g/plumbing • Posted by u/drain_dave • 3 days ago

Hydrostatic test pressure for PVC DWV — 5 PSI or 10 PSI?

Getting different answers from different inspectors. On a new commercial DWV system (4" PVC schedule 40, horizontal runs, no pressure application — gravity drain system), one AHJ wants 10 PSI hydrostatic test. Another jurisdiction I work in accepts 5 PSI for gravity DWV.

IPC Section 312.2 says DWV systems shall be tested at 5 PSI air or 10 feet of water column (which is about 4.3 PSI). Some jurisdictions add their own requirements.

Is there a correct baseline and what do you do when an AHJ wants more than the IPC minimum?

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u/backflow_ben • 3 days ago

Air testing at 5 PSI is actually more sensitive for finding leaks than water — a small drip shows up faster with compressed air than with static head. Some contractors prefer air tests for that reason. Just be careful: 10 PSI air in Schedule 40 PVC fittings is fine, but if there's any socket joint that's not fully cured and seated, air testing can pop it dramatically. Water fails safely.

u/pipefitter_pat • 3 days ago

IPC 312.2 is your baseline argument. 5 PSI air or 4.3 PSI water column is the national standard for gravity DWV. If the AHJ is requiring more, ask them to cite the specific local amendment to the IPC. Some jurisdictions have amendments adopted into their local code that raise the test pressure. Without a written local amendment, you can push back on the 10 PSI requirement.