How to Test DWV Plumbing

Drain, waste and vent plumbing, or a DWV system, should be tested before inspection by a municipal code officer. Pressure tests allow you to make sure that the seals in the DWV system are airtight. This is critical because DWV systems contain potentially dangerous methane gases and waste materials that could be hazardous to your health if the pipes leak. Applying a pressure gauge and an air compressor to your system is all that's needed to test your system.

Adjustable wrench
DWV pressure gauge with air hose connection
Air compressor

Instructions

- 1
  Go to each of the cleanout plugs on your DWV plumbing and tighten the connections using an adjustable wrench. The cleanout plugs can be identified by the square knob sticking out of the cap on the sides of DWV pipes. Tighten these knobs clockwise to ensure an airtight seal.
- 2
  Remove one of the DWV plugs using the wrench, and insert the test gauge into the hole. Tighten the test gauge using the wrench.
- 3
  Turn on the air compressor and connect the supply hose to the test gauge. Allow the air to fill the pipe until the pressure gauge reads 5 pounds per square inch (psi). Shut off the compressor as soon as the gauge hits the 5 psi mark.
- 4
  Turn the relief valve on the test gauge counterclockwise until the pressure reaches 4.6 psi. This is the standard testing pressure.
- 5
  Watch the gauge for five minutes. During that time, the pressure should remain at 4.6 psi. If it dips below that, there is likely a leak in the system. If the pressure remains the same during the entire test, the system is considered sealed and safe.

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