Journeyman Plumber ExamWater Supply SystemsMedium
A plumber is installing a water service line that will be buried underground. The trench has been dug, and the pipe is laid. Before backfilling, what is the minimum required pressure for the initial air or water pressure test of the water service piping, according to most plumbing codes?
- A125 PSI
- B50 PSI
- C75 PSI
- D100 PSI
Show answer & explanationAnswer & explanation
Correct answer: D. 100 PSI
Most plumbing codes (e.g., UPC, IPC) require water service piping to be tested at a minimum of 100 PSI for a duration of at least 15 minutes, or at the working pressure of the system for a longer duration, whichever is greater. This ensures the integrity of the joints and pipe material before concealment.
Why the other options are wrong
- A. 125 PSI is a higher test pressure, sometimes used for specific applications or by local amendments, but 100 PSI is the universal minimum standard.
- B. 50 PSI is generally too low for a robust pressure test of a water service line.
- C. 75 PSI is acceptable in some specific cases or for certain components, but 100 PSI is a more common minimum for the main service line.
Water Service Pressure Testing
A mandatory procedure to verify the integrity and leak-free performance of water service piping before it is concealed or put into service.
- Typically tested with air or water.
- Minimum pressure usually 100 PSI.
- Duration of test is critical (e.g., 15 minutes to 2 hours).
Memory trick: Service pipe: 100 PSI to prove it's tight.