Drain Fly infestation advice

[EdwardSoftly]

Hey all,

We have been dealing with a drain fly infestation for over 5 years now and we are beyond our wits. Quick background…..Our home was built in the 60’s, we are on a slab, ranch style. 2 bathrooms. We’ve had plumbers come and snake/clean drains. We’ve had plumbers just use smoke bombs on the roof in the 2 vents we have (one over bathroom/one over kitchen). The smoke did reveal a loose connection to bathroom drain (comes out of the floor) so that was re-done and is now nice and tight with no smoke. However, after the second smoke test to ensure a proper seal, no smoke came through but the strong silver smell just radiated in the back bedroom next to the bathroom. Plumber also saw no smoke in the attic so he was at a loss. We still suck up 50 drain flies a day and they just keep coming. They are in every room in the house but the majority are in the kitchen area/family room (one large room). No smoke came out of the kitchen drain or walls so we are left scratching our heads. We had to have a gas line that cracked replaced several years ago. We also have radiant heat under the slab and a line cracked several years ago that we had to have fixed. Tore up concrete to fix. So, my thought is the house has moved, cracking those other 2 areas, I’m sure there is a cracked pipe under the slab somewhere that is allowing these things to come up and go wherever they will. But the smoke revealed nothing. Can smoke be sent down the kitchen sink drain? Plumber said a camera is usually too large to go down an inside drain. What other ways can we tell where they might be coming from? They are all over the walls in the family room but that’s where a lot of light comes in as well. Sorry this is so long but even the plumber was scratching his head, not good. The strip below is 2 weeks worth. Any advice would be welcomed!

 

[Reach4]

Nicely crafted post.

I would drape cheap (e.g. 0.7 mil) plastic drop cloths over everything to partition the kitchen+family area. If you have a washing machine, drape those. If you can divide a room temporarily, you could cut in half the possible locations. Maybe prop up some 2x2s or emt conduit or whatever, to hang the drop cloths from, or maybe even masking tape could hold up the plastic sheets.

I am wondering about a floor drain hiding under something like the washing machine.

Drape the kitchen sink, cabinets, and anything else you can isolate.

https://www.walmart.com/search/?query=plastic drop cloth

 

[Sponsor]

 

[James Henry]

https://www.orkin.com/flies/drain-fly
Their living in the slime in your kitchen sink drain, or you have a sagging pipe that is holding water. Don't call anymore plumbers, clean your pipes. clean your garbage disposal.
I had the same problem, they were showing up in my kitchen.

 

[Reach4]

In https://terrylove.com/forums/index.php?threads/in-praise-of-the-drain-fly.66239/ I presented a positive commentary on drain flies. However they need working drain traps to keep them confined.

 

[EdwardSoftly]

https://www.orkin.com/flies/drain-fly
Their living in the slime in your kitchen sink drain, or you have a sagging pipe that is holding water. Don't call anymore plumbers, clean your pipes. clean your garbage disposal.
I had the same problem, they were showing up in my kitchen.

Thanks James. We replaced the garbage disposal a couple years ago and we had the infestation way before that. We had a service totally clean all pipes ($700 worth) last fall but to no avail. I will post photos of our traps. A couple are admittedly S-traps which I know are now a no go but seem like with our drains the way they are, might have to be? Again, any advice on re-structuring any traps would be welcomed as well.

 

[EdwardSoftly]

Nicely crafted post.

I would drape cheap (e.g. 0.7 mil) plastic drop cloths over everything to partition the kitchen+family area. If you have a washing machine, drape those. If you can divide a room temporarily, you could cut in half the possible locations. Maybe prop up some 2x2s or emt conduit or whatever, to hang the drop cloths from, or maybe even masking tape could hold up the plastic sheets.

I am wondering about a floor drain hiding under something like the washing machine.

Drape the kitchen sink, cabinets, and anything else you can isolate.

https://www.walmart.com/search/?query=plastic drop cloth

Great advice. I appreciated it. I will try this. I also replied to James’ post with photos regarding our traps. That is the kitchen sink. I will post photos of the bathrooms below.

 

[EdwardSoftly]

Great advice. I appreciated it. I will try this. I also replied to James’ post with photos regarding our traps. That is the kitchen sink. I will post photos of the bathrooms below.

Here are photos of the access panel to the tub we put in back in 2010. They had to change something on the cast iron drain for the tub to fit. I’ve been told by a few pros that this isn’t where the problem originated but wanted to post photos in case they showed something of importance.

 

[James Henry]

For starters you need a new kitchen sink trap with an AAV. I'll let Reach explain it to you.

 

[Reach4]

The left kitchen sink trap is not vented. The problem is that the trap is an "s-traps" and the problem is that they can siphon empty if the flow is great enough.

The trap for the disposal may or may not be another s-trap -- depending on what is hidden by the disposal in that picture.

I doubt that is the cause of your drain fly issue, but it indicates that you may have other things wrong from that same time period where those were done. To fix it, there are methods that would involve one or two AAVs. For the interim, you can finish drain usage by running some water at a slow rate after using the drains for a big rate. You can also keep stoppers in those drains when not in use.

See #2 of https://terrylove.com/forums/index.php?threads/adding-ro-to-island-sink.83471/ as one right way.

 

[EdwardSoftly]

The left kitchen sink trap is not vented. The problem is that the trap is an "s-traps" and the problem is that they can siphon empty if the flow is great enough.

The trap for the disposal may or may not be another s-trap -- depending on what is hidden by the disposal in that picture.

I doubt that is the cause of your drain fly issue, but it indicates that you may have other things wrong from that same time period where those were done. To fix it, there are methods that would involve one or two AAVs. For the interim, you can finish drain usage by running some water at a slow rate after using the drains for a big rate. You can also keep stoppers in those drains when not in use.

See #2 of https://terrylove.com/forums/index.php?threads/adding-ro-to-island-sink.83471/ as one right way.

Thanks much. I will bring this to the attention of our plumbing guy. Still fighting the drain flies so I’ll keep an update to that. Seems they are coming through the walls or something, possibly behind the kitchen sink but who knows. It’s maddening

 

[JamiFids]

We have been dealing with a drain fly infestation for over 5 years now and we are beyond our wits. Quick background…..Our home was built in the 60’s, we are on a slab, ranch style. 2 bathrooms. We’ve had plumbers come and snake/clean drains. We’ve had plumbers just use smoke bombs on the roof in the 2 vents we have (one over bathroom/one over kitchen). The smoke did reveal a loose connection to bathroom drain (comes out of the floor) so that was re-done and is now nice and tight with no smoke. However, after the second smoke test to ensure a proper seal, no smoke came through but the strong silver smell just radiated in the back bedroom next to the bathroom. Plumber also saw no smoke in the attic so he was at a loss. We still suck up 50 drain flies a day and they just keep coming. They are in every room in the house but the majority are in the kitchen area/family room (one large room). No smoke came out of the kitchen drain or walls so we are left scratching our heads. We had to have a gas line that cracked replaced several years ago. We also have radiant heat under the slab and a line cracked several years ago that we had to have fixed. Tore up concrete to fix. So, my thought is the house has moved, cracking those other 2 areas, I’m sure there is a cracked pipe under the slab somewhere that is allowing these things to come up and go wherever they will. But the smoke revealed nothing. Can smoke be sent down the kitchen sink drain? Florida Environmental Pest Control said a camera is usually too large to go down an inside drain. What other ways can we tell where they might be coming from? They are all over the walls in the family room but that’s where a lot of light comes in as well. Sorry this is so long but even the plumber was scratching his head, not good. The strip below is 2 weeks worth. Any advice would be welcomed!

These are flies that live a few days, but manage to lay a lot of eggs. That's probably the problem. You need to call a pest control specialist to destroy both the flies and their eggs.