Pressur Test Bathroom DWV System

I'm putting 5lbs of pressure on the system. How long should it hold? After about 5 minutes it goes to about 4.5 lbs. Can anyone advise me?

Thanks,

Brian

It is possible that the initial loss of pressure is due to cooling of the air...if you are pressurizing with air. To get much of a pressure test.. I'd put at least 10-15 psi... wait a few minutes (maybe 5) then check pressure then check again in 15 minutes to see if it lost any pressure. I'm thinking that it should hold steady for 15 minutes... If pipes are accessible and exposed you can paint or spray on soapy water at joints and plugs.... good sudsing dishwashing liquid works great.

In Phoenix, standard the city looks for is either 10' of water head or 5lbs pressure for 15 minutes with no pressure loss...
Re-pressurize it and spray the joints with soapy water (dish soap and water works well). Any bubbles will indicate a leak... You can then fix it...

leaks

Kid's "Mr. Bubble" or similar works better because it will stick to the joint longer. Sometimes you can come back 5 minutes later and see a ball of foam at the leaking joint.