble if needed. The recessed fittings help create a smooth interior surface for waste flow and keep joints out of sight within walls or chases. Modern systems typically use plastic piping with solvent-weld or push-fit joints, where fittings aren’t recessed in the same way.

So, the described setup matches the Durham System because it emphasizes threaded joints and recessed fittings, unlike copper-only or ABS/plastic systems that rely on different joint methods, or a direct waste arrangement that implies a different piping and vent configuration.