Plumber how-to
How to Pressure-Test a New Water Line
Testing before walls are closed catches leaks while they’re easy to fix. Follow your local code’s test requirements.
Quick answer
Testing before walls are closed catches leaks while they’re easy to fix. Follow your local code’s test requirements. In short: cap; install; fill, then complete the remaining steps below.
Step by step
Cap or plug all open outlets.
Install a test gauge at an accessible point.
Fill the system with water (or air, where allowed) and bleed trapped air.
Pressurize to the test pressure required by local code.
Hold the pressure for the required time and watch the gauge for any drop.
Inspect every joint, then document the test for the inspector.
Safety reminders for plumbers
- Use ventilation and respirators when required for fumes and chemicals
- Follow confined-space and trench safety rules
- Wear eye protection when cutting, soldering or using drain machines
- Wash thoroughly after exposure to sewage and get recommended vaccinations
Key terms
DWV · P-trap · Vent stack · Cleanout · Backflow preventer · PEX: see the full plumber glossary.