Another plumbing mystery.

[N80]

I live in a 30 year old house on a septic tank and just started having a strange problem when I flush the upstairs toilet. As the flush is almost complete, even after the flapper has closed I get a deep, gurgling, drumming noise that comes from the shower drain. It lasts for several seconds and it is loud. If I hold my hand tightly over the shower drain I can feel a push of air pressure when this noise starts. The toilet, which is an old high flow, flushes and drains perfectly. The shower, also high flow, and sink drain perfectly. The other upstairs toilet drains fine and causes no noises. I'm stumped. Any ideas?

 

[EddieWalker]

Sounds like your vent is plugged up and the drain from the shower is acting like a vent, but because there is a trap under it, it's pulling the water in the trap. When the toilet flushes, it fills the pipe with a lot of water real fast, so the trap is critical on toilets. More then any other trap. All that water creates a seal in the pipe and it will pull air from behind it to allow it to flow. If your trap is plugged, then it's going to pull air from whatever else is behind it. In your case, it sounds like the shower drain is where it's getting the air, after it pulls the water out of your trap. I wonder if you can smell sewage from the shower after this happens? Of course, there might still be enough water in the trap to keep out the gases from your tank, and some tanks don't smell as bad as others.

Look at your vent, maybe send a hose down it and turn it on to flush out what's in there. Or run a snake down it to see if there is anything in there.

Good luck,
Eddie

 

[MossRoad]

Your vent stack is probably plugged.
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[MossRoad]

Ha! Eddie beat me to it! :thumbsup:

 

[N80]

I thought of that too but it is pushing air out of the shower drain, not pulling it in. And when the vent stack in my cabin was clogged the toilet would not flush completely. This toilet is flushing great. And, when I sealed the shower drain with my hand it still flushed fine and still made the noise. There has been no odor, even sniffing the shower drain.

Anyway, the vent stack was my first thought, that's why I tried flushing with the shower drain sealed. However, I will still check it.....I have a snake.....or I'll get someone else to, I hate going on the roof of my house. I'm a chicken when it comes to heights and it is steep and way up there.

Just out of curiosity, what would block a vent stack up on a two story house.......?

Come to think of it there were tons of fireworks the night of the fourth....what are the odds on that?

 

[rekees4300]

Just out of curiosity, what would block a vent stack up on a two story house.......?

Could be a wasp nest.

 

[N80]

Me on the roof with a wasp nest......I'm envisioning a Chevy Chase or Three Stooges sort of moment....

 

[Pops15]

If it's pushing air out of the shower drain it could be a plugged or nearly plugged drain.

 

[Transit]

I am thinking maybe a bird got into the vent stack. One of the functions of the vent stack is to break the vacuum caused by the falling water in the waste pipe. If the vent stack is plugged, than air will be drawn in elsewhere, the shower drain.
You could try blocking the shower drain and other drains and giving all the toilets a good flush pulling whatever is in the stack along.
:thumbsup:

 

[Egon]

Hmm, got a friend with exactly the same problem. he checked his vent. It was clear. Dug up his septic line. it was clear too. He still has the gurgle.