Sewer smell from bathtub

[saxsellers]

Recently bought a 100+ year old house with basement. When someone takes a shower or bath, the main floor seems to get a strong sewer smell, but none in the basement. We still smell it after coming home from work in the afternoon, but very strong with a bath. The stench really comes through the drain line of the tub--through a plumbing access panel into a closet (but not into the bathroom). We are on city plumbing.

Drain line from the sink, tub, and toilet all go directly into the main line with no indoor venting pipes. The only vent is outside coming out of the roof....4 inch vent. We never noticed this smell in the winter. Now that it's hot, it's really pungent. Could lack of venting be the issue? Other ideas?

As always, thanks for the help!

 

[Dj2]

You can try cleaning the drain with bleach, vinegar, baking soda or any other commercial cleaner. The stench is bacteria, which can be brushed off.
YouTube has some good videos on the subject.

 

[Sponsor]

 

[saxsellers]

You can try cleaning the drain with bleach, vinegar, baking soda or any other commercial cleaner. The stench is bacteria, which can be brushed off.
YouTube has some good videos on the subject.

Thanks! Will give that a try.

 

[saxsellers]

We put some vinegar and baking soda, as well as drain cleaner down the drain, but smell still shows up about once or twice a week. If it's anything related, the sink gurgles when draining the tub.

I've attached a photo of the tub drain from the basement. Would the horizontal run before the trap have anything to do with the smell? I have no clue...Just wondering?

 

[Terry]

If the sink gurgles when draining the tub, add an AAV to it. The trap may be siphoning otherwise.
Each trap should have a vent to prevent siphoning of the trap. In a wet vent situation, often the lav is used as the vent, assuming it's run with 2" on the wet portion and it's vented. The lav trap making noises like that my indicate that it's not vented.

 

[saxsellers]

If the sink gurgles when draining the tub, add an AAV to it. The trap may be siphoning otherwise.
Each trap should have a vent to prevent siphoning of the trap. In a wet vent situation, often the lav is used as the vent, assuming it's run with 2" on the wet portion and it's vented. The lav trap making noises like that my indicate that it's not vented.

After reading your post and doing a little more digging, the trap under the sink is an S-trap, not a P-trap, which could very well cause the siphoning. I do know that all 3 drains--toilet, lav, and tub--go directly to the main line, which has a 4" vent out the roof. However, none of them has a vent anywhere before the 4" roof vent (unless the tub overflow acts as a sort of vent).

So it sounds like you would recommend adding an AAV under the sink and changing the S-trap to a P-trap? As always, thanks for the help!

 

[Terry]

The overflow does nothing for venting, so getting rid of the S trap and adding the AAV may do it.

 

[saxsellers]

The overflow does nothing for venting, so getting rid of the S trap and adding the AAV may do it.

Will give it a try. Thanks!

 

[saxsellers]

Took care of the AAV on the bathroom sink, but still have the smell. That narrows it down to the tub or toilet! Seems to get stinky after a bath.