Methane Odor in Basement Bathroom

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by artistsnature, Oct 22, 2008.

  1. artistsnature

    artistsnature New Member

    Messages:
    14
    I'm a single mom in Jersey and I try to do all my own work. The house I bought a year ago had A LOT of plumbing "issues". The septic failed, the well was filled with bacteria, the well tank inside was filled with silt, mud came out the faucets. All that was "fixed" before I moved in. Originally I thought the smell in the basement was due to a propane leak - which was true, and I replaced both the propane fitting on the dryer and the propane oven above. That helped, but the smell continued. I tore down the moldy ceiling in the basement bathroom to fix a loose, dripping fitting in the trap of the shower above. I replaced the sink and toilet in the basement bathroom. I installed a trap missing from the stand pipe of the washer. The downstairs shower isn't functional - when I started to refinish it, I saw that the handles are six inches off center, and I haven't tackled that yet. So I periodically pour water down the shower drain to make sure the trap - if it exists, which I doubt because the whole bathroom was just slapped together - stays wet. I even installed a bathroom vent, but it's no match for the smell, which gets much worse when I run the dishwasher or shower.

    I thought the problem was the vent stack - it's a steep pitched A-frame roof, and the stack is below the top bathroom, and only sticks up 6 inches. There's only one 1.5" stack in the entire 3 bathroom house, which seems inadequate. It looks like the upstairs 1/2 bath is unvented (that sink is also not working, because it's rotted through and I just shut off the supply). The methane odor used to consume the back yard, but I extended the stack two feet and that helped outside.

    The gutters of this house hadn't been cleaned or maintained in decades, which caused leaking in the basement. I fixed all that. But I wonder whether the vent stack, which was not capped, could be clogged too? The leaves were so composted in the gutters that they turned into the richest soil I've ever seen - could that be in the stack too? I don't have any drainage problems in the appliances, so I doubt that the vent stack is clogged, and I also don't hear any gurgling.

    When I started to re-do the basement shower, I did not replace the pan - even though the septic had backed up in there decades ago and the shower was full of crap. Should I pry off the pan to see if there's a trap? Should I run a hose down the vent stack to see if it's clogged? Should I do a peppermint oil test? Do I need to install an extra vent stack? I really don't know what I'm doing, although I muddle through and figure a lot out. But I can't afford a plumber - can you help?

    THANKS!
    Caryn
    Last edited: Oct 22, 2008
  2. xroad

    xroad New Member

    Messages:
    113
    I tend to like to rip out old plumbings and replace with new, Get cheap stuff if necessary but it has to be new. Old stuff just not worth the time to struggle with.

    If you don't have the time to rip into the pan to see if there is a trap, just seal it and wait for a few days to see if the smell discipates. Once you rip it out, you are in for that project until it is done. I am sure you have other more pressing jobs. Find a cap, an old pie pan or something to cover the drain with a bead of caulking for seal.

    Looks like you have some major issues. Take care of the health risk issues first. Stabilize situation and decide what to tackle first. If the basement is always wet, from the septic tank? That is dangerous to your family's health.

    Good luck.
  3. khayes

    khayes New Member

    Messages:
    53
    Location:
    Alpharetta, GA.
    We had a similar problem in a house years back - would get the odor in the basement after it rained or after a large amount of water usage, ie. running the clothes washer (which was also in the basement). It turned out to be a section of crushed field line going to my septic tank. Once I had that replaced, the problem went away. Good luck.
    Last edited: Oct 23, 2008
  4. artistsnature

    artistsnature New Member

    Messages:
    14
    Basement Odor/ Vent Stack

    Interesting thought - although the entire septic system was replaced, from the output pipe to the tank to the field, so unless the problem is under the basement shower, I assume the lines are ok.

    Does anyone think that I need to install an additional vent stack? Is this a job a novice can take on? The top-most bathroom is covered ship to stern in tongue and grove knotty pine, so I'd hate to have to rip it out. But if venting that bathroom would make the odor in the basement bathroom go away, I'll do it. I just hate to start that project if it doesn't fix the problem. (BTW, I had a plumber out and he said it would not fix the problem. He said it was the missing stand pipe trap, which I installed, and the odor did not change).
  5. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio
    go buy a rubber stopper/cover and place it over the shower drain and see if it changes anything
  6. artistsnature

    artistsnature New Member

    Messages:
    14
    Rubber stopper

    Yeah, already tried that. No improvement.
  7. patrick88

    patrick88 Plumber

    Messages:
    836
    Location:
    Webster Ma.
    I would try a smoke test. The peppermint test can be a real pain. The peppermint gets in your nose and you smell it every place.
    You could have a cracked pipe some place under the shower. I would not bother lifting the pan until you know you really need to.
  8. Southern Man

    Southern Man DIY Hillbilly

    Messages:
    530
    Location:
    North Carolina
    Before you do anything call your propane supplier and have him test all the gas lines for leaks. He'll probably do it for free. Once you get that eliminated as the problem then you can do a smoke test for the septic system. Call up a local tank cleaner and have your tank pumped and cleaned, and the house sewer smoke tested.
  9. artistsnature

    artistsnature New Member

    Messages:
    14
    I have been considering a smoke test, although I've read that they can be screwed up (not enough pressure, etc.). Is this something I can try myself - rent a machine somewhere - or do I need to leave this one to the pros?

    BTW, the septic was new less than a year ago - it had evidently not been pumped for a very long time, because not only had it backed up into the downstairs shower, but during the test they found the soil around the tank (overflowing) completely saturated for six feet down. Between the septic backup and the silt from the well, I'm wondering whether there could be a clog somewhere......
  10. Southern Man

    Southern Man DIY Hillbilly

    Messages:
    530
    Location:
    North Carolina
    I've never seen the smoke tablets on sale at any DIY place. That test is done by placing the tablets in a low spot in the system and having the smoke rise up through the house drains. It should all exit the roof vents and if not you'll know where leaks are. Unless you know at least the rudiments of this and how the plumbing is laid out you should leave this to the pros. And this is coming from someone who is loathe to call in a pro.

    Assuming that you don't have a propane link (see my last response, please) and your septic system is OK that the problem is likely to be all the spilled sewage in the yard.

    Is your septic system operating properly? If the system was never pumped out for a long time then it backed up by clogging the drain field below the tank. That's a very common occurrence for systems that aren't maintained and once it occurs then the drain field has to be replaced. Was this done? If not then the system will back up again and that's were your odor is coming from.

    The other possibility is due to septic spillage in the soil around the tank as you described. If it's close to the house then it may have saturated the building footing drain and then in the gravel layer below the floor slab. In older homes the basement sump is part of this system. If this is the case then you'll have to isolate the sump. You might be able to vent the slab and/or walls using a fan driven system similar to what is used for radon removal.
  11. artistsnature

    artistsnature New Member

    Messages:
    14
    I do have propane tanks, but they were replaced 6 months ago, when the propane leaks were fixed. Only the dryer and oven are on propane. Is it safe to do a smoke test with propane in the house?

    The septic system is brand new - tank, field and all. When they were replaced, so was all the soil, so there's no odor in the yard itself. That's why I can't figure out where the smell is coming from in the basement bathroom. Is it worth it to get a gas detector at a DIY place? Of course, the septic guy says call a plumber, and the plumber says call the septic guy!

    So if the smoke test starts at the lowest point, the tablet would be put in the shower drain? And isn't there a machine that blows the smoke through the system?

    Thanks for all your help!
  12. Southern Man

    Southern Man DIY Hillbilly

    Messages:
    530
    Location:
    North Carolina
    Is there water in all your traps? Do you have a floor drain that is never used and the water evaporated out? Do you have a sump that collects from the footing and is that where the odor is coming from? Check all the obvious before you worry about smoke testing.

    I've only done smoke tests on public sewers. We seal off one pipe in a manhole with a rubber plug and hang a smoke candle in the manhole, and use an explosion proof fan set on the back of a truck and connected to the manhole with a 2' diameter expandable hose (like a huge dryer hose) to put it under a slight pressure and force smoke up the other pipe. We then look at the connected homes to make sure all the smoke is going out the roof vents, and check with the occupants that there's no smoke in the homes.

    I suppose with an individual house on septic you would open an access hatch on the tank and do the same thing. But the problem is that there is water in the tank within 2-4" of the top. You'd have to figure a way to plug the effluent end during the test, and making sure that the inlet end is not underwater. Then you have to have a fan small enough but powerful enough to put a slight pressure on the tank, and for it not to spark the combustible gas that is likely to be in the tank. Boom!

    Maybe you could rent an explosion proof fan and the expandable hose, but that's going to be huge and expensive. Otherwise the only fan that I think would be safe enough would be an inline fan that connects to a 4" line like one used for radon remediation. Those can be bought for about $100. You can get a long length of dryer hose, like 20', and set the fan safely away from the tank and make sure its blowing the right way (towards the tank).

    By the time you do all this you'd have spent about two days and $200 or more, so it's probably cheaper to call a pro who already has the equipment.
  13. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Maybe just call a pro?:cool:
  14. Southern Man

    Southern Man DIY Hillbilly

    Messages:
    530
    Location:
    North Carolina
  15. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Somehow tossing M-80's into the septic tank doesn't seem like the way to go... I usually plug the septic tank during a smoke test and I also do not bring the generator inside the house.
    Just a few thoughts on the subject that may make it worth the money.
  16. artistsnature

    artistsnature New Member

    Messages:
    14
    Is there water in all your traps? Do you have a floor drain that is never used and the water evaporated out? Do you have a sump that collects from the footing and is that where the odor is coming from? Check all the obvious before you worry about smoke testing.

    Ok you guys, now that you've put the fear of God into me about smoke tests, I'm just about ready to take out a second mortgage and call a pro! I do have a floor drain issue, which I don't think is related, but you be the judge:

    There is no sump pump and the traps are all wet. There is a floor drain in the utility room on the other side of the basement from the bathroom, and there is no smell from it. Not only was it dry, but when I pried off the top and shown a light, it appears that there's a hole in the bottom of it, which then leads to another gravel pit a few feet below. This drain is right below the well tank outlet, but really does not get used, as far as I can tell. Could this effect the smell in the basement bathroom?

    Here's another question: if the drains are all working, wouldn't that indicate that the vent stack, however small, is working? In that case, wouldn't a smoke test be useless?

    So if it's not the vent stack and it's not the traps, WHY THE HECK DOES MY BATHROOM STINK?????
  17. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    My guess that more than likely its funk growing in the shower pan.
    If the other common sources have been checked... Dry traps and leaking wax rings then proceed to the smoke test... It will uncover the dwv system leak if there is one. The smoke will give a visable indicator of any leak present.
  18. artistsnature

    artistsnature New Member

    Messages:
    14
    But if it's funk growing in the shower pan, why does it only stink when I run the dishwasher or the upstairs shower?
  19. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Hmmm Smoke Test!
  20. Cass

    Cass Plumber

    Messages:
    5,980
    Location:
    Ohio

    When you run water there is air movement through your DWV system and it is finding its way out somewhere where you can smell it instead of through the roof vents. This is why a smoke test may find the problem.

    I had a friend who had a similar problem and we smoke tested and never found anything.

    His odor would come and go different times of the year mainly spring and fall.
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