Testing Drainage and Vent Pipes

Drainage and venting pipes are required by code to be pressure tested after installation. An improperly installed joint in a drainage pipe or vent could allow unsanitary conditions to occur inside a building as well as allow toxic gasses to enter.

Testing drainage and vent pipes(DWV) is usually done after the rough-in, by sealing off all trap arms and the building drain using plugs or inflatable balls. There are four main tests that may be performed on the DWV system; which are:

Ball test

A ball test doesn't check for leaks, but instead insures a proper grade in the drainage pipes. At the local plumbing inspectors discretion he may use a ball to check for adequate grade by inserting it into a fitting; if all is well, the ball will make it to the cleanout.

Water pressure test

When the rough-in drainage and vents are installed a water test can be performed by filling the system with at least 3 meters of water. All rough openings must be sealed and the main tightly plugged below the cleanout. The system is filled to the level of the highest point; such as the vent terminal, and the system must maintain the same water level for at least 15 minutes.

Air pressure test

Another acceptable method for testing drainage and venting is an air pressure test and is recommended if testing must be done in subzero temperatures. As with a water test, the entire system; or section your testing, must be completely sealed with air tight fittings. The system is filled with air to a pressure of 35kpa(5psi) and must maintain this pressure for 15 minutes without any drop in pressure.

Smoke test

When a system is completely installed and some sections may be obscured from view, a smoke test may be required to find leaks in the piping. To perform a smoke test, all the traps must be filled with water and the most downstream section of drainage must be plugged. A smoke generator is used to fill the system until it begins coming out the vent terminal, then it too shall be plugged or capped. Fill the system with smoke to a pressure of 25mm(1") of water column(less than 0.04 psi) for 15 minutes without adding anymore smoke. Air alone may be used on a completely installed system using the same pressure and time as a smoke test.