Massachusetts Plumbers Journeyman Practice Exam

The proper method for discharging indirect waste piping into the building drainage system is through an air gap or air break. This approach is crucial for preventing any potential contamination of the potable water supply that could occur from backflow or siphonage. An air gap creates a physical separation between the waste discharge and the drainage system, ensuring that any sewage or waste materials cannot travel back into water supply lines due to negative pressure or backflow situations.

Using an air break or air gap also aligns with plumbing codes and safety regulations, which aim to protect public health. This method is effectively used in various applications, such as sinks, dishwashers, and other fixtures where waste might be disposed of indirectly.

Other options, while they have their own applications in plumbing, do not provide the same level of protection against contamination and are not compliant with the established plumbing standards for indirect waste discharge.