Fumes from Shower Drain

[BigJake]

Attached is a very rough diagram of the plumbing for our master bath and some pictures of the drain lines. I numbered sections to match the pictures to the diagram. There is a vent about 2 feet from the shower drain, it then ties into the drain from the hot tub (which also has a vent). It goes about 8 feet then has a 90 degree elbow turning it down (point # 3 on diagram/pictures) and runs horizontally another 8 feet where it ties into the 3" drain from the toilet. The toilet also has its own vent. The house was built in 1996. For years I thought the odor was from clumps of my wife's hair that would gather in the trap with soap scum. I would fish that out and the odor would decrease. I few months ago I put a basket strainer in the drain to catch the hair, but I'm still getting odor from the trap even when it is clean. I've tried pouring bleach in the trap and cleaning it with vinegar and baking soda. The odor only comes from the drain when the shower is in use and takes a couple minutes Is there something fundamentally wrong with the drain layout that is causing the trap to siphon or fumes to somehow gurgle up through the trap? I had changed the original trap with the white trap pictured to add the cleanout to make it easier to fish the hair out.

 

[breplum]

in pic 2, is shower drain's vent going up through the floor?
A p-trap with a vent and with water maintaining normal level should not be a sewer gas offender.
The slope overall sounds not like code 1/4" per foot, but, shouldn't be a cause of odors.
the toilet drain catching the 2" run is a "low heel" fitting without proper sweep and not code or correct, so sewage is running down the 3" drain, hitting the 2" branch and smearing itself into the 2" partially. Sure, running the shower should help clear that bad intersection...but maybe not.
That and many more items too numerous for this grouchy plumber to list is why I don't think a licensed plumber had anything to do this plumbing.

 

[BigJake]

Hi breplum,
Thank you for the response.

Yes, the vent indicated in Pic 2 goes up through the floor into the attic and connects to a common vent and goes out the roof. I attached Pic 8 that illustrates that section a little better. In Pic 8 the drain on the left is the drain from the shower, the drain on the right is from the hot tub. The drain from the shower actually only goes about 30" before dropping down about 4" with the two 45s then the hot tub drain connects with the Y. That initial 30" is pretty much level before hitting the 45s. The drain goes about another 4' then drops another couple inches with a 90 elbow to drop it to run horizontally below the floor joists . That section runs about 8' then connects to a fitting like the white fitting in the attached pic. I tried to get a better picture of the connection in PIC 9 but it is sandwiched between the I beam and ductwork. Is this what is called a "low heel fitting" ? I see what you mean about the potential of sewage splashing back into the 2" drain. Luckily there has never been any drainage problem with the toilet or the shower, just the issue of the fumes which I can't figure out. Should that 3" line have extended further up stream past the connection from the toilet before a 2" adapter was inserted? Do you have any suggestions on something I could changed that might eliminate the fumes? Is there anything about the current configuration that might cause the trap to siphon down enough to let fumes pass? Thank you!

Just to avoid any confusion, the 3" PVC on the wall in PIC 8 is not a drain line, it is for my dust collection system for my wood shop.
Also, I just pulled the hot tub drain free from the white hanger In PIC 8 and was able to lower the shower drain line to give the initial 30" (that was hanging level) to now have a 1/2" drop. I'll see if that makes a difference with the fumes tomorrow.

 

[BigJake]

So no one has any ideas on why I would be getting fumes from this shower drain?

 

[breplum]

If the shower drain has 1/4" per ft slope and the vent is normal, there ought to be no reason that the 2" p-trap would let in odors.
You might find a plumbing company to do a smoke test, wherein they pump a chemical non-toxic 'smoke' into the drainage system with vents capped off to reveal any potential leaks, say from a break in a pipe in the wall.
I have a neighbor who smells odors that we've never been able to figure out. She did not smoke test.

 

[BigJake]

If the shower drain has 1/4" per ft slope and the vent is normal, there ought to be no reason that the 2" p-trap would let in odors.
You might find a plumbing company to do a smoke test, wherein they pump a chemical non-toxic 'smoke' into the drainage system with vents capped off to reveal any potential leaks, say from a break in a pipe in the wall.
I have a neighbor who smells odors that we've never been able to figure out. She did not smoke test.

The odor happens only when using the shower. I would think that a break in the vent line would cause an odor all of the time? And the odor is inside the shower, so definitely seems to be coming from the drain. The only other thing I can think to try is going up on the roof and listen to the vent to confirm I hear water running, to confirm the vent is not blocked.. The builders did do some stupid stuff in this house. Last year I discovered that the ceiling vent in the master bath did nothing. There was no exhaust duct connected to the fan in the attic and the fan was totally covered over with insulation, so doing nothing, I connected an exhaust duct and vented it thru the roof. Another bathroom has an exhaust duct connected to the fan but it just runs to the eave, which is not to code. I still have to run that one thru the roof. At least it is just a guest bath, so rarely used. That's what you get for $400K...

 

[mark3885]

I’m not a plumber but I’ve had a similar situation. When our daughter was living at home the shower trap was usually partially clogged by hair, along with certain hair products, she would complain about an odor when she showered. Problem resolved itself when she got married and moved out. Apparently, she used so called organic hair products which contained milk proteins etc. since she moved out , lower water bills and lower gas bills and no odor. Just thought I would mention it.

 

[BigJake]

I’m not a plumber but I’ve had a similar situation. When our daughter was living at home the shower trap was usually partially clogged by hair, along with certain hair products, she would complain about an odor when she showered. Problem resolved itself when she got married and moved out. Apparently, she used so called organic hair products which contained milk proteins etc. since she moved out , lower water bills and lower gas bills and no odor. Just thought I would mention it.

Yes, for years I assumed it was the gobs of my wife's hair that would collect in the drain with soap scum. That stuff would smell pretty nasty when I pulled it out. I put a basket strainer in the drain a few months ago that captures the hair and empty that. I've poured bleach in the drain and also tried cleaning it with baking soda and vinegar, but still get odors when the shower is used so I'm stumped. Last week I opened the cleanout on the bottom of the drain emptied the water in the trap into a bucket. It had a faint odor. I left the trap without water for a while to see if I got sewer gas through the empty trap and was surprised that I could barely smell anything but I get a strong odor when using the shower.

 

[GReynolds929]

Your pictures don't show much. Where is the shower trap and drain. I don't see a trap in those pictures.

 

[BigJake]

Your pictures don't show much. Where is the shower trap and drain. I don't see a trap in those pictures.

I think you missed the first post with all the labeled pictures

 

[GReynolds929]

I think you missed the first post with all the labeled pictures

Yup I sure did.