The drainage and vent rough-in on a two-story building is complete and will be proved with a water test. What does the code require for that test?
- Every part of the system is put under at least a 10-foot head of water, and the test must hold with no drop for at least 15 minutes.
- BThe system is filled to the height of the lowest fixture opening and held for 5 minutes, which is the arrangement used when testing in sections.
A column reaching only the lowest opening puts almost no pressure on the joints below it, and five minutes is the air test duration. Testing in sections still requires a 10-foot head above each section.
- CThe system is filled to any convenient level and watched for leaks while it drains, since a weeping joint shows itself.
Watching a system drain is an observation rather than a test. The code requires a head that stands without dropping, because a joint that seeps slowly will not show in the seconds water takes to pass it.
- DThe system is filled with water and then pressurized to 50 pounds per square inch for 15 minutes, matching the water distribution system test.
Fifty pounds is borrowed from the water distribution test, where pressure is the service condition. Drainage piping is proved by a head of water or by the code's air test and is never pressurized that way.
Why A is correct
The 10-foot head requirement and the 15-minute hold are what make the test meaningful: enough pressure to find a weeping joint, and enough time for a slow leak to show as a drop in the column.
What this question is testing
Whether the candidate knows the head and duration that define an acceptable water test, and how sectional testing satisfies it.
On the job
In practice you cap the stub-outs, plug the building drain and fill from the roof, then walk every joint while it stands. Fill slowly, because a fast fill on a tall stack can blow a test plug at the base. On tall buildings the code lets you test in sections so the lower piping is not overloaded, and that is worth doing rather than putting a hundred feet of head on the base fitting.
Memory technique
Ten feet up, fifteen minutes still.
Exam tip
Ten feet of head, fifteen minutes, no drop. That trio answers most water test questions.
Where to look it up
Tests and inspections are in IPC Section 312. UPC prescribes its own test heads, durations and permitted methods, and some jurisdictions restrict air testing on plastic piping, so follow the adopted code.