What the heck is that smell

[Steve McCarron]

About 6-8 months ago, I started getting a really strong, musky smell in my upstairs bathroom. After a few tests, I found that the smell was coming from the drain in the bath tub. Simple fix, leave the plug in. I would like to know what is making the smell as sometimes one of us may not remember to put the plug back in. The tub has a proper trap, likely a P trap as the pipe goes into the side of the 3 inch main line. The system is vented thru the roof just above the bath room.

The tub seems to drain fine and the toilet flushes fine, both are side by side. I have not snaked the plumbing yet as I have a very weak stomach when it comes to pulling the snake back out covered with who knows what. The trap is not leaking as it would show up on the ceiling tile in the bed room below.

So, is something sucking the water out of the trap which is designed to keep the smell from coming up out of the septic tank?

Anyone have any suggestions as to what might be the problem and how to fix it. As I am on a septic system, I would rather not use harsh chemicals to treat the problem.

I will sure appreciate and offerings.

Thanks for reading

[Ron F]

Steve I had the same problem years ago and started adding a product called Septal to the toilets once every couple of months
It cured the problem and this product is not a harsh chemical
Ron

[stevem]

check for a blockage in the vent pipe above the tub and toilet

[OttawaP]

Steve has it right....

[Barry in London]

If there's a blockage in the vent pipe the tub, sink and toilet will drain slowly and probably gurgle and burp. If your vent pipe goes straight to the roof you could go up and pour drain cleaner down the vent then flush the toilet, drain the sink and the tub. If it's close and you don't want to use chemical, get a long stick (like quarter round) and poke it down through the vent pipe to bust up the blockage. Had this problem with my last house and the stick down the drain pipe worked great. Problem was solved. In my case the previous owners of my last home must have poured a lot of fat (like bacon fat) down the drain and it plugged the vent pipe.

[Bill R.]

Run some water in the tub to fill the trap then flush the toilet and listen for the water in the tub trap to be pulled out. This could be caused by a pluged vent but most likely the vent froze up during the winter cause the trap to be sucked dry. Any vent less than 3" can cause this during cold snaps.

Bill R

[Mike in Waubaushene]

I'm not saying its not possible, but how can a vent pipe get plugged above the level of the drains tied into it, unless the vent goes to the lowest point of the system. Seems like if there was any material introduced from a drain source and it flowed up, there would be an overflow somewhere. On rare occasions, a bird could build a nest where it is open at the top, or a squirrel could slip in. But the sewer gases coming out is enough deterrent to keep most kritters away.
Mother in law has same problem. In the vent stack, I dropped a water hose with a high pressure nozzle all the way to bottom and turned it on. Slowly pulled it back out. Everything seemed clear going in and out. No changes in anything. All drains are fast. Smell goes away for a while, then reappears a few weeks later for a spell. It's a head scratcher, for sure.

[stevem]

a blockage above a toilet can be from many things, stuff does get into plumbing stacks from above the roof

i worked one summer for a roofing company, and the favourite place for cigarette butts was down the "stink" pipe!!

in many houses, up in the attic, there will be horizontal runs of vent stack to tie all of the vents into one roof penetration. these horizontal runs are supposed to sloped to some degree and well supported to prevent sagging

that would be my first check, i know our house has one stack for three bathrooms and the kitchen and does have some horizontal runs in the attic and abs pipe will sag under its own weight especially in a hot attic space

[Barry in London]

I'm not saying its not possible, but how can a vent pipe get plugged above the level of the drains tied into it, unless the vent goes to the lowest point of the system. Seems like if there was any material introduced from a drain source and it flowed up, there would be an overflow somewhere. On rare occasions, a bird could build a nest where it is open at the top, or a squirrel could slip in. But the sewer gases coming out is enough deterrent to keep most kritters away.
Mother in law has same problem. In the vent stack, I dropped a water hose with a high pressure nozzle all the way to bottom and turned it on. Slowly pulled it back out. Everything seemed clear going in and out. No changes in anything. All drains are fast. Smell goes away for a while, then reappears a few weeks later for a spell. It's a head scratcher, for sure.

Hi Mike. If you're referring to my post, I don't know how it was possible. I can only guess that over time pouring fat down the drain along with water filled the drain pipe and some of it collected at the vent pipe. Eventually it plugged the pipe. I'm assuming it was grease because after poking the stick down it, it came up with what looked like thick grease (like bacon fat) on the end of the stick. I did try drain cleaner down the sink but it didn't do anything.

[Ryan Shervill]

There is a *very* good chance that you guys are over-thinking this....the talk seems to have shifted to vent stacks and the like, but I'd bet dollars to donuts that the "musty" (notice he didn't say "sewage") smell coming from the tub drain is caused by....wait for it....the tub drain

The fact is that if he's. It smelling sewage, the trap is working fine...but what the trap itself smells like is going to be the issue.

In that drain, wrapped around any internal screen and/or plug mechanism, and even coating the trap itself will be a congealed mass of hair (especially if there are any long-haired family members), old soap, lint, and a whole assortment of other nasty byproducts of the bathing process. These are what causes that musty/moldy smell (if you took a pail, added a mass of hair/etc, added some dirty water, put it in the dark and kept it nice and warm/wet for a few months you can bet it'll smell too )

If it were my bathroom (and with three long haired females sharing one tub, believe me...it has been) I'd clean out the drain. If you have a pop-up drain you just unscrew the cap and remove the large screw underneath which will allow you to pull out the cartridge (as well as a bunch of the slime/hair)....if you have a conventional drain just look down it with a flashlight...anything that is hanging off of the internal screen will need to be removed either mechanically or chemically (or both). A piece of coat hanger with a book at the end works OK for the hair, and the soap scum can be removed with a few pots of boiling (as in literally boiling) water poured down.

Drain cleaners will work as well, but be forewarned that they can wreak havoc on the finish of some tubs, especially acrylic tubs.

So my advice: put a clothespin on your nose to help with that weak stomach you mentioned, buck up and clean out that drain

Ryan

[ArtMulder]

There is a *very* good chance that you guys are over-thinking this...
...
So my advice: put a clothespin on your nose to help with that weak stomach you mentioned, buck up and clean out that drain

+1 on this.
Start with the simple approach.

With long hair in the house we just accept that I have to disassemble the pop-up in the sink and clean it out about twice a year.
...art

[Chimera]

My father always made me clean out the bath tub drain because I was the one with the big mop of long hair that plugged it...YUCK!!!!

Now I always use a little stainless steel strainer (from the dollar store, they come in a two pack, not the screen one but it has little holes in it) and clean it out after every shower....so much easier and a lot less smelly...

[Steve McCarron]

Hi all: Thanks for all the tips. Musky may not be the right word as I have not smelled the raw sewage in my septic tank in a while. Some of you guys mist be mind readers. The vent is 1 1/4 or 1 1/2 up thru the 4 inch wall with a 90 degree elbow, a vertical run of about 8 to 10 feet, then another 90 up several feet to an enlarger and out thru the roof as 3 inch pipe. Yes it may be sagged as it is sitting on the top of 4 inches of pour in insulation. I think the garden hose idea will be my first option. Maybe I will make a wood fire tonight (hot water heating for the house as well as domestic hot water. With a good fire, my hot water can get pretty hot. Or a kettle of boiling water, good idea as well. No such thing where I live as high pressure water, 40 pounds max from my pump. Maybe I will drag the pressure washer up onto the roof, NOT. Drain o may do the trick as well. Maybe I will plunger the trap as well.

My hair is maybe 3/4 of an inch long when it gets really long, and the wife will not wash her hair in the tub. Maybe it is all toe jam, LOL

Thanks for the great tips. I will wait till the wife is home before I venture up onto the roof of the two story house.

I will let you all know what I find in a day or two.

[Steve McCarron]

Another quick comment. Someone mentioned bacon grease. It will definitively plug drains. About a year ago here in Halifax, everyone in an area was complaining about slow drains and sewage back ups. Once it was investigated, the city had to did up part of the main sewer line in the street as well as the branch pipe into a business. That business was a restaruant and yes, there had been dumping hot bacon grease down the drains for a long time. So that can happen