Why is my shower drain gurgling when flushing toilet

[Scottyk75]

Hi,

I recently got around to putting in a bathroom in the basement of our 10 year old home (Toilet, sink, and Shower). It was relatively uncomplicated as all of the plumbing was roughed in by the builders (shower drain, toilet pipe, and sink drain.) They all tied into the vent pipe that I could see going up through the floor to the upper levels. Everything works well. The toilet flushes great, and the shower and sink drains well. However, I noticed that the shower drain makes a gurgling sound for a few seconds when I flush the toilet or drain the sink. It makes the same gurgling noise if one of the upstairs toilets are flushed, but it’s not nearly as loud or noticeable. Neither of our upstairs bathroom drains makes this gurgling noise. It’s only the shower in the basement. Also, I’ve had the shower in for quite a while and I never noticed it making any gurgling noises until we put the downstairs toilet in. Any idea what could be causing this? Do I have something to worry about? I’ve read that a blocked vent on the roof could be causing this, but wouldn’t that affect every bathroom in the house of that were the case? Thanks in advance for your response.
PS- Yes, traps were installed in the shower and sink.

 

[hj]

The most likely problem is that the did NOT vent the shower properly. They may have used the "no vent needed if it is within 6' of the main" "rule" that many DIYers quote as gospel.

 

[Sponsor]

 

[Jadnashua]

Incorrectly installed, or missing vent lines for the basement fixtures can cause that. An unvented fixture actually can drain better (in some cases) that one with a proper vent, so a clogged one is not a reliable link to gurgling. Without knowing what is under the floor, it's hard to tell. A picture of 'before' during construction might show if there were any vents installed.

 

[Scottyk75]

Ok, so I had someone take a peak at this, and it seems the sound that I am hearing is not gurgling at all. They said it's just the sound\echoe of water running through the pipes (all the plumbing in the house converges right in this bathroom). I also asked if the P-trap directly beneath the shower should block that noise. He said not necessarily, and also said there isn't a P-trap directly beneath the shower- but there should be one somewhere beneath the concrete slab and it wouldn't have passed ispection when the house was being built if there wasn't. There's absolutely no smell or oder coming from the shower drain, so I am inclined to agree that there must be a trap somewhere?? In addition, even when we uncapped the toilet drain pipe to put the toilet in there was absolutely no odor which surprised me.Seems like they must have put something under that slab that's really keeping any sewer oders out???

 

[Jadnashua]

Not all sewer lines smell all of the time. Plastic pipe is noisier than CI, but once underground, that provides a lot of insulation, and you'd probably couldn't hear it. But, above ground in the walls, plastic pipes are much noisier than CI, and it's still used where that is an issue - costs more since it's harder to work with, not counting the material cost.

If you can't see water looking down the shower pipe, you may eventually end up with some smells even with a p-trap...that longer pipe has more surface area to accumulate soap scum, hair, etc.

 

[Edna]

The most likely problem is that the did NOT vent the shower properly. They may have used the "no vent needed if it is within 6' of the main" "rule" that many DIYers quote as gospel.

Not all sewer lines smell all of the time. Plastic pipe is noisier than CI, but once underground, that provides a lot of insulation, and you'd probably couldn't hear it. But, above ground in the walls, plastic pipes are much noisier than CI, and it's still used where that is an issue - costs more since it's harder to work with, not counting the material cost.

If you can't see water looking down the shower pipe, you may eventually end up with some smells even with a p-trap...that longer pipe has more surface area to accumulate soap scum, hair, etc.

what if there is an odor along with the flushing "echo"? What could this mean? I can't remember if there was a vent pipe going up to upper levels before the basement walls were erected and covered. Do you have pictures of shower/plumbing venting that you can share?

 

[hj]

I quwation whether that "someone" who advised you really knows what he is talking about, since none of it makes logical sense. The shower trap may NOT have been installed during the initial installation, (it would NOT be "somewhere under the floor"), because they would not have known where the shower drain would be located, and if not, and if you did not install one, then that shower may not have a trap on it.

 

[Reach4]

Ok, so I had someone take a peak at this, and it seems the sound that I am hearing is not gurgling at all. They said it's just the sound\echoe of water running through the pipes (all the plumbing in the house converges right in this bathroom).

I hope you find that to be good news.

You can reduce sounds a bit with sound absorbing curtains or panels to reduce the sounds bouncing around the bathroom.

 

[Jadnashua]

The best place for a shower drain trap is directly beneath the drain itself. Offsetting it to the side can be problematic.

If you place something light like a sheet of tissue paper on top of the shower drain then flush the toilet, see if the tissue moves. It might move very slightly with a trap, but it shouldn't move much at all, if any. Hearing water flowing in a pipe buried under concrete through a water filled trap would be quite muffled, and often inaudible.

 

[Edna]

The most likely problem is that the did NOT vent the shower properly. They may have used the "no vent needed if it is within 6' of the main" "rule" that many DIYers quote as gospel.

The best place for a shower drain trap is directly beneath the drain itself. Offsetting it to the side can be problematic.

If you place something light like a sheet of tissue paper on top of the shower drain then flush the toilet, see if the tissue moves. It might move very slightly with a trap, but it shouldn't move much at all, if any. Hearing water flowing in a pipe buried under concrete through a water filled trap would be quite muffled, and often inaudible.

i did this with the tissue over the shower drain, the tissue moved as if it was being blown from below as the gurgling sound was made after flushing the toilet. Does this confirm that there is no P-trap below the shower? My bath fixture drains (shower, toilet, sink) are all within 5 feet of the closest main drain. Again, I can't remember if there was an exhaust pipe going up through the basement ceiling to the upper floors. We built the basement from slab floor and cinder block walls, but the drains were installed 19 years ago and capped off. I just don't know if the shower has a p-trap. The odor will not subside unless a cleanser is used every time the toilet is flushed. The drain doesn't go straight down but goes down at an angle. We did not think we needed to dig up the foundation to check for a trap, that the appropriate exhaust and drain systems would have been done in 1996 to pass inspections.

 

[Jadnashua]

With a p-trap filled with water, moving air in front of the waste going down, the water might move very slightly and therefore push a little air, but nothing like what you are describing. It really sounds like there is NO p-trap in there, and this will persist until you tear things out and install one.

Take the grate off, take something like a hose and push it down there. It will be hard to push it through a p-trap. Keep pushing while it is moving relatively freely, and see how far you can go before it stops. A snake would go through a p-trap, but you'd still be able to tell you were going through something like that verses a straight pipe or around a bend of a fitting.

It is very common to install the pipes, but NOT to actually install the trap until the shower is actually installed since almost every shower would require that in a different place unless you wanted to customize the pan to the drain location.

 

[WorthFlorida]

Other than a p-trap problem, could it be that the air vent pipe has some restriction since anything can fall or get into the pipe from the roof. For a large volume of water from a flush from a toilet is a problem but a trickle of water from the shower or sink it's OK.

Does the vent pipe have any bends in it from the basement ceiling to the main vent pipe?