Peppermint test is used to find defects in which system?

• A. Gas piping
• B. Vent piping
• C. Drainage system
• D. Water supply system

Answer: (C)

Peppermint test uses a harmless peppermint odor as a tracer to reveal leaks or defects in the drainage system. By introducing the peppermint into the drainage network, the vapor can travel through cracks, loose joints, or dry traps, and be detected at other fixtures or vents, pointing to where a leak path exists. This method relies on how air moves within the drainage-waste-vent system, so it’s specifically suited to inspecting drainage components. It isn’t used for gas piping, which requires different odorants and detectors, nor for the water supply, which is a pressurized system tested by other methods rather than scent travel.