Strange smell coming from basement bathroom

2 years ago

last modified: 2 years ago

Starting just a few weeks ago, I've noticed a foul smell coming from the basement bathroom. More noticeably, the smell is non existent in the morning when I go to the basement for work, but once I flush the toilet the smell starts to appear. The best way I can describe the smell is that it smells like someone is smoking weed. For some background, last year we remodeled the bathroom in question, and for a while our toilet and sink were completely disconnected and I can remember noticing a similar smell during that time. We did have to put a new wax seal on the toilet when we reinstalled it, but to my knowledge we did that correctly, the toilet does not rock when you sit on it. I did some troubleshooting with the sink and ran some vinegar and baking soda through it to clean out the p-trap, but the smell is still there which makes me think it's coming from the toilet. Any ideas as to what this could be?

Comments (10)

cat_ky
2 years ago
last modified: 2 years ago
Is your toilet and sink, etc in there vented out through the roof? If so, is the vent disconnected somewhere. This sounds very much like the smell, from an unvented plumbing, of which toilet would be the worst. If you find that it is vented, and isnt disconnected somewhere, then climb up on your roof, and check out that vent pipe. Birds have been known to make a nest over the vent opening. You can also run a snake down that vent from the exterior, just to make sure. Sewer gas is not healthy to breathe, so its something you need to do asap.
Will Walker
Original Author
2 years ago
I live in a townhome and we recently had our roof redone, so possibly something was done that is blocking the vent? I'm honestly not sure of the bathroom is vented through the roof but if it is, wouldn't this affect the other bathrooms as well?
Related Discussions
Terrible smell from bathroom drain...
Q
Comments (7)
I have the same problem with my upstairs bath, which comes and goes (the smell problem, not the bath :). I noticed a sewery smell comes out of there during the first few minutes of running water. I was envisioning some gas bubble that gets dislodged when water goes through the trap. I finally asked a plumber about this. He said that the smell is, indeed, caused by "gunk". Namely, the gunk that collects inside the sink itself - i.e. the space between the slot that prevents the sink from overflowing and where it joins the pipe just below the drain opening. It's almost impossible to clean in there, but he said you could try to use bleach and pipe cleaners. The gas bubble idea still makes more sense to me, but I guess he's seen his share of gunked-up sinks.
...See More
Sewer gas smell in the basement bathroom
Q
Comments (5)
We also just had one bathroom with a "sewer smell". In our case, when the water was first turned on in the sink, there would be a blast of the foul odor. First I thought it was the water itself, but then I decided to catch the water in a pot - no smell then. But when I poured it down the drain, up came the smell. Aha, perhap ssome bacteria, etc down the drain. So I poured a bit of bleach down the drain and that took care of it. Hope this helps solve your problem. (BTW, if that wasn't the cause, my next step was to pour some bleach down the sink & tub overflow drains.)
...See More
smell from bathroom sink drain.
Q
Comments (3)
When you catch a whiff, I'd take the trap apart and see if there is any water in it. I suspect the trap is dry and you are smelling sewer gas. Realistically, unless your directional sense of smell isn't very good, it really can't be anything else. If the trap is dry, your vent is probably plugged and another fixture is siphoning the trap. IMHO
...See More
Foul smell emitting from bathroom sink & other odd sink behavior
Q
Comments (2)
I had a smelly bathroom sink once. It would smell for a few seconds after I started running water, then dissipate. I suspected trapped gas in the pipes or something. When I had a plumber over for an unrelated problem he said that the smell might come from the space between the overflow opening and the drain. Stuff gets caught in there over time and is just about impossible to clean. When you turn on the water, the gas that sat in that space gets forced out of the overflow hole. Something like that. I dribbled some disinfectant cleaner into the hole and a bottle cleaner to wipe around a bit, then rinsed. That seemed to have helped.
...See More
worthy
2 years ago
last modified: 2 years ago
Not all bathrooms share the same roof vent.

I called two drain companies to check a similar problem. Both refused to climb to the second storey, even though the vent was accessible without leaving the ladder. You may encounter similar scaredy-cat plumbers as well.
cat_ky
2 years ago
last modified: 2 years ago
Like worthy said. Each bathroom, and kitchen and laundry room, should have their own vents. Venting is a requirement for all systems, so that sewer gas doesnt kill you. Venting into a crawl space, or basement, or attic is a huge no no, because sewer gas is still getting into your dwelling. It must go to the exterior of your house, and be up high.
Izzy Mn
2 years ago
last modified: 2 years ago
It may be your vent, or could be your sink drain.

I found out my problem/cure from googling problem. We had recently replaced the sink stopper and faucet in bathroom. Shortly afterwards noticed sewer smell occasionally, few times a day. Yes, sewer smell is a skunky smell most times. My googling efforts said to check the overflow of the bathroom sink to see if clogged.

I checked by using a funnel and pouring water into it to see if water drains. Sure enough it was clogged. When installing drain stopper we got excess plumbers putty into the hole that drains into the pipe. We are amateurs at home improvement and something usually goes wrong/not smoothly. After some fiddling with something to clean out putty and water drained properly no longer had sewer gas. It was explained on the Google info the clogged overflow sometimes causes some weird suction when toilet is flushed causing sewer gas to come up...

Good luck.
Will Walker
Original Author
2 years ago
Wanted to provide an update to everyone. I had a plumber come out yesterday. Of course I was unable to recreate the smell when they were here, however they hung around for a while as we flushed the toilet and still no smell. They didn't see anything wrong with the toilet or sink plumbing or any signs of leakage or water damage anywhere. They were pretty sure it wasn't a venting issue since I live in a townhome and I would have noticed the signs in other bathrooms.

One thing I forgot to mention in the first post was that the bathroom in question has a shower that never gets used. The plumber almost immediately asked me if the shower ever gets used, and when I said no, he identified the smell could be coming from the shower p-trap water having been evaporated. Long story short we ran a bunch of water through the shower and I can say that I have not smelled the problem since. So I'm thinking it was the shower p-trap.
cat_ky
2 years ago
Happy to hear you had a plumber, and hopefully, all it was, was an unused shower. Maybe try to use that shower every now and then, or at least pour some water into it, every other day or so.
Will Walker
Original Author
2 years ago
Yep definitely going to run water through it once a month now.
Nancy R z5 Chicagoland
2 years ago
Funny, I was going to suggest checking the shower before I read all the way through your story. Every so often, I have to pour some water down the drain in my basement shower to prevent it from drying up. When it gets dry, the sewer gas can escape from there somewhere. This is a very common problem but an easy solution.
cat_ky
2 years ago
You need to run water in it more often than once a month. At least once a week, would be so much better.