I've reached the most mysterious step in my plumbing project, and I'm hoping you guys can help.

Here in Seattle, we're required to fill the DWV pipes with water all the way to the roof vents for the inspector to view. This is their leakage test.

So I capped every drain opening (sinks, etc) and used a knockout-style closet flange. This makes the whole thing ready for the test fill.

Question is: how exactly do I plug it at the connection to the sewer line, to keep the water from draining?

Is there some cool trick I can use?

My connection from my plastic pipe to the clay sewer pipe is exposed in the hole I dug, and connected with a rubber adapter. I was thinking I could pull the rubber adapter, slip an inflatable stint in, inflate to seal the pipe, then reconnect to the clay pipe. But then when the test is over I'll have to reverse that process, and when I deflate the stint I'll have gallons of water all over the place!

Any way around that, like some kind of remote deflator I could snake down from the cleanout (which is currently about 15 feet upstream from the rubber connector location)? Should I place a large cleanout inline right before the clay pipe? Any other ways I don't know about? Magic foam that dissolves after 2 days?

Thanks very much!

speedball1

We test our drainage the same way, by filling the stacks.
You're on the right track. We have two ways we can block off the sewer line for a static water test. One is a inflatable 4" "test ball" we blow up in the house side of the cleanout. The other is a 4" mechanical plug that expands when you turn a wingnut. You don't have to "snake " anything down. Leave the sewer tied in and install the plug/ball on the house side of the cleanout. Then fill the drainage system from the main roof vent. When the inspection's over pull the plug and the extra water wiil drain out in the sewer.
good luck on the inspection, Tom