Sewer smell - WTF ?

[amboy49]

I’ve lived in my single story ranch home for over 30 years. The house is on a crawl space and I have a septic system that is the same age as the house. The septic has always worked properly and I recently had the septic tank pumped. With that being said I am experiencing a strong sewer smell in one of the bathrooms. This problem has occurred for several years ( I don’t know how long this has been going on but quite awhile). I’ve tried tracing the cause of the problem without success. Last week I pulled the toilet up and replaced the wax ring with no change. Last year we had our roof reshingled and the roofers installed new bathroom vents through the attic and up through the roof. The odor was historically present occasionally before any of that was done.

The crazy part is that the smell is not constant. It seems to be much more prevalent during the summer. Last week when we got quite a bit of rain the odor stopped for a few days. All of the plumbing appliances are used every day - toilet, sink, and shower. The bathroom with the problem smell is adjacent to our other bathroom and there has never been the same smell evident there. I’ve been in the crawl space and checked the pvc connections and nothing was evident re: a disconnected pipe.

I’m at a loss to figure out how the odor is working it’s way into the bathroom. The crazy part is the odor is not constant. Hoping someone might have a suggestion as to what to do or where to look. My wife is about to the point where she will close that bathroom off and make me start using an outhouse outside ! I’m not opposed to calling a plumber if that’s what it will take. However, if it’s something reasonably simple I’d like to save the expense if possible.

Thanks in advance for any suggestions up to and including suggestions for a reliable plumber I could call if necessary.

 

[Rookie]

When is the last time you pulled the strainers from the sink/shower?

 

[GLOCKMAN23C]

Is there a trap on your water heater pop-off valve drain?

 

[510picker]

I’ve had similar issues with the cause being my shower drain. Running some good drain cleaner through it solved the problem.

 

[LarryC]

You may have a leak in one of your "traps" either on the sink or shower / bath. If there is a leak and the trap empties the sewer gas can vent into the house. Chances are you can see your sink/vanity as it should have either a P-trap or S-trap under the sink. The bath /shower would be under the house.

 

[GLOCKMAN23C]

Is there a vent fan in this bathroom, if so where does it vent?

 

[K_W]

You've got a restriction somewhere in your vent stack and too small (or dry) S bend in the pipes. Any movement of water in a pipe creates air movement in the direction of the water flow.

I had a similar problem when my stack clogged with leaves and when the washer would discharge the airflow would suck the water from the kitchen sink S bend trying to equalize air pressure, fortunately there's no on that side of the house.

I cleared mine with a shop vac by alternating suction and blowing down the pipe while running the water in the sink.

 

[1911ly]

You've got a restriction somewhere in your vent stack and too small (or dry) S bend in the pipes. Any movement of water in a pipe creates air movement in the direction of the water flow.

I had a similar problem when my stack clogged with leaves and when the washer would discharge the airflow would suck the water from the kitchen sink S bend trying to equalize air pressure, fortunately there's no on that side of the house.

I cleared mine with a shop vac by alternating suction and blowing down the pipe while running the water in the sink.

This! And if you have a bath tub or sink you don't use often the gasses can come back threw that if the trap is dry.

 

[1DOWN4UP]

This! And if you have a bath tub or sink you don't use often the gasses can come back threw that if the trap is dry.

. This^^^^^

 

[amboy49]

Thanks for all the replies -

Some add’l info:

I recently replaced the vanity in the bathroom with a taller one. I didn’t have to change anything - the pvc connections were expandable and didn’t need replaceming. The smell was present before I replaced the vanity.

The roofers ran new vent pipes through the attic and out through the roof. The old vent pipe from the ceiling out through the roof is still up there but I don’t know how or if the roofer blocked it off. I’m pretty sure they didn’t just run the new vents from the old vent. They ran flexible insulated piping from inside the attic and connected to the exterior roof vents. ( Before the roofing job there was only one vent going through the roof - now there are two vents side by side through roof adjacent to each other. The bathrooms share a common wall ). The smell was evident before the roofing job.

Because we use the toilet, sink, and shower daily there isn’t much, if any, probability any of the drains are running dry unless an S trap below the floor is leaking.

I’ve been in the crawl space on different occasion(s) and haven’t noticed any leaks (wet spots in the pea gravel. I think I need to crawl under there once again to check the pipe connections. However, this issue has been going on for quite some time. I would have thought I would have observed a leak if there was one but then again, I don’t know what I’m looking for either.

I’ll study the diagram to see if I can figure out where there may be an issue.

If I could narrow it down to whether the problem is below the floor or above the ceiling that would at least help me try to fix the problem.

Again, thanks all for the comments. I’ll keep trying to figure it out.

 

[amboy49]

Is there a vent fan in this bathroom, if so where does it vent?

Both bathrooms have a vent fan into the attic - which I’m pretty certain vent out through the roof.

 

[DRAIN SURGEON]

Check your shower to make sure it really does have a trap. S traps can sometimes siphon themselves dry by the water draining so fast it all drains out. They're against code in some other states , like Florida where I got my license.

 

[Clay Pigeon]

I would do a simple smoke test, If you don't feel comfortable you can hire a plumber to do it. [video=youtube_share;y5rANaDEJm8]https://youtu.be/y5rANaDEJm8[/video]

 

[Dead Duck]

Have you recently changed your brand of deodorant?

 

[WanderingSol07]

Your attic sounds suspicious, no vents should end in the attic, you get sewer gas coming out of vent pipes! All of your vent pipes coming out of the ceiling should go through the roof and vent outside.

 

[Clay Pigeon]

Your attic sounds suspicious, no vents should end in the attic, you get sewer gas coming out of vent pipes! All of your vent pipes coming out of the ceiling should go through the roof and vent outside.

Read the first paragraph in the OP again...

 

[IndyTom]

I've got a bathroom that doesn't get a lot of use. If I ever catch a whiff of anything in it, I'll make sure to run the faucets to make sure there is water in the pipes to keep the stinkies from escaping.

 

[breakingcontact]

dry traps?

any hoses stuck down too far into drains?

 

[Dead Duck]

Did you try flushing down a bowl of uncoiled white rice?

 

[GLOCKMAN23C]

Both bathrooms have a vent fan into the attic - which I’m pretty certain vent out through the roof.

Check for places where water can condense and collect. If this is happening, it can smell like sewer gas or like something died. I had this happen and it was always worse in the summer. I cut holes in walls looking for dead vermin and moisture.