Occam’s plumber
March 20, 2016 1:41 PM Subscribe
Plumber cleared kitchen sink drain; then basement flooded. Test my theory?
Last Monday our kitchen sink backed up, and a plumber used a long snake to clear the drain. All good, it appeared. But a few days later, in the basement, we discovered that the outbound PVC kitchen pipe had lifted up from its joint with the vertical iron pipe that leads out to the sewer. Here’s a pic – hard to see, but the PVC is loose and there’s a gap.
The PVC still dropped its contents into the iron pipe, but the latter was backing up, via the new gap, onto the floor. That’s because there was a blockage a foot or 2 down. Thanks to a second visit from the same company, which I paid for, all is clear now, the pipes reattached, and the sink flows fine.
Something lifted that PVC pipe free. Could it have been the first plumber’s snake? That would have let the sink flow freely, leading him to think he had cleared the blockage. But it was flowing freely onto the basement floor, out of his sight, and in fact the blockage remained.
If that’s what happened, the plumbing company caused the problem and we’ll have them make us whole for the second visit, damage, and clean-up. But how likely is it? Is there a better explanation?
The second plumber told us the bands were loose, and the head pressure from the 2-foot-column of water above the blockage separated the pipes.
YANML, YANMP. But your thoughts are appreciated.
Last Monday our kitchen sink backed up, and a plumber used a long snake to clear the drain. All good, it appeared. But a few days later, in the basement, we discovered that the outbound PVC kitchen pipe had lifted up from its joint with the vertical iron pipe that leads out to the sewer. Here’s a pic – hard to see, but the PVC is loose and there’s a gap.
The PVC still dropped its contents into the iron pipe, but the latter was backing up, via the new gap, onto the floor. That’s because there was a blockage a foot or 2 down. Thanks to a second visit from the same company, which I paid for, all is clear now, the pipes reattached, and the sink flows fine.
Something lifted that PVC pipe free. Could it have been the first plumber’s snake? That would have let the sink flow freely, leading him to think he had cleared the blockage. But it was flowing freely onto the basement floor, out of his sight, and in fact the blockage remained.
If that’s what happened, the plumbing company caused the problem and we’ll have them make us whole for the second visit, damage, and clean-up. But how likely is it? Is there a better explanation?
The second plumber told us the bands were loose, and the head pressure from the 2-foot-column of water above the blockage separated the pipes.
YANML, YANMP. But your thoughts are appreciated.
Read the fine print on your receipt from the first plumber. I'm sure that there is a liability release, or a binding arbitration clause, or something like that. I doubt that you'll be made whole for the water damage.
No, two feet of head (hydraulic pressure) is about 1 PSI, and it is not going to make a pipe lift out of a coupling. That's *nonsense*. Hydraulic pressure is not directional. How was it going to develop a directional force, to rocket out of the coupling, when it's pressing in all directions at once?
Yes, the first plumbers snake could have lifted the PVC pipe out of the coupling.
It could have happened after the plumber had gotten the snake as far as they could into the pipe. When the plumber pulled, the friction of the snake inside the plastic pipe around bends could cause the pipe to lift, especially if the pipe sections are not well anchored between the snake entry point in the wall (he removed the trap to snake the drain, right?) and the rubber coupling.
You could recreate the situation and demonstrate it to any who will look. Insert a snake as far as it will go. Position an observer in the basement. Pull on the snake. Watch the motion of the white pipe.
posted by the Real Dan at 4:10 PM on March 20, 2016 [2 favorites]
No, two feet of head (hydraulic pressure) is about 1 PSI, and it is not going to make a pipe lift out of a coupling. That's *nonsense*. Hydraulic pressure is not directional. How was it going to develop a directional force, to rocket out of the coupling, when it's pressing in all directions at once?
Yes, the first plumbers snake could have lifted the PVC pipe out of the coupling.
It could have happened after the plumber had gotten the snake as far as they could into the pipe. When the plumber pulled, the friction of the snake inside the plastic pipe around bends could cause the pipe to lift, especially if the pipe sections are not well anchored between the snake entry point in the wall (he removed the trap to snake the drain, right?) and the rubber coupling.
You could recreate the situation and demonstrate it to any who will look. Insert a snake as far as it will go. Position an observer in the basement. Pull on the snake. Watch the motion of the white pipe.
posted by the Real Dan at 4:10 PM on March 20, 2016 [2 favorites]
Something lifted that PVC pipe free. Could it have been the first plumber’s snake? That would have let the sink flow freely, leading him to think he had cleared the blockage. But it was flowing freely onto the basement floor, out of his sight, and in fact the blockage remained.
Yes, and yes.
...the plumbing company caused the problem and we’ll have them make us whole for the second visit, damage, and clean-up. But how likely is it? Is there a better explanation?
What problem? "Make you whole"? Dial back the hyperbole.
Very likely that's what happened.
You owe the plumbers for the time they were there to completely fix your plumbing problem, period.
posted by humboldt32 at 5:18 PM on March 20, 2016
Yes, and yes.
...the plumbing company caused the problem and we’ll have them make us whole for the second visit, damage, and clean-up. But how likely is it? Is there a better explanation?
What problem? "Make you whole"? Dial back the hyperbole.
Very likely that's what happened.
You owe the plumbers for the time they were there to completely fix your plumbing problem, period.
posted by humboldt32 at 5:18 PM on March 20, 2016
Snaking is an inherently risky activity and the plumber's contract probably makes it clear that they have no control over damage caused by the snake. It's always possible when snaking a pipe that it punches through the pipe at some point. Especially in the case of potentially sketchy repairs.
And while the snake may have pulled apart the joint it is also possible that the snake merely dislodged something blocking the separation.
Those clamps should not dislodge merely from the force of a snake if installed properly. I'd bet there is a substantial gap between the ends of the cast and ABS pipes (should be 1/2" max); and/or that the ABS pipe was not secured in an adequate manner allowing it to move up and down. IE: poor installation was a significant contributor if not wholly responsible for the flood. The plumber mentioned loose clamps which can also be a problem.
I don't think the plumber really owes you anything however if they charged you two call out fees you might want to see if they'd reimburse you for one of them.
posted by Mitheral at 5:30 PM on March 20, 2016 [1 favorite]
And while the snake may have pulled apart the joint it is also possible that the snake merely dislodged something blocking the separation.
Those clamps should not dislodge merely from the force of a snake if installed properly. I'd bet there is a substantial gap between the ends of the cast and ABS pipes (should be 1/2" max); and/or that the ABS pipe was not secured in an adequate manner allowing it to move up and down. IE: poor installation was a significant contributor if not wholly responsible for the flood. The plumber mentioned loose clamps which can also be a problem.
I don't think the plumber really owes you anything however if they charged you two call out fees you might want to see if they'd reimburse you for one of them.
posted by Mitheral at 5:30 PM on March 20, 2016 [1 favorite]
Pulling the snake out, it *could* have caught the rim of the PVC and pulled it loose. But. The PVC should be secured such that there is no play, it should not be able to be moved up and down that much that it would pull out of the coupling. Also if the coupling was loose it would have leaked before. Those couplings should be tight enough that pulling it apart would take significant force... And the pipe should have been braced/supported against the action of such force.
It's a pickle and I don't think you can easily prove anything. Be glad it wasn't a sewer line.
posted by From Bklyn at 9:17 PM on March 20, 2016 [1 favorite]
It's a pickle and I don't think you can easily prove anything. Be glad it wasn't a sewer line.
posted by From Bklyn at 9:17 PM on March 20, 2016 [1 favorite]
Those rubber couplings are not an ideal way to join drainpipes together. Over time, two things happen: the rubber hardens, and the pressure of the clamps on the PVC pipe causes the PVC to creep and dent. If you take the rubber coupling off and look at the end of the PVC under where the clamp was, I bet you'll find it's actually a few millimetres smaller than it was when it was new.
Those two effects together have the effect of substantially loosening the rubber's grip on the PVC and making the band around the PVC get slack; the band hasn't actually expanded, but everything it contains has shrunk.
So if that coupling has been in place for a few years, I think it's completely plausible that a snake being withdrawn through that joint could catch the edge of the PVC and pull it partly apart.
I also don't think that if that happened, it could reasonably be held to be the first plumber's fault.
As for the head pressure theory: if I understand correctly, the blockage the second plumber found was two feet below the rubber joint. The head pressure seen by the joint, then, would not be that of a two foot water column - that would be the pressure seen by the blockage if the top of the water column is right at the joint.
But the joint is in your basement, and if there's water backed up all the way up to your sink from a blockage below that joint, that's easily enough head pressure to force water out through a rubber joint loosened by age, rubber hardening and PVC creep under compression even assuming the upper pipe never actually lifted out of the rubber coupling.
It would pay you to check that coupling every year or so, and wind the screw on the upper band a little tighter. Because it will slacken over time.
posted by flabdablet at 2:15 AM on March 21, 2016 [1 favorite]
Those two effects together have the effect of substantially loosening the rubber's grip on the PVC and making the band around the PVC get slack; the band hasn't actually expanded, but everything it contains has shrunk.
So if that coupling has been in place for a few years, I think it's completely plausible that a snake being withdrawn through that joint could catch the edge of the PVC and pull it partly apart.
I also don't think that if that happened, it could reasonably be held to be the first plumber's fault.
As for the head pressure theory: if I understand correctly, the blockage the second plumber found was two feet below the rubber joint. The head pressure seen by the joint, then, would not be that of a two foot water column - that would be the pressure seen by the blockage if the top of the water column is right at the joint.
But the joint is in your basement, and if there's water backed up all the way up to your sink from a blockage below that joint, that's easily enough head pressure to force water out through a rubber joint loosened by age, rubber hardening and PVC creep under compression even assuming the upper pipe never actually lifted out of the rubber coupling.
It would pay you to check that coupling every year or so, and wind the screw on the upper band a little tighter. Because it will slacken over time.
posted by flabdablet at 2:15 AM on March 21, 2016 [1 favorite]
@humboldt ..
Where's the hyperbole? "Make whole" means reimburse. OP may not be entitled to reimbursement, but it was a reasonable question, and it has drawn some knowledgeable answers.
posted by LonnieK at 4:22 AM on March 21, 2016
Where's the hyperbole? "Make whole" means reimburse. OP may not be entitled to reimbursement, but it was a reasonable question, and it has drawn some knowledgeable answers.
posted by LonnieK at 4:22 AM on March 21, 2016
Response by poster: Well .. not the answer we wanted, but the answers we needed. Seems most likely the connection was weak to begin with. We'll def maintain it going forward, as suggested. Thanks to all.
posted by SallyHitMeOntheHead at 4:52 AM on March 21, 2016
posted by SallyHitMeOntheHead at 4:52 AM on March 21, 2016
Did the plumbing company visually inspect the pipes after snaking them out? Snaking is a pretty vigorous mechanical process and always has the potential to damage pipes. It would/should be a pretty normal post-snaking procedure, to go down and visually inspect any pipes that are easily visible for damage afterwards.
That's a pretty reasonable question to ask your plumbing company, anyway.
posted by flug at 9:14 AM on March 21, 2016
That's a pretty reasonable question to ask your plumbing company, anyway.
posted by flug at 9:14 AM on March 21, 2016
This thread is closed to new comments.
posted by bonobothegreat at 2:54 PM on March 20, 2016