Journeyman Plumber ExamDrainage, Waste, and Venting (DWV) SystemsMedium
A plumber is conducting a water test on a newly installed DWV system in a two-story residential building. The highest fixture served by the system is a bathtub on the second floor. To properly test the system, to what level must the water be filled?
- ATo the top of the highest fixture served by the stack.
- BTo a point 5 feet above the highest fixture served by the stack.
- CTo the highest point of the stack vent.
- DTo the rim of the lowest fixture.
Show answer & explanationAnswer & explanation
Correct answer: A. To the top of the highest fixture served by the stack.
For a water test on a DWV system, the water must be filled to the highest point of the system or to the highest fixture served by the stack being tested. This ensures that all joints and sections of the drainage system are subjected to adequate pressure.
Why the other options are wrong
- B. 5 feet above the highest fixture is an unnecessarily high pressure and could overstress the system, potentially causing failures.
- C. Filling to the top of the stack vent is usually excessive and unnecessary, as the vent portion itself is not under drainage pressure.
- D. Filling only to the lowest fixture would not test the upper portions of the DWV system.
DWV Water Test Level
The required filling height for a water test on a DWV system to ensure all parts are adequately pressurized and check for leaks.
- Fill to highest fixture or highest part of system.
- Maintained for a specific duration (e.g., 15 minutes).
- Checks for visible leaks at joints and connections.
Memory trick: Test high, no lie, for a dry pipe by and by.