Which of the following is used for air testing of concealed drainage piping?

• A. 5 PSI
• B. 10 PSI
• C. 15 PSI
• D. 20 PSI

Answer: (A)

Air testing concealed drainage piping uses a controlled, low pressure to reveal leaks without risking damage to joints or trap seals. Five pounds per square inch is used because it provides enough pressure to uncover leaks at joints and fittings, yet stays well within the safety limits of typical residential DWV components. This level is high enough to push air through the system to show any weaknesses, but not so high that it could blow out seals, siphon traps, or stress plastic and metal pipes. Higher pressures like ten, fifteen, or twenty psi are unnecessary for a leak test and increase the risk of damage and false indications, so five psi is the standard choice for this test.