Help identify a musty smell in a bathroom?
October 29, 2013 8:32 AM   Subscribe

Our small main floor 2-piece bathroom has had a musty smell for the last couple of months. We can't seem to identify the source and aside from the smell there is no sign that anything is wrong. We had a plumber in and he spotted a very small amount of (orangy coloured) mould inside the toilet tank, but even after cleaning that up with MoldEx the smell has not abated. What could it be?

Other pertinent information:

The smell comes and goes. At some points it is quite strong, and at others it is barely present at all. I haven't been able to identify any correlation between our activities and the smell, though I think that the smell is reduced when the toilet is flushed more frequently.

There is no sign of water anywhere. There's a finished basement below and there is nothing on the ceiling there, nor is there any sign of water around the toilet. The plumber confirmed this.

The smell is confined to the bathroom. You can't smell it outside the bathroom at all, on any side (two sides are accessible, including the wall that the toilet is on), or below. The sink does not smell, nor is there any sign of mould anywhere near it.

The bathroom does not have any windows and does not get much, if any, natural light. It may have been under-used for a couple of months before we moved in the spring; the people we bought from had already moved into their new place but were, we think, using this house occasionally for laundry and moving things out slowly.

I'm not sure if there is any other information that would be useful. We do live in a somewhat humid climate. The toilet has been used regularly since we moved in in early April, but the smell didn't really hit us until maybe August or September.
posted by synecdoche to Home & Garden (15 answers total) 4 users marked this as a favorite
You may have a dead mouse or other rodent in the walls.
posted by jen14221 at 8:33 AM on October 29, 2013

Some type of mold or nastiness in the flange / wax ring area? can you change out those parts and see if it makes a difference?
posted by WeekendJen at 8:42 AM on October 29, 2013 [1 favorite]

no window, but is there maybe a ventilation fan? if it vents to outside, check whether it's near trash or other damp yuckiness...
posted by acm at 8:44 AM on October 29, 2013

Something in the water, maybe?
posted by jquinby at 8:45 AM on October 29, 2013

Could be a drain emitting odor, or a small leak behind the wall. Is the smell stronger in the cabinet under the sink? That's a prime area for leaks and stuff.
posted by Ruthless Bunny at 8:50 AM on October 29, 2013

Check the vent stack for partial obstruction. And/or sometimes the stack can emit odors from another location.

Agree with removing the toilet and checking for a slow leak at the wax ring since it may not be obvious to visual inspection.
posted by mightshould at 8:59 AM on October 29, 2013

We do live in a somewhat humid climate. The toilet has been used regularly since we moved in in early April, but the smell didn't really hit us until maybe August or September.

This is what jumped out at me. I was having a similar "I smell mildew but can't find it" problem in my kitchen once, in the cabinet under the kitchen sink. My super suggested getting a Damp Rid container and leaving it under there; that took care of the smell within, like, a week. I put a fresh one in there every year, and it hasn't come back.

Those Damprid things are pretty easy to find and fairly inexpensive, too. They also make ones just for bathrooms (you hook it on the tank).
posted by EmpressCallipygos at 9:02 AM on October 29, 2013 [1 favorite]

Oh, forgot to mention - the reason my super suggested it was more from a principle of "well, if it is mildew, this would eliminate the humidity which would cause mildew".
posted by EmpressCallipygos at 9:03 AM on October 29, 2013

I'm betting it's coming from the sink and/or tub drains. Dump a bit of some sort of disinfecting cleanser down the drain, then let it sit a few hours or overnight. Even vinegar will work (followed by baking soda for bubbly fun). I need to do this every few weeks.
posted by Corvid at 10:31 AM on October 29, 2013

Towels or bathmats?
posted by fshgrl at 11:26 AM on October 29, 2013

This is a real long shot, but do you happen to have a front loading washer nearby? We tried for months to locate the musty smell in our bathroom, never realizing that the clothes washer was full of mold.
posted by MelissaSimon at 11:34 AM on October 29, 2013

I never had an odor problem with real Westinghouse Laundromats, but the front loader I have now does smell slightly. I leave the door ajar when it is not in use to reduce mustiness. I have seen ads for washing machine cleaner substances; these were not previously necessary, but I do not know what has changed.
posted by Cranberry at 12:01 PM on October 29, 2013

I'd get a dehumidifier. If we don't run ours constantly our bathroom gets kinda funky smelling in a couple of days.
posted by PuppetMcSockerson at 12:25 PM on October 29, 2013

Response by poster: Thanks everyone. I think it is the toilet, not the sink. They are on opposite walls and the odour is definitely stronger at the toilet end of things. There is no tub, just the toilet and the sink. It's definitely not the towels. We do have a front-loader but it is up stairs and down the hall. Water smells fine everywhere else.

I'll try the Damp Rid first and see if it helps before moving on to more drastic solutions, I guess.
posted by synecdoche at 1:34 PM on October 29, 2013

Second the wax ring/flange where the toilet meets the drain pipe at the floor. I had a long standing leak that was not discovered until we pulled up the vinyl flooring. The repair was relatively inexpensive.
posted by zoel at 6:18 PM on October 29, 2013 [2 favorites]

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