Rough plumbing = sewer gas

[mattt19]

The rough plumbing has just been completed for my bath remodel. The vent stack for this bath is shared with an adjacent bathroom. A day after the rough plumbing was completed I could smell sewer gas coming out of the adjacent bathroom's sink. The drain lines in the remodeled bath had rags stuffed into the open drain lines. I placed plastic bags over the open drains and taped them on. This appeared to take care of the problem. Now a week later the smell is back. I've left a message with the plumber. Does anyone have an idea why I would be smelling sewer gas?

[krow]

Without seeing what was done and in what condition/stage that the project was left at, there is no way to tell. The traps may be drying out or empty or you have not sealed/capped one of the pipes adequetly.

[mattt19]

The entire bathroom was re-plumbed. The toilet, vanity and tub were all moved. New water lines and drain lines were installed. At this stage the plumber is waiting for all the finish work to be completed (tile, drywall...) How would you even go about determining what is causing the problem? Would a hole in a pipe cause this? I rechecked the pipes and they all appear sealed tightly. I only smell this in the adjacent bathroom. This bathroom is used on a daily basis so there should be water in the traps.
This problem comes and goes. This morning I could smell it, now I don't. There isn't a predictable pattern to when it smells or not. It's random.

[krow]

Would a hole in a pipe cause this? . Thats very possible. A cracked fitting may very well be a problem. It usually happens with ABS fittings. I haven't come across any pvc doing this


If you have a shower in the new bathroom, check the drain for the shower and see if the trap is full of water.


Just a thought off the wall. I had an incident where a strange odour was comming from a clients bathroom. It turned out to be the wiring in a pot light when it started heating up. It wasn't melting or anything like that, but it was a concern , enough to replace the pot light.

[AZ Contractor]

It sounds like it could be incorrectly vented and its causing the trap to be siphoned dry.

[mattt19]

The plumber stopped by today but couldn't find anything wrong. There are no traps yet in the new bathroom. Just the rough drain lines. These are sealed.
If it was incorrectly vented, causing the traps to be siphoned dry, wouldn't the trap always be dry? He's been a plumber for 40 years so I hope he vented it correctly.
If there is a cracked fitting how would I find it? He checked all the fittings and said they looked OK. Could I pour water through the drains and see if any of the fittings leaked?
Hopefully I can solve this before the floor goes down and the walls are sealed up.

[crater]

Are the drains that you have covered with plastic bags the stub-in's or actual drains like the tub or shower?
If they are in use, then there should be traps for them, and if the gas is coming from them, then you have some incorrect plumbing, something like the toilet is flushing past the drain pulling the water out of the trap. If there just stub's, then you can buy cheap knock out plugs that you glue into the pvc, that should stop gas from coming in. I saw a coupling once that wasn't glued. We as a quick fix (not permanant) sopped the exterior of the joints with pvc glue, when we fixed for good we had to cut out the couple and replace with a rubber coupling, it was a pain in the rear.

[hj]

After he installed the piping it should have been tested with a head of water to ensure that there were no leaks or bad fittings. Odors are the hardest problem to diagnose because they can originate a long way from where you have the problem.

[mattt19]

Are the drains that you have covered with plastic bags the stub-in's or actual drains like the tub or shower?


They're stub-in's. The problem (the smell) isn't in the bathroom that's under construction. The smell is coming from the sink in the adjacent bathroom. Prior to this there wasn't a smell. It's only the sink that smells periodically. The shower and toilet in the same room don't.

"After he installed the piping it should have been tested with a head of water to ensure that there were no leaks or bad fittings."

The pipes were tested but not the drain lines ( is that what you mean?)

[krow]

The smell is coming from the sink in the adjacent bathroom. Prior to this there wasn't a smell. It's only the sink that smells periodically. The shower and toilet in the same room don't.

If the trap is fine, I'm going to bet that the sink overflow/P.O. plug is filled with gunk. I've been told that some baking soda and vinigar may help clean that smell up. (I've never tried that myself)

[mattt19]

Thanks,

I'll try that

[mattt19]

Well, the smell is back. When the plumber checked the pipes he also removed the stopper in the sink and cleaned out all the gunk that was attached to it. After that the smell went away and I assumed that was the problem. When the smell came back I tried using vinegar and baking soda as recommended. That didn't work. I can only smell the odor when water is running down the drain though my wife smells it at other times.
The last time I smelled the odor I removed the trap. It was full of water.
I'm posting pictures of the sink and the plumbing.


Thanks,

Matt

[master plumber mark]

it looks ok, a little sloppy but
it will work for a hundred years...

what probably happenned to you is
most likely during construction some long hair or string
or debris got stuck half way around that sink trap

and when this happens , it has atendencey to
act like a siphon hose and literaly drain that trap dry..

its really no big deal, it happens a lot
so occasionally you might
want to pour some boiling water down that
sink to loosen debris out of it...

[Terry]

A little sloppy waste and vents?
That work looks like someone that just opened a book for the first time and couldn't understand it.

The trap arm for the lav should go up at a 2% rise, or 1/4" per foot.
He has raised it with fittings, creating an "S" trap what will siphon the trap dry.

[mattt19]

Hi Terry,

Which part is the trap arm? Is it the chrome piece leading from the trap to the wall? I put a level on it and it is angled up (maybe the angle of the photo looks like it's not). If the trap itself is on incorrect that would be my fault. I took it off to see if there was water in the trap.
I don't know anything about the quality of the work. He did do the plumbing for the sink in the first picture. He had to tie into the existing system. In the picture with the exposed plumbing, there had been a sink in this area which he had to work around when doing the plumbing for the first sink. There are also a number of pipes under the wall in this area including a gas line that couldn't be moved. I don't know if any of this contributed to the quality of the work. Are there any obvious problems that I should have corrected? Or is it just the case of sloppy work that looks bad but will function fine.
I'm open to recommendations if anyone can recommend a good plumber in Los Angeles.

Thanks,

Matt

[Terry]

Matt,
In the picture of the black pipes, you have it labeled "sink drain".
That pipe should be straight, and the santee raised.

[Redwood]

Your sink drain needs to be redone more like the pink lines I drew over your picture. The pitch should be 1/4" per foot. Going the way he has it made an s-trap which is illegal.

http://i44.photobucket.com/albums/f2/Redwood39/sink_back.jpg

[hj]

IT is not only illegal but it will siphon itself when the water flow is just right. He must have forgotten what he learned in his first week after 40 years.

[mattt19]

Hi everyone,

Thanks for the information. It's not what I wanted to hear. I'm having real doubts about the plumber because of this. He's had two chances to catch it and missed it both times.
In his defense, I don't know if he installed this section of plumbing or if it was existing. It's possible he just hooked the sink to it. There had been a sink there previously so it's possible someone else did this. Why he didn't notice it I don't know. The bathroom was gutted down to the studs so he should have seen it. It certainly explains the sewer smell. If I have him fix it, in your opinion, whose responsibility is it? Should I be expected to pay for it?
If I fix it, I have a couple questions. I'd cut the pipe at 1,2 and 3 and remove the S. At # 1 I'd be left with 2 1/2" of pipe. I'd attach a coupling to this and then a length of pipe that would run to a new sanity tee. The pipe would pitch down 1/4" from point #1 to where it connected to the sanitary tee. The tee would be installed on the drain/vent pipe. What is the flange on the pipe at #2. Do I need this?

Thanks

[krow]

The flange part at #2 is a reducing bushing (2"x 1 1/2"). I can't judge the exact sizes, but it looks like a 2x2x1 1/2 sani T with bushings to reduce to the appropriate sizes. Your branch to the sink looks like 1 1/4" . This drain looks like its wet venting the toilet drain.

You will need a 2x1 1/2 x 1 1/4 sanitary T (or facsimilie)

[statjunk]

Can you guys explain to me why that section would siphon the line?

Is it because there is too much slope in the pipe?

This is a great thread.

Thanks

Tom

[krow]

Is it because there is too much slope in the pipe?
Yes, you are only allowed no more that one pipe diametre graduale slope from the weir of the trap to the vent. In this case it would be 1 1/4" (2% slope or 1/4" per foot)

[mattt19]

I can't figure out how to cut the line and attach a new section of pipe. The copper supply line in the photo is tight against the section of pipe. If I cut it where the pipe joins the fitting I'll be unable to attach a new fitting to this section of the pipe. Nothing wider than 1 1/2" pipe will fit between the wall and supply line. Is it possible to remove the pipe from the fitting that passes through the wall? Is there any other solution to this?

[statjunk]

You can cut the copper and get it out of the way. Then put it all back together.

Tom

[MG]

Get a Sawzall...as you'll be cutting out that entire funky section AND the sanitary tee its going to be joining into, along with some of the vertical so you can move up the tee into the right position. The blade length of the Sawzall should give you the room to work around that copper.

[mattt19]

The blade length of the Sawzall should give you the room to work around that copper.

I don't have a problem cutting the pipe. The problem is that I can't slide anything thicker than 1 1/2" past the pipe. If I cut this small section of pipe,either before or after the copper pipe, I won't be able to put a coupling on the remaining piece. The coupling would be to big to fit behind the supply line.

I don't want to remove the copper pipe. I'm not a plumber and this is beyond what I feel comfortable doing. If that's the only solution than I either have to have the original plumber correct this (he missed it the first time when it would have been easy to correct) or find a new one.

I'm hoping there's a way to do this that I'm overlooking.

Thanks

[MG]

If that lav is behind the wall as close as I think it is, I'd cut everything out to the sanitary tee including the 90 degree bend to the lav. Once you have all that out you should be able to get a 1.5" section in there without a problem - it would be a longer section with no coupling. From the pic you posted it looks like there is plenty of room to work around it.

[westcoastplumber]

It looks like the guy installed the santee first, then later, mounted the sink and found out he put it to low.....so he tried to fix it:eek:

I am a licensed, insured plumbing contractor here in los angeles, are you sure you hired the same? that is plumbing 101.

I may know him.......I have seen work like this alot in this area, due to the amount of hack, unlicensed, un-insured "Plumbers" in this area.

One day people will wake up;)

[mattt19]

WCP,

I might give you a call, but first I want to contact the original plumber and see what he says. He's a licensed plumber. I got three bids on the job. they were all within $100 of each other. None were cheap by any means. He spent the most time here and gave a detailed estimate of what he was going to do. Unlike the other two he was the one doing the work, not just the estimate.

MG,

I think you're suggesting removing the entire section, from the sink to the drain/vent pipe, correct? Basically there's no way to do this without re-plumbing the entire sink.

[mattt19]

MG,

I looked at the fittings again. There's a bit of an obstacle with the 90 degree bend. There's no problem removing it but replacing it's a issue. The wall is a mud wall. It's over an inch thick and formed tight around the fitting. I can remove the fitting by cutting it into sections but I wouldn't be able to fit a new fitting through the same hole. The socket will be to big to fit through the hole. Is there any other fitting other than the traditional 1 1/2" coupling that can be used to join the pipes?

[MG]

You'll likely end up having to cut that hole bigger so the hub can make it through.

[westcoastplumber]

WCP,

I might give you a call, but first I want to contact the original plumber and see what he says. He's a licensed plumber. I got three bids on the job. they were all within $100 of each other. None were cheap by any means. He spent the most time here and gave a detailed estimate of what he was going to do. Unlike the other two he was the one doing the work, not just the estimate.

MG,

I think you're suggesting removing the entire section, from the sink to the drain/vent pipe, correct? Basically there's no way to do this without re-plumbing the entire sink.





I can tell you how I would fix it.

First I would cut the 2" drain, and the 11/2" vent, drop the trap and remove the mess that is there, includes cutting out the santee and the 1/4 bend picking up the trap and RE-DO the whole mess.

Sorry, I don't try to work with whats there, it is a mess and to time consuming.

If the tile and mortar is tight against the 1/4 bend, that is wrong anyways, it should not be tight against the pipe, there needs to be room for expansion.

This is what a escusion is used for, so a proper gap is left around the penetration.

[mattt19]

The plumber came out on Friday to look at the line. He confirmed that he put in the trap arm but not the sanitary tee. He curved the trap arm so it would join up with the sanitary tee. I asked him about it being a S trap and being pitched so steep. He doesn't see any problem with the pitch. I showed him the codes but he dismissed them saying the trap wasn't the problem. English is his second language (he's German) so it can be hard to communicate with him.
The sink has never smelled when he's been here.
To him, the fact that the smell isn't constant is an indication that it's not the pitch of the trap arm that's causing the problem. He thinks the smell is from the "gunk" he removed from the drain pipe when he was here before.
He'll fix the trap arm if I want him to but he pointed out several things that could make this problematic. First there's the issue of the supply line hindering access to the arm. He'll cut the line to gain access to the arm and then re-connect the arm. If he does this there's the possibility that the supply line will be proud of the studs (they're 2 by 3's). Second, to cut the sanitary tee he'd need to cut several inches below the bottom of the tee. If you look at the picture you can see that there's blocking an inch below the tee. He'd have to remove some of this to be able to cut the pipe. There's a shower on the other side and he's worried that when he removes the blocking he could damage the shower pan. And lastly, the walls are mud walls. The wall bulges into the cavity conforming to the shape of the pipes. The wall appears to bulge in where the new pipe would run. This would cause the pipe to be proud of the studs. It also possible that it would'nt line up with the new sanitary tee.
I know what he did is wrong and should be corrected (though not by him). Given the potential obstacles in correcting this I'm wondering how bad is the configuration of the trap arm? My understanding of the code is that the trap arm must pitch 1/4" but not more than the diameter of the pipe - 1 1/2" - (please correct me if I'm wrong). The pipe drops 2 1/4" to 2 1/2", making it off by 3/4" to 1". How much off is to much?
I went a year and a half with this configuration of the trap arm without smelling sewer gas. It was about a month after the rough in for the second bath that the sink in the first bath began to smell. Not constantly, but periodically over the span of two weeks. After he cleaned the drain arm there was the faint smell of sewer gas twice. It's been three weeks and I haven't smelled anything. I've tried to duplicate the problem by making the trap siphon without any luck.
The potential problems of installing the new arm and the fact that the drain doesn't smell plus the inability to make the drain siphon dry makes me unsure of what to do.
Any opinions?

Thanks again for all the help and advice.

[mattt19]

The smell of sewer gas was coming from the sink today. The dishwasher had just drained so I assumed that it caused the trap to siphon dry. I removed the trap expecting it to be empty. When I removed the trap there was the unmistakable smell of sewer gas coming from the trap arm but the trap was completely full of water.
Is it possible to smell sewer gas when the trap is full of water ? :confused:

[jadnashua]

Is the sink new or old? The overflow can start to grow some nasties and a good cleaning of the sink's overflow might solve the problem.

[GregO]

You've got that wall opened up, so you now have the perfect opportunity to make it right so you never have to worry about it. I recommend repairing it as Terry and others have pointed out because if you do, you won't have to worry about it down the road. Greg


The plumber came out on Friday to look at the line. He confirmed that he put in the trap arm but not the sanitary tee. He curved the trap arm so it would join up with the sanitary tee. I asked him about it being a S trap and being pitched so steep. He doesn't see any problem with the pitch. I showed him the codes but he dismissed them saying the trap wasn't the problem. English is his second language (he's German) so it can be hard to communicate with him.
The sink has never smelled when he's been here.
To him, the fact that the smell isn't constant is an indication that it's not the pitch of the trap arm that's causing the problem. He thinks the smell is from the "gunk" he removed from the drain pipe when he was here before.
He'll fix the trap arm if I want him to but he pointed out several things that could make this problematic. First there's the issue of the supply line hindering access to the arm. He'll cut the line to gain access to the arm and then re-connect the arm. If he does this there's the possibility that the supply line will be proud of the studs (they're 2 by 3's). Second, to cut the sanitary tee he'd need to cut several inches below the bottom of the tee. If you look at the picture you can see that there's blocking an inch below the tee. He'd have to remove some of this to be able to cut the pipe. There's a shower on the other side and he's worried that when he removes the blocking he could damage the shower pan. And lastly, the walls are mud walls. The wall bulges into the cavity conforming to the shape of the pipes. The wall appears to bulge in where the new pipe would run. This would cause the pipe to be proud of the studs. It also possible that it would'nt line up with the new sanitary tee.
I know what he did is wrong and should be corrected (though not by him). Given the potential obstacles in correcting this I'm wondering how bad is the configuration of the trap arm? My understanding of the code is that the trap arm must pitch 1/4" but not more than the diameter of the pipe - 1 1/2" - (please correct me if I'm wrong). The pipe drops 2 1/4" to 2 1/2", making it off by 3/4" to 1". How much off is to much?
I went a year and a half with this configuration of the trap arm without smelling sewer gas. It was about a month after the rough in for the second bath that the sink in the first bath began to smell. Not constantly, but periodically over the span of two weeks. After he cleaned the drain arm there was the faint smell of sewer gas twice. It's been three weeks and I haven't smelled anything. I've tried to duplicate the problem by making the trap siphon without any luck.
The potential problems of installing the new arm and the fact that the drain doesn't smell plus the inability to make the drain siphon dry makes me unsure of what to do.
Any opinions?

Thanks again for all the help and advice.