There won’t be any water supplied to the home yet, but shut the supply valve anyway
For rough plumbing, install caps on all supply lines except for the shower faucet. For threaded fittings, be sure to use plumber’s tape or pipe thread sealant.
Using plumber’s tape or pipe thread sealant on all threads, assemble the pressure gauge, ¾-inch nipple, reducer, and ½-inch nipple.
Thread the gauge assembly into the shower faucet elbow and tighten. Be sure you can see the gauge.
Turn the compressor on first, and then open the shower control valve to pressurize the system to the inspector’s specifications (typically two to three times the city’s pressure, between 80 and 120 PSI)
Leave the system for around an hour (or according to the inspector) to ensure that the pressure stays constant.
How To Pressure Test Waste Drain and Vent Plumbing
Generally speaking, waste drain and vent (DWV) testing is only necessary for new construction or renovations.
Because these systems usually require pressure testing before tying into the street or existing house drain, you can cap them for testing.
In years past, inspectors frequently accepted pressurizing the system with air. However, most jurisdictions are moving away from this method because plastic PVC can break or explode under pressure.
Instead, the following method is more generally accepted:
Find all clean-outs and ensure they’re tight, leaving one for testing access.
Place an expandable test cap in the pipe where the system will tie in with the sewer or existing drainage system (sometimes through a clean-out, according to the inspector’s preference)
Seal drain all pipes with caps or plugs, depending on the circumstances
Insert the test plug into the clean-out that was left loose, and fill the system with the garden hose
The inspector will usually consider the system as full when water begins to flow out of the highest vent on the roof
Allow the water to sit in the system and check for leaks
While this isn’t a “pressurized test,” the weight of the system being full does create some pressure.
In some cases, the building inspector will request that you fill the system from one of the vents rather than a test plug.
Or, in the case of extreme cold, an inspector may allow capping the system off and pressurizing the system with compressed air.
When Should a Pressure Test Be Done On Plumbing
Pressure testing plumbing might be a bit of a hassle, but it doesn’t have to occur all that often. In fact, there are really only a few cases when you should pressure test a plumbing system.
When a builder is constructing a new home, every bit of the home falls under close scrutiny of building inspectors.
Plumbing inspectors want to ensure that the plumbing system is free of leaks and major issues, and a pressure test is how they check.
Major renovations often require building permits, and those involving kitchens or bathrooms typically require plumbing work.
The building or plumbing inspector might request a pressure test to ensure that everything is working correctly.
Pressure Drop, Leaks, or Odors
Pressure tests aren’t just for inspections. They can also be helpful when looking for the cause of a pressure drop, leak, or odor.
While a puddle on the floor or crumbling wet sheetrock are dead giveaways to an issue, brick and plaster homes can hide small leaks.
If a homeowner suspects a leak due to low pressure, water, or odors, a pressure test can help them locate it.
Pressure tests require some specialized gear, and the process of testing the system might be a little messy, but it’s not a difficult task to tackle.
It’s helpful to call your local plumbing inspector ahead of time and ask about his testing preferences, as tests can vary from municipality to municipality.
With the above tips and tricks in mind, you should be able to handle any plumbing pressure test the inspectors throws at you.