I cut into the vertical cast iron soil stack in my basement to make a repair. When the pipe was open I was getting a bit of drippage from the pipe... enough I had to put a bucket down to catch it. Probably caught less than a quarter of a gallon during the hour or so the pipe was open.

It got me to thinking, where is this water coming from?

Is some residual water normal?

I had last flushed a toilet and ran sink water about 15-20 minutes prior to cutting into the pipe. No sinks are leaking. Then I thought today maybe its a leaky toilet, but I don't hear it running ever... I even put beet juice in the tank and left it for about 2 hours today with nothing trickled into the bowl.

what do you think?



Edited 2 times.

it is most likely residual water caught in all the corrosion and buildup in the lines. When water runs down vertical pipes, it doesn't fall through the center, it coats the sides, it may even be condensation from an AC unit depending on the location.

i find that the toilet is usually the culprit.