Master inspection sequence (rough-in, testing, cover-up), DWV/water/gas pressure tests with pass/fail criteria, flushing/purging, and concealment approval requirements. No shortcuts on testing.
Key Takeaways
DWV water test: fill line, observe 15 minutes, pass if drop ≤ 1 inch; fail if drop > 1 inch.
Why This Matters on the Exam
Testing and inspection are the gatekeepers of code compliance. About 8-10% of exam questions address inspection checkpoints, testing methods, and when concealment is permitted. Understanding these topics demonstrates mastery of the entire system. You know when work is complete and ready for inspection. You understand what inspectors check. You can explain testing protocols to customers. You avoid costly rework and callbacks.
I've seen contractors lose money because they didn't understand the inspection sequence. They'd pour concrete before pressure testing, or request final inspection before rough-in approval. Inspection is the foundation of code compliance. Get this wrong, and nothing else matters.
What You Must Know
The golden rule of plumbing inspection: No concealment without approval.
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Golden rule: no concealment without written approval from rough-in inspection and pressure testing pass.
Concealment means covering with drywall, insulation, concrete slab, backfill, or building materials obscuring piping.
Water supply flushing required after pressure test passes; run 5–10 minutes per story until water runs clear.
Gas lines require sediment trap before every appliance control valve; must slope to prevent sediment pooling.
Final inspection verifies all fixtures operational, no leaks, trap seals present, vents functional, water clear.
Concealment means:
Covering with drywall, insulation, or flooring
Covering with concrete slab or backfill
Covering with other building materials that obscure the piping
Once concealed, correcting code violations becomes extremely expensive or impossible. Inspectors verify compliance BEFORE concealment to prevent catastrophic failures after occupancy.