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Funky smell in Bathroom

Post in 'DIY and General non-hearth advice' started by TresK3, Feb 24, 2013.

  1. TresK3

    TresK3 Member

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    We have a bathroom in the basement that periodically gets a sewer-gas smell. And yes, I do keep the traps full. Occasionally I even pour bleach down them. We use the bathroom fairly regularly, so sufficient water flows through the pipes

    I don't believe the bathroom was original to the house, but it's probably been there a good 20+ years. The bathroom has a sink, toilet, and shower. We have new-ish (10 year old) a septic system. The smell seems to visit us for a few days/weeks then goes away for weeks to months. We passed most of the fall and into winter without noticing it, until the health department did their yearly inspection on our septic system. Since then (about 4-6 weeks) we've had to run the exhaust fan 24/7.

    I was going to replace the wax seal on the toilet, but the toilet is grouted to the tile floor. Not wanting to break out that grout, I have left it in place.

    Two plumbers have looked at the problem and scratched their heads.

    Any thoughts on what to check?

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  2. heat seeker

    heat seeker Minister of Fire

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    That would be my first guess for leakage. Re-grouting isn't all that hard to do. If you're sure the sink drain pipes are not leaking (maybe even in the wall), there's not too much left. Too bad there's not a way to get a smoke bomb in the drain to see where the smoke comes out!
  3. Hogwildz

    Hogwildz Minister of Fire

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    Make sure the traps aren't rotting through if they are chromed steel. I had that happen to a sink trap in my old place. Was feeling around the trap and put my thumb through the thing. The chrome was all that was left in one spot. The other thing I found, was the drain pipe from the trap to the concrete pad was not air tight. There was drain pipe in the pad barely sticking out at all, and the drain pipe from the trapt to the pad pipe was merely notched and pushed down into the pc of pipe in the pad. I was able to solder it, and that helped with a smell we had in the bathroom.
    Does your toilet rock? or is it solid and secure. Mine had a bad seal due to the cast iron pipe flange at the base mount sticking up too far, and the new toilet was shallower on the bottom then the original toilet. The new one actually was rocking on the top of the cast iron pipe end. I ended up taking a hammer and breaking of small pcs of the cast iron pipe enough to chip it down to the ring flange. Scary stuff, was worried about cracking the cast iron, and that was also set in the concrete pad.
    I also ended up installing engineered flooring in that bathroom also helped shim the new toilet up enough to clear the pipe & ring flange, and stop it from rocking. 2 wax rings (doubled up)never did work for the first try at fixing that issue.
  4. maverick06

    maverick06 Minister of Fire

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    I had a similar problem. I first thought it was the trap in the sink dried out, running the sink once a month would fix this. Long story short, i am almost certain it was a mouse that died in the wall... nasty smell for a few weeks then nothing. i have had mice and couldnt find anything wrong with the bathroom.
  5. Ehouse

    Ehouse Minister of Fire

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    Is there a vent stack for this set up? If it's not vented, sewer gas can rise up to the traps and may come by them when the fixture is operated. A strong flush from the toilet can pull the water out of the sink or shower trap. You can remedy this with an air admittance valve.
    pen, ScotO and Lighting Up like this.
  6. Lighting Up

    Lighting Up Feeling the Heat

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    I'm with Ehouse...vent pipe...depending how old the bathroom is they never put them in.;sick Just my guess...
    ScotO likes this.
  7. legrandice

    legrandice Burning Hunk

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    I agree, my first guess would be a venting problem. You could have a blocked vent stack. My inlaws had a blockage due to some snow and a dead animal...made the house smell pretty bad.
  8. Hogwildz

    Hogwildz Minister of Fire

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    I have a run that the previous owner did not run a vent stack. Whenever we use either the sink or the washer, the other will gurgle. Both have admittance valves in them, but the problem is they only let air in, not out. And my situation is back pressure pushing out. Luckily, that vent set up goes outside and daylights out the side of a hill. It is not connected with the main sewage line to the septic tank, so no bad fumes or gases, but annoying gurgling.. At some point I am going to try and change this problem line from 2" to 3" as far as I can before it runs in the basement through the basement wall, and add a vent stack somewhere if possible.
  9. Defiant

    Defiant Vermont Castings Geek

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    Great advice from all, traps and vents:cool:
    ScotO likes this.
  10. Ehouse

    Ehouse Minister of Fire

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    You need to have an open vent to daylight (roof or side wall) to use AAV's because as Hogwildz says, they only solve 1/2 of the problem (let air in). Without a main stack venting out, sewer gas will find a way up and out (gurgle) when you turn on the tap or flush.
  11. Corey

    Corey Minister of Fire

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    Some friends of mine worked in a building - same story...every few weeks they would smell sewer gas in the bathroom area. Filled the traps, flushed clorox, detergent, used air fresheners, replaced seals, wax gaskets,etc. The smell remained. Finally, they started tearing into the bathroom determined to fix the smell one way or the other. Found the vent pipes all properly routed to the main vent stack, main vent stack went up through the ceiling as expected ... then it terminated in the space above the suspended ceiling but below the 'true' ceiling... without going through the roof.

    The toilet sounds like a good possibility for a leak, but if you don't find anything there, you might have to look at more unlikely possibilities. I think there is a method of 'fogging' the vent pipes so you can look and see if any smoke/fog is coming from unexpected places. So that might be an option if you can't locate any other leaks.
  12. billb3

    billb3 Minister of Fire

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    I've seen cast iron horizontal pipes rot and crack along the top.
    You could actually watch //stuff// go by after a flush.
  13. Swedishchef

    Swedishchef Minister of Fire

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    I had a fairly poor smell in my bathroom. In the end, my wife was losing lots of hair (post pregnancy thing) and I found a decent size hairball stuck in the shower drain with pieces of soap,, etc. it had left a gross smelling film on the inside of the drain. Some draino foam x2 and the problem was solved.

    However like everyone here said, check traps and vents too
    ScotO likes this.
  14. ScotO

    ScotO Guest

    Great advice from all here. First thing is to check for proper venting to the outside of the house. One other thing, make sure EACH AND EVERY drain connection has its OWN trap. I've see installs before where the chitter had a trap, but the sink and shower DID NOT. Amateur mistake that a DIY plumber must've made......that smell plagued the room for years and years......
    Also, make sure your horizontal drainpipes have the proper slope, and have adequate suspension or strapping to prevent the pipe from sagging over the years. Schedule 40 PVC will sag and create low spots if there's not enough support on the long horizontal runs, and that can lead to "stuff" laying in those pipes.....
    Keep us posted, I hope you find the problem.
    vinny11950 likes this.
  15. Hogwildz

    Hogwildz Minister of Fire

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    All toilets have their own trap built in, so that won't be an issue. But Scotty is right, there are many numbnuts out there that just do things without proper knowledge of how to do these things.
    Speaking of stink..... I was in the shower last night, and when I got out to dry off, a "stink" filled the bathroom after a strange bubble exited my posterior. . BAHAHAHAHAHA
    vinny11950 and ScotO like this.
  16. heat seeker

    heat seeker Minister of Fire

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    The toilets do indeed have a trap built in, but if the wax ring leaks, odor will get into the room. The trap is above the wax ring.
    ScotO likes this.
  17. TresK3

    TresK3 Member

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    Thanks to everyone for the great advice/thoughts.

    The toilet is rock solid on the floor and I don't see any cracks, etc around the grouting, so I'm not visualizing gas getting out that way. The shower also has a trap, and you can see water in the trap if you remove the drain cover, so that looks pretty good. I'll check the sink trap very carefully - that sounds like a possible culprit.

    I'm pretty sure that the set up has a vent stack (unless the pipe I'm looking at is a sewer pipe from upstairs), but I'm a little worried about where it goes. This bathroom is next to the 3-flue chimney that exhausts both fireplaces and the oil furnace. What if they ran the vent into one of the chimney flues? If it went into the flue for the fireplace where we installed our insert, then the SS liner could be blocking the path out.

    What would happen if I disconnected the sink trap, shoved a (lit) smoke bomb into the pipe (maybe attached to a piece of wire, so I could pull it out, later) and quickly sealed the open end. Then I could go outside and see where the smoke was exiting. Bad idea? Good idea? Waste of time?

    In the meantime, I think we'll stop using the bathroom for awhile just in case the gasses are coming up when we run water.

    Thanks again!
  18. G-rott

    G-rott Member

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    How large is the vent going through the roof? I have had them close up with frost during cold weather if they are undersized, then they thaw out in warmer or sunny weather.

    Is there any gurgling of the drains when water is used elsewhere in the house?
  19. lukem

    lukem Minister of Fire

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    Could be a frozen vent, could be no/improper size vent.

    I've seen where a toilet flush with improper venting will create enough vacuum to suck the water out of a trap. If you stick your nose close to the sink or shower drain do you get a good whiff of it? If so, and you'll know for sure by the smell, you have a trap issue. If not, you've got something else going on. Not sure what though...but I'd first try to rule in or out the trap issue.

    EDIT: long-shot, but do you have propane or nat gas in the vicinity that could be leaking? That has a certain funk to it that could be mistaken for sewer gas.
  20. TresK3

    TresK3 Member

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    Thanks for the thoughts.

    No gas in the area... at least not the fuel kind. The smell does seem worse in certain seasons, but we've had enough warm spells that I don't think actual icing is a problem. No significant gurgling from pipes in the basement bath. Sometimes on the second floor we get some gurgle from the sinks, when the toilet gets flushed, but there doesn't seem to be much of a smell issue up there. Mostly it's in the basement.

    I checked the trap around the sink, and that seems to be in pretty good shape. Last year, when we had this issue, I sealed off the shower drain for a few days, without much success.
  21. G-rott

    G-rott Member

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    The gurgle is a sign of no vent or a blocked vent, good venting equalizes pressure = no gurgle. You could add an air admittance valve under the sink in each bath, its a one way pressure balance air valve.

    Some times we just end up with too much negative pressure in a house and the vent stack ends up being the path of least resistance for make up air.

    Furnace vents and vent fans, natural and man made draft (wood stove), and the opening and closing of doors and windows all make a difference in the air pressure in the house.
  22. woodsman23

    woodsman23 Minister of Fire

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    double the wax ring and be done with it.
  23. firefighterjake

    firefighterjake Minister of Fire

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    Are there any showers or sinks that are rarely used . . . at work the water in the shower trap in my office bathroom (which never gets used) occasionally dries up allowing some sewer gas to escape into the bathroom.

    I also assume that you or the plumbers have checked the entire system for any blockages and a working septic system.
  24. rwhite

    rwhite Minister of Fire

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    In addition to the other suggestions ....are you sure it's not sulfur smell? We have a bit of sulfur in our water and the gas seems to collect in the basement pipes. Comes out when I run the water in the basement only, never get the smell upstairs. Best way to get rid of it is keep the the hot water heater at about 140 and drain it every 6 months. This was suggested to me by a plumber and I have not had an issue since. I have no idea why but it doesn't smell in the cold water, only when we had the tank at around 120 would it come out the hot water.
  25. vinny11950

    vinny11950 Minister of Fire

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    just to throw something else out there, make sure it is not some sort of animal doing his/her business nearby. that was the case at my parents house in the basement. come to figure out after months of searching that the neighborhood cats have a pissing contest on a certain section of outside wall which has wood siding that absorbs some of it and off gases. this cause my moms cat to retaliate from the inside and pee in one corner which dripped into the basement. a mess. the randomness of your situation might point to a situation like this.

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