Occasional Musty Odor In Bathroom

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artistg90

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Hi Everyone,

I recently purchased a new house and over the past few months have noticed an occasional musty odor in the bathroom. The odor is not always present but seems to be more pungent after showering or heavy rain. The house is a traditional cape with a shared wet wall. I have inspected all of the plumbing connections in the basement and in the attic crawl space which all look to be in good condition. The house is a mix of cast iron and PVC. I also do not notice the order in any other room in the house. There are no signs of water damage on any of the walls or floors.

I am beginning to think I am smelling sewer gas from some pipe that is leaking. The two areas I suspect it is coming from is the toilet and shower drain. The toilet is not installed level with the floor and has a 1/4" bead of caulk around the edge. If the wax ring was not installed correctly would I be smelling occasional sewer gas even though there is a p-trap? The other area I noticed something was wrong with was the shower. When the tub is drained it makes a very loud gurgling sound like it is chocking on the water. Not sure if this would have anything to do with the smell.

Does anyone have any other recommendations where the smell could be coming from? I am trying to figure out why the smell is more pungent after heavy rain/showering. Is there anything I can do prior to installing a new toilet that could solve the problem?

Thanks for all your help.
 
Hi Everyone,

I recently purchased a new house and over the past few months have noticed an occasional musty odor in the bathroom. The odor is not always present but seems to be more pungent after showering or heavy rain. The house is a traditional cape with a shared wet wall. I have inspected all of the plumbing connections in the basement and in the attic crawl space which all look to be in good condition. The house is a mix of cast iron and PVC. I also do not notice the order in any other room in the house. There are no signs of water damage on any of the walls or floors.

I am beginning to think I am smelling sewer gas from some pipe that is leaking. The two areas I suspect it is coming from is the toilet and shower drain. The toilet is not installed level with the floor and has a 1/4" bead of caulk around the edge. If the wax ring was not installed correctly would I be smelling occasional sewer gas even though there is a p-trap? The other area I noticed something was wrong with was the shower. When the tub is drained it makes a very loud gurgling sound like it is chocking on the water. Not sure if this would have anything to do with the smell.

Does anyone have any other recommendations where the smell could be coming from? I am trying to figure out why the smell is more pungent after heavy rain/showering. Is there anything I can do prior to installing a new toilet that could solve the problem?

Thanks for all your help.
Can you see the trap and drain line from the shower in the basement? It sounds like it may not be vented properly or possibly wet vented with a drain line that's should be larger and/or has too steep of a slope.

Also, toilets typically have an integral trap and do not have a p-trap.
 
Hi Everyone,

"When the tub is drained it makes a very loud gurgling sound like it is chocking on the water. Not sure if this would have anything to do with the smell. "


Do you hear that gurgling sound after it is drained or while it is draining? If after it is draining then it almost sounds like it might have an unvented trap and it's basically siphoning the water right out of the trap and that would cause the sewer gases to come back through.
 
It is possible for wax ring to allow air thru but no water. I can take a long bbq lighter and run around base seam. Turn the fart fan on. If your flame twitches then you have a draft and should fix the toilet to it setting correct. This might mean new sobfloor. But a toilet without a level flat foundation will always leak. Shins work but after awhile wax still breaks.
 
@Diehard - I can see the trap and drain in the basement. The shower is vented with a 1 1/2" existing steel pipe that ties into the main stack vent in the crawl space above the bathroom. I can take some pictures tonight. The trap is about 18" below the tub. Not sure if that would cause the gurgling noise. Maybe there is enough force that it is pushing the water out of the trap?

@mdk0420 - I only hear the gurgling sounds while it is draining.

@Jamesplumbing06 - I will try this out tonight. What blows my mind is the floor is perfectly level, but for some reason, the toilet is about 1/4" off.
 
@Diehard - I can see the trap and drain in the basement. The shower is vented with a 1 1/2" existing steel pipe that ties into the main stack vent in the crawl space above the bathroom. I can take some pictures tonight. The trap is about 18" below the tub. Not sure if that would cause the gurgling noise. Maybe there is enough force that it is pushing the water out of the trap?
Take note of the distance between the trap and the vent pipe connection. Also if it looks like the slope of the drain line between the trap and the vent exceeds 1/4" per foot by much. A simple 2 foot level of course would show a 1/2" space when held level on the pipe, if 1/4" per foot.
 
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