Which of the following is an acceptable air test pressure for sanitary sewers?

• A. Five psi for 15 minutes
• B. Ten psi for 15 minutes
• C. Three psi for 15 minutes
• D. Two psi for 15 minutes

Answer: (C)

Testing sanitary sewers with a low‑pressure air test uses a controlled air pressure to verify that joints and connections are airtight without risking damage to the piping. The standard approach is to pressurize the installed sewer lines to three psi and hold that pressure for 15 minutes. This level is just enough to reveal leaks if joints aren’t sealed properly, while staying within what the system components are designed to tolerate during testing. The 15‑minute duration gives time for any slow leaks to show up as a drop in pressure, so a steady reading indicates the piping is airtight.

Higher pressures would put unnecessary stress on seals and fittings during the test, increasing the risk of damage, while a much lower pressure could fail to uncover leaks. Therefore, three psi for 15 minutes is considered the acceptable combination for this air test.