Sewage and Drain Flies breeding in Laundry Floor Drain

[Larry Williams]

Hello all -
I've got an ongoing problem that I'm hoping somebody on this forum will be familiar with. I began noticing this problem when I started getting those dreaded drain flies in the laundry room. In this laundry room, there is a floor drain (the lowest point of my split level home) that is connected to the sanitary sewer line going to the street. The laundry floor drain consistently gets back-flow from the upstairs toilet (the floor above the laundry room). The upstairs toilet expels water through a gravity fed drain pipe going down vertically and then turns horizontally. When the waste water makes that horizontal turn and passes through the what I'm assuming is a Wye connector under the concrete that connects the upstairs piping with the floor drain, some of the waste water back-flows into the floor drain trap. I see shreds of toilet paper in the bottom of the floor trap after I flush upstaris. I've never had the floor drain back up to the point where sewage was all over the laundry floor. Anyhow, when I dump clean water down the floor drain, that pushes the sewage out of the trap and into the line going to the street with no problems. The trouble is that I have to do this every week or else drain flies start breeding in the sewage just sitting there at the top of the trap. The trap holds an ample amount of water so I'm pretty sure the trap isn't broken and I've checked it over a few days to make sure there wasn't a slow leak.

I have had 3 plumbers come out and none of them could tell me what the issue is. They had done a camera inspection in the cleanout in the front yard and the waste water was exiting properly - no roots or anything. Just to cover my bases, I had them rod all the lines but they didn't come across a clog. It's this annoying situation of back-flow into the floor drain that is causing me to lose my sanity. I installed a green drain rubber one way check valve on top the drain which keeps gases out and any drain flies out but hoping for more of a long term solution.

Hoping someone can shed some light on what in the world my problem might be.

 

[Reach4]

When the waste water makes that horizontal turn and passes through the what I'm assuming is a Wye connector under the concrete that connects the upstairs piping with the floor drain, some of the waste water back-flows into the floor drain trap.

Not a wye, or the wye is pointing the wrong way?

Just to cover my bases, I had them rod all the lines but they didn't come across a clog

Did they rod through the closet flange? If a wye were backwards, the cable from the toilet might not have made it to the exit.

They had done a camera inspection in the cleanout in the front yard and the waste water was exiting properly

I think the camera work should be from the floor drain and the toilet.

I am not a plumber.

 

[Sponsor]

 

[Cacher_Chick]

Without being able to see the piping layout we can only speculate. Every fixture trap should have a vent prior to the connection to the main line, including the floor drain. If the wyes are facing the right direction and the system is clear of restrictions and properly pitched to drain, there would never be such a situation.

 

[Larry Williams]

Not a wye, or the wye is pointing the wrong way?

Did they rod through the closet flange? If a wye were backwards, the cable from the toilet might not have made it to the exit.

I think the camera work should be from the floor drain and the toilet.

I am not a plumber.

Reach 4 & Cacher_Chick - thank you for replying to my post. I really appreciate it. A few of things -

1. The plumber did rod from the cleanout access in the stack which is between the toilet upstairs and the floor drain. The snake did make it to the other cleanout access outside the house in the front year.
2. Is there a diagram you can point me to of a backwards wye?
3. Is there a way to tell if the floor drain has a vent without breaking up the concrete? In other words, what are the symptoms of an un-vented drain.

 

[Reach4]

2. Is there a diagram you can point me to of a backwards wye?

Here is what I had in mind.

 

[Larry Williams]

Thanks for the picture - this really helps out. I can rule out a backwards wye as I think much more would come up through the floor drain! I had the plumber out this morning and he thinks that the floor drain was never vented to begin with as the house is almost 50 years old. That would explain only a small amount of waste water coming into the trap. Anyhow, before he starts breaking up concrete - he's going to camera the lines from the roof stack to make sure there are no other issues. Thanks again!

 

[Raquelg0910]

Larry Williams hi did you fix your issue? i have the same problem and cant find what to do

 

[Raquelg0910]

Hello all -
I've got an ongoing problem that I'm hoping somebody on this forum will be familiar with. I began noticing this problem when I started getting those dreaded drain flies in the laundry room. In this laundry room, there is a floor drain (the lowest point of my split level home) that is connected to the sanitary sewer line going to the street. The laundry floor drain consistently gets back-flow from the upstairs toilet (the floor above the laundry room). The upstairs toilet expels water through a gravity fed drain pipe going down vertically and then turns horizontally. When the waste water makes that horizontal turn and passes through the what I'm assuming is a Wye connector under the concrete that connects the upstairs piping with the floor drain, some of the waste water back-flows into the floor drain trap. I see shreds of toilet paper in the bottom of the floor trap after I flush upstaris. I've never had the floor drain back up to the point where sewage was all over the laundry floor. Anyhow, when I dump clean water down the floor drain, that pushes the sewage out of the trap and into the line going to the street with no problems. The trouble is that I have to do this every week or else drain flies start breeding in the sewage just sitting there at the top of the trap. The trap holds an ample amount of water so I'm pretty sure the trap isn't broken and I've checked it over a few days to make sure there wasn't a slow leak.

I have had 3 plumbers come out and none of them could tell me what the issue is. They had done a camera inspection in the cleanout in the front yard and the waste water was exiting properly - no roots or anything. Just to cover my bases, I had them rod all the lines but they didn't come across a clog. It's this annoying situation of back-flow into the floor drain that is causing me to lose my sanity. I installed a green drain rubber one way check valve on top the drain which keeps gases out and any drain flies out but hoping for more of a long term solution.

Hoping someone can shed some light on what in the world my problem might be.

did you fix your problem same is happening to me now

 

[John Gayewski]

I think a trap primer attached to thre toilet would be an easier solution than breaking up concrete.