A smoke test for a house is a method used by plumbers to identify leaks in the home’s plumbing system. During a smoke test, the plumber blocks off the main sewer line and then uses a machine to blow smoke into the house’s plumbing system. The smoke will then escape through any leaks in the system, allowing the plumber to identify their location. Smoke tests are especially useful for detecting sewer gas leaks, which can be hazardous to the health of the home’s occupants. By identifying and repairing these leaks, homeowners can improve the safety and functionality of their plumbing system.