Permanent Solution for Drain Flies, possible traps.

[LookingforSolutions]

Every year I encounter bouts with Sewer Flies. The problem originates at the Septic Tank which is a perfect breeding ground for them. Had it fully inspected by 2 separate companies and both said the tanks themselves are good. Honestly, in South Florida, no matter what I do, they'll find a way into my septic. Had it pumped, thoroughly cleaned, and cement sealed the lids. These things can make it through anything, maybe the drainfields, who knows... Anyways, I recently had my entire plumbing system smoke tested and fixed a loose vent stack pipe in the attic and some toilets. The system is now secure (one would hope). Regardless, I know they're still crawling my pipes just waiting to pounce on any weakness.

In looking for a permanent solution, I came up with this plan...

Put a mainline trap next to the cleanout outside and then a mushroom vent between the septic and mainline p trap. House has 2 vent stacks on the roof as well, but the mushroom vent will be needed for the septic if a trap would be placed between the vent stacks and septic. If the cleanout was right next to it, I figure any clogs would be easy to deal with.

I'm asking from a pure plumbing standpoint, is this something that could work?

Here is a diagram:

Any advice would be greatly appreciated!

 

[LookingforSolutions]

Anyone? Have a master plumber who says this should work. Pipes are PVC as an FYI.

 

[Sponsor]

 

[Breplum]

From someone who has never been near septic tanks or leach fields (metropolitan plumbing only), I don't know what a in-line trap does.
If every fixture is trapped and wet, then if flies get through those, why wouldn't they get through your new house in-line trap.
We do get some tiny sewer flies even here in the cities.

 

[LookingforSolutions]

Thanks for the reply, it is much appreciated!

To clarify, last year and this year they weren’t getting in past the traps. Last year was a hairline crack in a toilet flange. This year was a very slightly loose vent pipe in the attic (wasn’t loose last year, we smoke tested both times). After the issue was solved last year, they had already started breeding in a fridge drain pan, so I still had to find another breeding ground after we thought the issue was solved.

Collectively, I have spent 3 months dealing with these things in the last 14 months, killed over 1k myself and trapped on a glue board another 2k or so. My drain pipes have been hydrojetted too, so I’m pretty confident there aren’t many breeding grounds in the actual pipes. I do know for a fact they consistently find their way into the septic, so I’d like to keep them there when they do find their way in. My guess is it is drainflied related, but I can’t say for sure. The septic system has been thoroughly inspected and is in good standing.

I’ve read countless articles about these main line traps and how houses used to be plumbed with them many years ago (and a lot still have them from being built a long time ago). I know it isn’t ideal, but nonetheless, I believe it should work. The biggest issues I’ve read about are corrosion (cast iron) which has led to failure, and clogging. If my pipes are PVC and I have a clean out right there that I can easily access, I believe that should handle those. Along with a charcoal vent on the septic side, I believe it’ll be covering all of the plumbing logistics. That’s really what I’m trying to figure out.

I have no issue opening the clean out once a week for 3 minutes to make sure it’s flowing smoothly. That would equal 2.5 hours a year which is nothing versus the 3 months in the last 14 I’ve had to deal with this. This is why I’m looking for a permanent solution.

 

[Jeff H Young]

Looks ok . I dont know if it passes code probebly not. The vent a charcoal vent never seen and dosent that need 8 ft or so high?

 

[LookingforSolutions]

I’m not positive of the codes, tbh. I’m aware it isn’t ideal, but to me, my sanity, etc. it’s the lesser of two not ideal options.

I’m just curious if anyone sees any issues from a pure plumbing standpoint.

 

[Tuttles Revenge]

Whole house traps are a thing. Apparently still required in some NY jurisdictions. I don't even know if it needs a vent to function.

We see charcoal filters on the vents of homes near the waterfront in Seattle.. apparently fancy peoples shit does stink.

This summer a opossum died in my girlfriends old unused downspout drain.. about 2-3ft down. Massive amount of flies. I couldn't get it out as it was a goopy mess. So I screened off the opening in hopes of trapping the flies down there til they died. Yep... that worked, but they found their way into the basement somewhere! She had one of those bug zapping tennis rackets that I went to town on thousands of flies over the course of 2-3 days.. then nothing. The skeletal remains are still down there looking up at me.

 

[John Gayewski]

If each fixture is trapped then why do we care if there are flies in your septic tank? I'm not sure the problem here. Is it that they are getting into the house through the traps (which you said they weren't)? If they aren't getting thru the traps then how can they get into the house? Unless there's a problem that actually needs fixed such as a trap that siphons or a wax ring leak then I don't see the point in a house trap.

 

[LookingforSolutions]

Each fixture is trapped. I mentioned in the OP, this was an issue last year that took a while to solve, same again this year. Once they get in, it turns into a nightmare. The next time I have an issue, I’d rather not have to worry about these annoying flies.

 

[Fitter30]

Don't think there is a one and done solution. They live off the slime in the pipe and lay their eggs in it. I've used this dyi company before for different problems and had good luck with their suggestions.

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