Dried drain smell?

I was looking at a house today with my sister.  The place was pretty nice but it had an odd smell, not necessarily of a sewer but something more like a paper mill (but not as intense).  We asked the realtor about it and she said that the house had been empty for a long time and the u bends in the drains had dried up.

Is this a plausible explanation?


Was the smell more noticeable in kitchen/bathrooms?


drummerboy said:

Was the smell more noticeable in kitchen/bathrooms?

 Not really.  It wasn't localized.  Of course, the place had an open floor plan with the kitchen and the bathroom doors were all opened.  That said.....


Anyway, it sounds like a reasonable explanation. If the u-bends (traps), dried up, then you'd get sewer gas coming through the pipes, but since the house hadn't been used in a while, there wouldn't be anything in the pipes to be really stinky. I think.

Did the realtor run some water to fill the traps?

We used to have multiple plumbers posting on MOL. Where'd they all go?


Dried up drain u-bends would allow gasses to come back up into the house. It wouldn't matter if anyone used the toilets recently ... the gas comes up from the sewer system. 


mrincredible said:

Dried up drain u-bends would allow gasses to come back up into the house. It wouldn't matter if anyone used the toilets recently ... the gas comes up from the sewer system. 

Well yeah, but think about it for a minute. If the house hadn't been used in a long time, the distance between your nose and the real stinky gunk could be a couple of hundred feet, instead of like ten. That's got to make a difference in the dissipation of it's olfactory influence.


mrincredible said:

Dried up drain u-bends would allow gasses to come back up into the house. It wouldn't matter if anyone used the toilets recently ... the gas comes up from the sewer system. 

 This ^^.  Sanitary sewer gasses will enter through dried up traps.  The gasses can come from the house lines or even the town's sanitary sewer line.  Running water through all of the plumbing fixtures should prevent any more gas from entering the house.  You will still need to air the house out though.  Also, look to see if there is a floor drain tapped illegally in to the sanitary sewer line, or if there is a clean out cap off, loose, or holes drilled in the cap or pipe.  These are also ways for the gasses to enter the house.


drummerboy said:

Well yeah, but think about it for a minute. If the house hadn't been used in a long time, the distance between your nose and the real stinky gunk could be a couple of hundred feet, instead of like ten. That's got to make a difference in the dissipation of it's olfactory influence.

 Nope. It just stinks. The sewer system is full of nasty gas through and through.


mrincredible said:

drummerboy said:

Well yeah, but think about it for a minute. If the house hadn't been used in a long time, the distance between your nose and the real stinky gunk could be a couple of hundred feet, instead of like ten. That's got to make a difference in the dissipation of it's olfactory influence.

 Nope. It just stinks. The sewer system is full of nasty gas through and through.

wrongo. re-read the opening post. the smell was faint and not even clearly sewer gas. Because of the dissipation of the olfactory influence.

Don't make me draw a diagram.



drummerboy said:

wrongo. re-read the opening post. the smell was faint and not even clearly sewer gas. Because of the dissipation of the olfactory influence.

Don't make me draw a diagram.

 Sometimes I think you just like to argue about everything all of the time.  I don't know how much time you have spent working in the trades, or dealing with empty P traps, but I can tell you that you are coming across pretty poorly right now.  This problem can absolutely, 100%, be caused by dried out P traps.  Fill the traps, air the place out, and move on.


FilmCarp said:


drummerboy said:

wrongo. re-read the opening post. the smell was faint and not even clearly sewer gas. Because of the dissipation of the olfactory influence.

Don't make me draw a diagram.

 Sometimes I think you just like to argue about everything all of the time.  I don't know how much time you have spent working in the trades, or dealing with empty P traps, but I can tell you that you are coming across pretty poorly right now.  This problem can absolutely, 100%, be caused by dried out P traps.  Fill the traps, air the place out, and move on.

You are misunderstanding me. All I'm saying is that the smell would be faint because the sewer pipe is probably dried up all the way up to where it hits the street sanitary line.

I never said anything about dried up traps not allowing the smell to come in. Just the opposite in fact.

So, frankly, I'm not sure what you're talking about.

ETA: I grew up in house where I very rarely saw a plumber or electrician or carpenter or any other tradesman. My dad did it almost all by himself - with my help, as needed - and consequently I learned an awful lot about the trades.


FilmCarp said:

Sometimes I think you just like to argue about everything all of the time. I don't know how much time you have spent working in the trades, or dealing with empty P traps, but I can tell you that you are coming across pretty poorly right now. This problem can absolutely, 100%, be caused by dried out P traps. Fill the traps, air the place out, and move on.

A friend once wrote a book about the Mid-American Conference and its reputation for being “the Cradle of Coaches.” That’s where I first came across the aphorism “He doesn’t know what he doesn’t know,” which was how rival football coaches of the time described Bo Schembechler. It took me a while to figure out what that meant, but years later, as I observe and participate in online discussions, it keeps coming back to me.

Then again, I’m not a plumber, so what do I know.


DaveSchmidt said:

FilmCarp said:

Sometimes I think you just like to argue about everything all of the time. I don't know how much time you have spent working in the trades, or dealing with empty P traps, but I can tell you that you are coming across pretty poorly right now. This problem can absolutely, 100%, be caused by dried out P traps. Fill the traps, air the place out, and move on.

A friend once wrote a book about the Mid-American Conference and its reputation for being “the Cradle of Coaches.” That’s where I first came across the aphorism “He doesn’t know what he doesn’t know,” which was how rival football coaches of the time described Bo Schemblechler. It took me a while to figure out what that meant, but years later, as I observe and participate in online discussions, it keeps coming back to me.

Then again, I’m not a plumber, so what do I know.

 But in this case, I happen to know what I'm talking about.

Others, however, seem to have reading comprehension problems.


drummerboy said:

Others, however, seem to have reading comprehension problems.

Count me among them, because I failed to make the connection between “not as intense as a paper mill” and “faint.”


DaveSchmidt said:

drummerboy said:

Others, however, seem to have reading comprehension problems.

Count me among them, because I failed to make the connection between “not as intense as a paper mill” and “faint.”

dude - he couldn't identify it as a sewer smell. Either it's because the smell was faint - or it had been transmogrified into some other odor by evil forces. Or perhaps, by a hundred feet of dried up sewer pipe.

Or perhaps the realtor was such a nitwit as to show a house that had the rank (non-faint) smell of sewage. Yeah, maybe that's it.



drummerboy said:

Or perhaps, by a hundred feet of dried up sewer pipe.

See, that’s my third disadvantage: not a plumber, reading miscomprehension, and my house is only 10 feet from the street.

ETA: Anyway, to the OP’s original question, there appears to be consensus agreement that the answer is yes.


It is a weird smell.  My sister thought it might be natural gas but I have a fair amount of experience with that scent and I didn't see it.  It really reminded me a bit of a paper mill. No sign of water damage anywhere in the house.


Probably the best way to remove any question about the sewer smell is make sure all the drains have some water flushed through them and then open up some windows to let to house air out for a little while. Then close the windows and see if the smell comes back. If the house has been empty for a while as you say it's important to make sure to find all the possible drains, including a sump pump or basement toilet.

Any other clues about possible sources of the smell? Is there any recent work, like drywall work? That can smell a little like wet paper. Was the house full of junk at some point that could have gotten wet and been cleaned up? I'm thinking like old newspaper or cardboard boxes in the basement... that sorta thing.




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