Sewer smell and noise from new shower drain, but GC insists he put a P-trap

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WallyWater1

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Hi everyone,

I am having a serious issue with my newly remodeled guest house shower. See attached pic.

Every day that I check by turning on the shower, sewer smell comes out from the new shower drain. It also happens when I flush the toilet first, before turning on the shower.

The smell goes away after a couple of minutes, but I still hear from the shower drain all of the water rushing out when the toilet gets flushed, or even the sinks are used.

I have done my best to troubleshoot the issue before we decide to tear up the tile and concrete, at his expense. So far, two independent plumbers told me that the issue is that there is no P-trap.

I want to make sure I have my bases covered before having him start demolition. So here are my questions.

1. How do I confirm with 100% certainty the presence of a P-trap?

2. If there is a P-trap there, could a venting issue be the cause? I did not see him add a vent between the new shower drain and where the old shower drain was.

3. Could the vent that services the old shower drain, and therefore the new shower drain, be clogged and need to be flushed?

4. Finally, if he did not remove the P-trap below the old shower, could the presence of the additional P-trap under the new shower drain create an S-trap situation I have been hearing about, even though they are fairly far apart?

I am meeting with him tomorrow.
 

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If you hear the toilets and sinks drain through the shower drain then you may not have a Ptrap or it may not be holding water.

Anything gurgling or backing up ?
 
No P-trap seems to be the consensus so far.

What is the easiest way to confirm that there is no P-trap there?
 
Twowaxhack said:
If you hear the toilets and sinks drain through the shower drain then you may not have a Ptrap or it may not be holding water.

Anything gurgling or backing up ?
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No gurgling I would say, and no backing up.

Just the wooshing sound of water whenever the toilet is flushed or the sinks are used.
 
From what you’ve told me would be proof enough for me. Especially after I heard it myself.

You could do a smoke or peppermint test.
 
You could simply look. Take the strainer off of the drain hole and look into it. You should see water. If you see just the inside of a bottom of a piece of pipe with no water (or a very tiny amount of water) then the trap either doesn't exist or is wrong. You should see a tube full of water unless the tailpiece is offset.
 
Why are you letting a gc do plumbing?

I'd be surprised if the judge didn't say it was your own fault for having an unlicensed person do your plumbing.
 
JG plumbing said:
You could simply look. Take the strainer off of the drain hole and look into it. You should see water. If you see just the inside of a bottom of a piece of pipe with no water (or a very tiny amount of water) then the trap either doesn't exist or is wrong. You should see a tube full of water unless the tailpiece is offset.
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That was my confusion about being able to see the water, easily from the drain. In my other shower, which was expanded too, I was not able to see any water at the bottom but I have never gotten any sewer smell there. So it looks like the plumber I used then did it right, and offset the tailpiece and made sure to put a P-trap in.
 
JG plumbing said:
You could simply look. Take the strainer off of the drain hole and look into it. You should see water. If you see just the inside of a bottom of a piece of pipe with no water (or a very tiny amount of water) then the trap either doesn't exist or is wrong. You should see a tube full of water unless the tailpiece is offset.
Click to expand...
In the shower drain with the issue, he would have had no good reason to do an offset, since he dug up concrete all the way to the new shower drain area. His line is that "he puts P-traps in all of his showers." From what I can see, the water just seems to flow straight towards the old shower drain.
 
JG plumbing said:
2 p traps wouldn't be causing this.

Vent clogged could, no vent could.
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I reviewed my pictures from the demolition, and added details to the picture I attached.

My concern now is that "no vent could."

The old shower had a white PVC pipe behind it connected to the large vent stack in the wall, where the new shower door sits.

The GC ran a drain pipe straight to the old spot, and did not demo concrete anywhere else.

So if he did indeed put a P-trap there, would this mean that no venting is the cause?
 

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Yes it could be the cause.

The important thing... and I don't know why you can't verify this...look into the drain for the trap. If you have a trap and it's being siphoned and it's the correct size it's likley a venting issue.
 
Even if he hooked it up with a trap the vent needs to be the correct distance from the trap. That also could be it.
 
JG plumbing said:
Yes it could be the cause.

The important thing... and I don't know why you can't verify this...look into the drain for the trap. If you have a trap and it's being siphoned and it's the correct size it's likley a venting issue.
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Will double-verify with a borrowed snake camera tomorrow. At the moment I cannot see water at the bottom. And no water seems to be holding after I just use the shower.

And then for all that, it looks like no venting at all. Yuck. Can't take contractor recommendations at face value.
 
Someone can run a camera down the drain.

If the p trap is not right under the drain, it should be very close by.

The camera will go fully underwater to prove the trap exists, and is full of water.

You might want to run a slow trickle of water for a minute or so before the camera test, to fill up the trap, in case it is being sucked dry by poor venting or some other problem.

Then you can flush the toilet and see if the trap gets sucked dry, or run the shower at full volume for a few minutes, to also see if that sucks it dry.

Also run any nearby fixtures like a sink, also in nearby bathrooms.

There could be a venting issue nearby, and another nearby fixture is starved for vent air, and it takes it from the shower drain instead.
 
Jeff Handy said:
Someone can run a camera down the drain.

If the p trap is not right under the drain, it should be very close by.

The camera will go fully underwater to prove the trap exists, and is full of water.

You might want to run a slow trickle of water for a minute or so before the camera test, to fill up the trap, in case it is being sucked dry by poor venting or some other problem.

Then you can flush the toilet and see if the trap gets sucked dry, or run the shower at full volume for a few minutes, to also see if that sucks it dry.

Also run any nearby fixtures like a sink, also in nearby bathrooms.

There could be a venting issue nearby, and another nearby fixture is starved for vent air, and it takes it from the shower drain instead.
Click to expand...
Confirmed two things today. One, that the P-trap installed is offset. Two, that there is no venting AT ALL for the shower drain after the P-trap.

Is this officially the cause of my sewer gas issue?
 
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