Water draining through vent resulting in leak
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Drains go down and vents go up. Gravity unless pumping.
I just remedied a leak in my neighbor's house that may be similar. The builder put a new roof on an old roof to stop a roof leak due to poor whatever. The kitchen sink vent passes through the first roof then the second. It was leaking but not into the living area, just the attic. Pooling on the paper of the insulation during the cold months. So after some looking around and consultation I cut the first roof back to find that the copper vent attached to an Oatey PVC through the roof vent was not properly connected. It is fun.
I just remedied a leak in my neighbor's house that may be similar. The builder put a new roof on an old roof to stop a roof leak due to poor whatever. The kitchen sink vent passes through the first roof then the second. It was leaking but not into the living area, just the attic. Pooling on the paper of the insulation during the cold months. So after some looking around and consultation I cut the first roof back to find that the copper vent attached to an Oatey PVC through the roof vent was not properly connected. It is fun.
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HomeownerJ
New Member
MKS, appreciate the feedback. Originally thought the same. Went in to the attic thinking perhaps the boot seal around the vent had cracked but bone dry in the attic. Went up again during heavy rain. Still nothing. Removed the medicine cabinet in the bathroom and ran the sink faucet to find a leak dripping from the main stack 2 inches below the sink vent and well below the sink drain branch. I know it sounds ridiculous. My pop and I have been scratching our heads on this one for a week. Here’s a pick of where the leak is coming from right below the sink vent. Strange part is, water isn’t backing up the sink! Pic’s upside down. Water is dripping down from the vent branch above. Again, thanks for your feedback!
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HomeownerJ
New Member
*correction - leak is on main stack two inches below drain vent branch and well above sink drain branch
HomeownerJ
New Member
So I’m pretty sure I figured out what’s going on. If you look at the diagram I put together, I noticed today that the horizontal drain line connecting the sink to the main stack doesn’t exist. I couldn’t tell because of all of the insulation but the second floor sink drain connects to the first floor sink drain and then goes to the main stack so my upstairs tenants and I are actually sharing a drain and vent. Their drain is my vent. I think when we are using the water downstairs, we’re creating a vacuum in the stack, so when the upstairs sink is on water is actually being pulled up the vent. Could this be possible or to code? There was an extension put on the house and I have to wonder if this practice is legit. Thanks again for your insight. - J
I think no to both, especially the possible part.
HomeownerJ
New Member
So if water’s not leaking through the boot on the roof, and all fixtures using water are below the leak, how would water be making it up that vent pipe and down the vent stack?
You earlier said this, which does not require water climbing against gravity.
Also, water can flow along the outside of a pipe.
I am not a plumber.
HomeownerJ
New Member
Here’s an updated picture illustrating the wet vent situation I’m dealing with. If we are using the water downstairs while the sink is on upstairs, could this be enough force to create a syphon in the vent pulling water up the vent drain? From what I’ve learned from this forum, wet vents are only allowed on the same floor. i guess for this reason. Curious if anyone else has ever come across something like this before. Any advise on how to correct? Would an air admittance valve at the 90 on the upstairs vent branch help to mitigate the vacuum effect? Or am I completely off the mark?
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Tie a strip of old bedsheet etc around the pipe a few inches above where you think the is. Tie another just under the roof. The purpose is to see if the water is coming from above.
Your diagram does not tell the story to me.
Your diagram does not tell the story to me.
HomeownerJ
New Member
Reach4, I see water dripping down from the PVC connector. This is notated on the diagram above where it reads “water leaking from PVC connector”. Not sure I can add anymore clarity there. Also, there is a picture above of the actual connection of where it’s leaking from. Thanks, J
I think your diagrams say the spot of the leak is higher than the lavatory drain and the water level in the toilet bowl. Yet water is not rising in those. So if there were a blockage causing water to rise, it would rise in the lavatory or toilet bowl.
Water is not going to be sucked up against gravity in a home.
So my suspicion is that water is coming from above, and maybe over the outside of the pipe, hitting the top of the tee fitting, flowing around the back of the tee where you see it. That is why the suggestion of cloth strips -- to intercept the water coming down the back side of the pipe and let it be detected.
If water is not coming from above outside the pipe, that would imply both a blockage in the vent line below the cross, a blockage in both side legs of the cross, and a source of water above inside the piping. That could be rain into the top opening of the pipe, but three blockages? Seems to be highly improbable. Plus, it had not been raining recently.
One potential source of water is that sometimes people drill a hole in a vent and inject condensation from an attic air conditioner. I don't think that is likely in NY. Plus, you would have seen that and mentioned it.
The other source of water would be condensation. For condensation inside the pipe, I would expect the the pipe to be cooler than the air inside. In the winter, I would expect the air in the pipe to be cooler than the pipe. So that seems not so likely, it seems possible.
Usually with PVC, there is a purple primer used during the gluing process. Clear primer exists, and it is possible that was used. Do your other fittings show purple primer? If water is not coming from outside, that means a bad PVC joint that lets unpressurized water flow through. I don't think that is at all common, but I have limited experience.
If you are convinced that the water is coming from inside the pipe through a bad joint, you could try a Leak-B-Gone PVC Repair Ring, or replace the tee. Another option would be to dry the area, build a dam of some sort, and pour epoxy glue to encapsulate the leaky joint. Another option is to use a few layers of good self-fusing silicone tape, topped with another tape that will provide some compression. Scotch 66 or 33+ electrical tape or Scotch #35 Electrical Tape, White pulled moderately tight might be good for the outer wrap. The white would look better.
Water is not going to be sucked up against gravity in a home.
So my suspicion is that water is coming from above, and maybe over the outside of the pipe, hitting the top of the tee fitting, flowing around the back of the tee where you see it. That is why the suggestion of cloth strips -- to intercept the water coming down the back side of the pipe and let it be detected.
If water is not coming from above outside the pipe, that would imply both a blockage in the vent line below the cross, a blockage in both side legs of the cross, and a source of water above inside the piping. That could be rain into the top opening of the pipe, but three blockages? Seems to be highly improbable. Plus, it had not been raining recently.
One potential source of water is that sometimes people drill a hole in a vent and inject condensation from an attic air conditioner. I don't think that is likely in NY. Plus, you would have seen that and mentioned it.
The other source of water would be condensation. For condensation inside the pipe, I would expect the the pipe to be cooler than the air inside. In the winter, I would expect the air in the pipe to be cooler than the pipe. So that seems not so likely, it seems possible.
Usually with PVC, there is a purple primer used during the gluing process. Clear primer exists, and it is possible that was used. Do your other fittings show purple primer? If water is not coming from outside, that means a bad PVC joint that lets unpressurized water flow through. I don't think that is at all common, but I have limited experience.
If you are convinced that the water is coming from inside the pipe through a bad joint, you could try a Leak-B-Gone PVC Repair Ring, or replace the tee. Another option would be to dry the area, build a dam of some sort, and pour epoxy glue to encapsulate the leaky joint. Another option is to use a few layers of good self-fusing silicone tape, topped with another tape that will provide some compression. Scotch 66 or 33+ electrical tape or Scotch #35 Electrical Tape, White pulled moderately tight might be good for the outer wrap. The white would look better.
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HomeownerJ
New Member
Reach4, thanks for the info. Great suggestions. Oddly enough when I turn the sink on I can actually see water dripping out of the PVC connection in that picture I posted which is above the drain. (The pics upside down). To your point, I think the joint was in bad shape. Looks like they used yellow/clear glue and it’s all corroded. I took your advice and sealed with some epoxy but I guess the struggle I have is, how the heck could water be going up that pipe. If there was a blockage inbetween the downstairs sink and the upstairs sink, that would mean I should have a venting issue (which I don’t) and would also mean the upstairs sink should be backing up which it’s not. I hear you loud and clear regarding gravity, but there are no other fixtures, air conditioners or any other appliances using water above that connection. I am totally certain the water is coming from that poor joint when that sink is in use. Again, please don’t think I’m being stubborn but I have to wonder if the odd wet vent setup is causing some type of positive pressure in that upstairs vent branch.
Yes, that seems impossible, but there it is.
RachelRay
New Member
Did you ever find out what the problem was? I have the seemingly same thing with a leak in my vent pipe. I’ve exhausted all possible reasoning.
