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Unclev 03-02-2012 06:30 PM

Main ABS Drain Pipe Leakage
1 Attachment(s)
Hello all,
I have a leak in my main drain stack. The water seems to be starting at the base of the 3 " ABS pipe joint that is right between the basement and the first floor (subfloor). The water leak is on the backside against the drywall (firewall). I have almost zero access to the area in the corner behind the pipe to see if is originating at that joint or if it is coming from above. It only leaks when I run water down the drain from either the sink or the toilet on the second floor. Both are tied into this drain. I'm confident it is not coming from any higher than the second floor since it does not leak when there is heavy rain. To troubleshoot I have wrapped string and paper towels around the pipe an inch higher than the joint to see if it would get wet. It doesn't seem to get wet so that would indicate a leak at the joint. Problem is... correct me if I'm wrong but a joint like this usually won't show leakage under normal use. Does anyone have any other troubleshooting methods to prove 100% that the leak is occurring at that joint or possibly higher up. Finally, if the leak is indeed at that joint and I cut the main drain stack 2 or 3 inches higher than that joint would the main drain stack remain stable and intact for a repair or for a lack of better words come crashing down? Any help and guidance would be greatly appreciated.

plummen 03-02-2012 07:01 PM

Trim the wood out around the pipe :)

JeepNick 03-02-2012 07:01 PM

Find your cleanout and use an inflatable plug to stop all drainage. Close all your drains up tight and perform either a water mast test or a peppermint test on the whole DWV system. Either method should help you locate the exact point of the leak.

Homerepairguy 03-02-2012 07:06 PM

Looking at the picture you posted, there are screws or nails coming through the vertical metal piece just below the ABS pipe. I bet there are one or more screws or nails puncturing the ABS pipe.

My guess anyway,

Unclev 03-03-2012 10:50 AM

Thank you for all the replies. I have googled the peppermint test and now understand what to do there but I didn't get info on a "water mast test". JeepNick, any help on how to perform this would be greatly appreciated.

TheEplumber 03-03-2012 11:55 AM

199 Attachment(s)
I would try to locate the leak without the water test. The stack test involves capping all fixture outlets and plugging main drain then filling system with water.
Remove more material around the pipe and use an inspection mirror. Start running water at the lowest fixture on that stack and work your way up. I suspect that the backside of that 45 didn't get glued well due to it's location against the wall. It has now failed.

Unclev 03-03-2012 01:36 PM

I personally think the leak is at that joint as well. What I don't understand is how it is physically possible if the pipe on the top is actually fitted into the elbow and it is running vertically. I can see if this pipe was running horizontally. Please help me understand how this leak at that joint could possibly exist. Once again thank you for everyone's input.

TheEplumber 03-03-2012 02:01 PM

199 Attachment(s)
I'm only guessing, but 3" is typical for toilets and the lav wet vents into the 3" line above the toilet branch. So I'm wondering if you have a tee in the joist area. If so, the bottom of the tee maybe leaking and running down to the hub of the 45.

plummen 03-03-2012 06:03 PM

No matter how you test it I think you need to open area around pipe to see it :)

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