Inspection - static water pressure test

[Luke Reeves]

I have the inspector coming tomorrow to test the water supply (100 psi for 2 hours) and drainage pipes (static water pressure for 15 minutes).

I plugged all the drains in all the right spots, filled the whole system with water from the roof vent.

I waited a while to let the air escape from the vent, then filled it to the top.
Came back 15 minutes later, level had dropped a little under 1/2 inch.

I looked at ALL THE JOINTS (everything is exposed), nothing leaks.

From your experience, will a 1/2 inch drop cause the inspection to fail?
If the inspector can visually inspect each joint?

Any help would be greatly appreciated!

 

[Jadnashua]

You could get a volume change because of temperature changes. But, if the water you used was cold, it would expand as it warmed up. Conversely, the cold water could cause the pipe to shrink a bit. PLastic pipe, both PVC and ABS both expand/contract a fair amount with temperature changes. Once things stabilize, it may end up holding.

Don't know the answer...

 

[Sponsor]

 

[Luke Reeves]

Turns out the lowest plug of the whole stack (where the 4" transitioned to cast iron) was passing a tiny bit of water, enough to cause that drop in level
Cheap plug from the hardware store...

Anyways, inspection passed!