# Drain Flies



## robertc65 (Apr 16, 2005)

I have noticed now two Summers in a row once small flies begin to appear in our kitchen around the sink area but mostly in the basement. We only see one here and there so I never really thought much of it. This year I have began to notice more of them so I decided to try and figure out what kind of flies they are, and why they want to live in my house. I concluded that the flies are phorid flies or also called drain flies. I have not actually found where they are breeding, but I have noticed that I see more of them dead on the basement bathroom floor than anywhere else. The bathroom has a shower that is never used and has nasty water / sludge sitting in the drain. I plan to clean this out in the next day or so, but once it's clean is there a proper way to a cap this drain off since we don't use it? Can I also somehow push the water past the trap so it does not sit in there or is this a bad idea? I would not keep the drain un capped without water in the trap. I also have some concerns about the toilet, but I'll make that a separate thread. 

Thanks in advance

Rob


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## thom (Nov 3, 2006)

You can push the "nasty" water past the trap by pouring a bucket of clean water in, or just run the shower water for a few minutes. Unused traps should be flushed occasionally to counteract their tendency to dry out. The nasty water is probably from someone dumping a bucket of wash water down the drain and not flushing with clean water. You could pick up a wing-nut type of rubber expansion plug for the drain to seal it off.


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## robertc65 (Apr 16, 2005)

thom said:


> You can push the "nasty" water past the trap by pouring a bucket of clean water in, or just run the shower water for a few minutes. Unused traps should be flushed occasionally to counteract their tendency to dry out. The nasty water is probably from someone dumping a bucket of wash water down the drain and not flushing with clean water. You could pick up a wing-nut type of rubber expansion plug for the drain to seal it off.


Thanks for the response. So it sounds like you are saying that water should stay in the trap even though I have it plugged. Am I correct?

Thanks

Rob


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## thom (Nov 3, 2006)

Yeah, but...

The purpose of water in the trap is to create a seal so sewer gas cannot enter the building. When the water evaporates from a trap sewer gas has a nice open pipeline into the building. Plugging the drain will accomplish the same thing as water in the trap.


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## robertc65 (Apr 16, 2005)

So if I plan to plug the hole, is it better to leave the water in the trap or blow it out? I just thought the water would get kind of nasty in there after a while even if I had it plugged. 

Rob


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## thom (Nov 3, 2006)

If you plug the hole it doesn't matter. As for whether or not the water will get nasty, why is that even an issue? The sewer is nasty. If there isn't water there the sewer is still there.


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## robertc65 (Apr 16, 2005)

thom said:


> If you plug the hole it doesn't matter. As for whether or not the water will get nasty, why is that even an issue? The sewer is nasty. If there isn't water there the sewer is still there.


Good point.


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