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Mike R.
Mike R., Plumber
Category: Plumbing
Satisfied Customers: 1416
Experience:  20 years of plumbing experience, including high end homes and service work.
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We are having a problem with an intermittent smell in the bathroom.

Customer Question

We are having a problem with an intermittent smell in the bathroom. It's a stale urine smell that appears after a hot shower, but not every time. It seems to happen most often after shower combined with subsequent use of the bathroom sink. We got no observable clogs in bathtub or bathroom sink. I cannot tell for sure which drain is the source - sometime it seems to come from bath tub, some times from the sink. Any suggestions what it could be?
Submitted: 2 years ago.
Category: Plumbing
Expert:  Plmqwk replied 2 years ago.

Welcome to Just Answer. I will do my best to fully answer your question(s).

Identifying intermitant plumbing odors are one of the most difficult problems to diagnose. However some things to do to reduce some of the possible sources are, install new wax ring on the toilet/ drain connection and clean the flooring around the toilet with mild bleach solution. Also pour the bleach solution into the overflow areas of the tub and lavatory sink to remove mold buildup in these moist areas. If the smell still occurs then its time to hire a professional to use an odor (gas) dectector to attempt to locate a possible pipe/ vent leak for sewer gas. Look for any drains that are rarely used and put water down them to eliminate traps that have evaporated from lack of use.

Customer: replied 2 years ago.
Is it possible to narrow it down? It's always the same type of smell - "stale urine", never the "rotten egg" sulfuric smell, never moldy. When it happens, it's always after prolonged hot shower. While not 100% sure, but I think it happens once the use of hot shower is followed by use of cold water in the sink or the tub. The toilet area is cleaned regularly, with bleach, like you said. House is less than 10 years old. No unused sinks/drains.
Expert:  Plmqwk replied 2 years ago.
This gets really tough without being there and able to smell it myself. i dont expect you to pay me tonite. i cannot think of anything else at this point. The hot water may be the source. another thing to eliminate that possibility would be to drain the heater completely and refill. See if that changes anything. I did mention replacing the wax ring on the toilet. Just one more thing to eliminate as a source, but I doubt that it is the source myself. I'll opt out and see if another expert has more to add.
Expert:  Mike R. replied 2 years ago.
could be mold under the tile. if you have a tile shower the water will get under the tile and if the weep holes that are in the drain are clogged then the water will sit. does the smell resemble fuel at all like natural gas? also could be the anode rod in the water heater but that is usually more of a moldy egg smell. you mentioned you clean with bleach, i would inspect the caulking at the base of the toilet and see if you haven't cleaned so often around it that the caulking has worn off. the caulking is there so that anything that gets on the floor doesn't go under the toilet (like pee). the most likely of all is that there is a studor vent under the sink cabinet that is stuck closed. (i was typing the ideas as i was thinking them but i think this one is it) all fixtures need to pull air to drain. the studor vent has a diaphragm in it that allows air in but closes so the smell can't get out. if the vent is stuck closed, when you use the shower,tub or toilet they will pull the water out of the trap of the fixture they wash past. the shower likely washes past the sink and pulls the water out of the trap. as you use the shower the stink is coming out of the sink. (a stink sink if you will) when you go over to the sink it would be stronger since that is the source. after you run the water it would fill the trap and the smell would go away. later you may flush the toilet. again there is no where to get air so it may pull the water out of the tub trap or shower. the smell would continue until the trap is full of water again. the vent doesn't have to be a studor vent. the peferred venting method is to have the vent go out the roof. you could still have the same problem if the vent out
Expert:  Mike R. replied 2 years ago.
(i typed so much i ran out of space) cont.... is out the roof and blocked (pine needles etc) so how to fix it. if there is a studor vent under the sink (it may say something like "air admittance valve" on it. it is a cap on top of the drain kinda mushroom looking) then all you have to do is replace it. it could be as easy as unscrewing it and screwing the new one back in or cutting the pipe and glueing one back in. the roof vent could be tougher. i think you know what it would take to clean it out right? another way you can test for a venting issue is fill the sink just below the overflow. does it "glug" when you drain it? this is not a definite test since the sink may pull air from the overflow and won't "glug" but if it does then there is a venting issue.
Customer: replied 2 years ago.
Relist: Other.
The answer did not help narrow down possibilities. I will likely need to have a live consult
Expert:  Mike R. replied 2 years ago.
maybe my explanation was too long. i only explained in great detail what it was. please read it through i am sure that is what the problem is.
Expert:  Mike R. replied 2 years ago.
The short answer is the vent is blocked or stuck closed depending on what vent you have. When the skier drains it is pulling the water out of the sink trap. You can fix it by replacing the studor vent or getting someone on the roof to remove the blockage in the vent(if there is no studor vent under the sink)
Customer: replied 2 years ago.
Your suggestion about the venting problem, as you describe it, sounds to be in the ballpark. As far as I can tell, I do not have the studor vent, which may mean I need to examine the outside/roof vent. Since I am in a triplex, that's a longer term fix. Can you suggest any short-term solutions (even temporary) to the actual smell? It's always the same smell, it's always the same source, and the intermittent nature suggests it might be from accumulation of something. Would there be a point to try cleaning with bleach, vinegar, or some other chemical? If so, what would a potentially good target area?
Expert:  Mike R. replied 2 years ago.
when taking a shower you can let the water run lightly in the sink. if the shower pulls the water out of the trap the running water will fill it back up. you may want to do the same in the tub since the trap that is getting emptied may be in the tub. it all depends how the plumbing is ran. try that and see for sure that it stops the smell. if it does you can install a studor vent on the sink and that will take the place of the roof vent. that way no one has to fall off the roof!
Customer: replied 2 years ago.
So you do not think that any cleaning/chemical treatment can provide temporary solution/improvement?
Expert:  Mike R. replied 2 years ago.
no. the whole idea is to fill the trap with water again. when the trap is full of water the sewer smell doesn't get through. be certain you do not have a studor vent. if you are not sure take a picture under your sink and send it to me. look at both if you have two sinks. if you can't send the pictures put them on wikisend.com and copy and paste the link.
Expert:  Mike R. replied 2 years ago.
So how goes operation "stink be gone"?
Customer: replied 2 years ago.
Tried the test - during the use of shower, turned on water in both sinks we have in the bathroom, the only other drains there. The smell came on. Earlier in the day used the shower without doing that and there was no smell. Does the fact that the smell does not happen every time we use the shower tub fit with what you think might be happening. After all, if it is a vent problem wouldn't the trap be emptied every time? And I am pretty confident ther is no Studor vent.
Expert:  Mike R. replied 2 years ago.
Is there a tub, shower and two sinks? It won't always empty the trap when taking a shower. If there is a separate tub could be happening when the toilet gets flushed. How old is the house? Is there a crawl space under it or is the bath upstairs?
Customer: replied 2 years ago.
There is a bathtub, toilet and 2 sinks. The house is a 7 yr old town home, with all living space including 2 bathrooms on the second floor. There is no problem with the 2nd bathroom.
Expert:  Mike R. replied 2 years ago.
And the smell problem is new, right? It hasn't always been there?
Customer: replied 2 years ago.
It is recent. At least it became prominently noticeable recently.
Expert:  Mike R. replied 2 years ago.
Is the laundry room near? Does the smell ever coincide with laundry time?
Customer: replied 2 years ago.
No. It's always after the use of the shower, i.e. the bathtub.
Expert:  Mike R. replied 2 years ago.
You don't have well water right? The smell doesn't smell like natural gas does it? Also the other bath, does it get as much use? If you ran the shower in the other bath would the smell turn up there?
Customer: replied 2 years ago.
No well water, and the smell is not like natural gas. The second bath does not get as much use, but when we had guests there recently and they used it, there was no smell.
Expert:  Mike R. replied 2 years ago.
it has got to be a venting issue. especially since it goes away and is isolated to that bath. could you send a picture of the plumbing under the sinks? if the picture is too big to attach just download it on wikisend.com and copy the link. also a picture of the layout of the bathroom?
Customer: replied 2 years ago.
Here are some pictures:
http://www.mediafire.com/?g64igf70owhwetn,lch1ia2ozatvi8n,93845pibqcdl1ed,d5a75dabahnslr4,973ii2743u7vuxb,4ipsc230qt9ryk2,bcj7sckvczflcyg
Expert:  Mike R. replied 2 years ago.
is the vent on the wall in the last picture the bath fan? if it is can you send a picture of under the sink just the cabinet door open so i can see all the plumbing under each sink?
Expert:  Mike R. replied 2 years ago.
if the fan cover on the wall is not the fan the studor vent that is stuck closed is in there. replace the studor vent in there and the problem is solved. if it isn't, and that is just the exhaust fan then send me a picture of the plumbing under the sinks with the door open. i know this has been a lot of back and forth but we can figure out what it is. these are almost always difficult to figure out especially not being there.
Customer: replied 2 years ago.
Sorry, did not realize the URL got cut off. Here is the picture in that batch that you probably did not see:
http://www.mediafire.com/i/?bcj7sckvczflcyg

The second picture is the close-up of sink connection:
http://www.mediafire.com/i/?d5a75dabahnslr4

The fan cover on the wall is for the exhaust fan.
Expert:  Mike R. replied 2 years ago.
fill the tub with water and when you drain it get someone by the sink to see if you hear the water get sucked out of the trap. if you hear a suction sound out of either then the vent is blocked. you could fix that by cutting the pipe on that sink coming out of the wall, glue a tee and glue in a studor vent there. i am convinced there is a venting issue since the problem is intermittent. if it was anything else the smell would always be there.
Customer: replied 2 years ago.
My last question and I will thankfully accept your answer: the smell does not appear every time the shower/tub is used. If the venting were the one and only problem, wouldn't the smell happen every time?

I am away from home at the moment, so I cannot run the experiment right now. I will later though.
Expert:  Mike R. replied 2 years ago.
exactly the opposite. see if you follow my explanation. the vent allows air to let the plumbing drain. if not it would get air locked. the vent is almost always on the sink unless there is a separate vent. there are two types of vents the vent out the roof and the studor vent (which is a mechanical vent that fails and needs replacement eventually). if the bath is piped properly the sink would drain to the tub and maybe on to the toilet. i don't think it vents the toilet because of a code change that isn't worth explaining. so the sink vents the tub. the tub drains and pulls air from the sink vent. when you use the tub and the vent is blocked, the water in the trap on the sink gets pulled out. when you use the sink again it fills the trap and the smell stops. the trap in the shower always stays full. so, you shower, the tub drains and pulls the water out of the trap, you start to smell it, you finish the shower, go to the sink to brush your teeth, the smell is worse, you use the sink, fill the trap, the smell goes away.
Mike R., Plumber
Category: Plumbing
Satisfied Customers: 1416
Experience: 20 years of plumbing experience, including high end homes and service work.
Mike R. and 2 other Plumbing Specialists are ready to help you
Expert:  Mike R. replied 2 years ago.
Did you do the test? Fill the tub and listen for the sink trap to empty? Thank you for paying me but I really want the solution to be certain. Unless you are tired of trying. If that is the case I will be here when you need me.
Customer: replied 2 years ago.
I will try once I get home, which is the end of the week. I really appreciated your effort, especially when given only my verbal descriptions and pictures to go on. I will let you know what I find with my test. Thank you.
Expert:  Mike R. replied 2 years ago.
Great I won't give up if you don't! To sum up. There is sewer smell and it is constant. I don't think it is related to the pumping of the septic. The toilet seal was never good but when cleaning the bathroom floor the detergent ate away the caulking around the toilet. The more it smelled the more you cleaned. The neck of the toilet is directed down the drain so it doesn't leak but the wax seal isn't touching the toilet and the sewer gas leaks through. Replace the was ring with a larger, thicker ring and problem solved!
Expert:  Mike R. replied 2 years ago.
That last comment of mine was for another problem similar to yours. Disregard that. Keep me posted.

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