What is the standard hydrostatic test for all piping in wet pipe systems?

• A. 50 psi for one hour
• B. 200 psi for two hours
• C. 150 psi for twenty minutes
• D. 100 psi for two hours

Answer: (B)

Hydrostatic testing of wet-pipe sprinkler systems is done to verify the entire piping network is sound and will not fail under pressure. The standard test fills the system with water and pressurizes it to 200 psi, held for two hours. This pressure level is chosen because it exceeds normal operating pressure enough to reveal leaks, weak joints, or damaged sections, yet is within what the piping and fittings are designed to withstand. A lower pressure or shorter test duration wouldn’t reliably reveal defects; the test needs both sufficient pressure and enough time to uncover slow leaks. After the test, the system is drained, inspected for leaks or damage, then re-filled and charged to normal operating pressure for service.