small flies coming up through the sewer tanks

[tck]

Can anyone tell me how to rid myself of these midget flies.  They seem to be coming through the toilets or holding tanks.  The tanks are closed and have water and the tsp stuff in them.  I have recently flushed the tanks and cleaned them.  I do this on a weekly basis while in the coach.  I sure hope that someone will have a remedy for this.
Thanks.
TCK

[Pat723]

tck

The best way I know how to get rid of the flies is to.

1 Rinse the tank out with tank rinser on the outside of your unit, or if the stool does not have a trap in it try and rinse with pressure water the tank walls from inside the stool,    don't forget the rubber gloves. And then drain the tank.

2  Then fill the tank with water and use 1/2 gal of bleach let sit for a day or so if you can.

What the problem is that your sewer tank is not getting all the way clean.
Also when I travel, I dump before leaving if possible and put some water in it to splash around to clean the walls of the tank while driving down the road

Pat

[Ron]

Never Never use bleach in the BWT.   If we had such a problem we would add regular Dawn dish soap, Fill the tank, add Roebic K-67 and let it set at least 24 hrs then drain.

[Pat723]

Ron

Why not bleach

Pat

[BernieD]

Why not bleach

Pat

The bleach kills the enzymes that are part of the septic process in the holding tanks.

[Pat723]

BernieD

I understand what you are saying.
But it is a holding tank not a septic tank.
Not trying to cause a argument here, so do not take it personal just my thoughts

Pat

[Mick & Pat]

Are you sure these black flies are entering your RV via the black tank?

A few days ago we kept getting small black flies in our shower cubical so I place a rubber plug over the drain when the shower wasn't being used and the flies stopped.

I'm presuming that they are entering via the 3" sewer pipe which because of no U bent is open to the elements

[Ned]

The flies are very likely coming from the campground septic system, not from your holding tank.  Arrange your sewer hose so it has a loop in it, like a P trap, that will stay filled with liquid and that will keep the flies from getting into the holding tank.

And yes, it's a holding tank but there still is a bacterial action taking place that breaks down the solids.  That's why you don't keep the drain valve open on the black water tank, to let the bacterial action do its work.

[Ron]

Bernie and Ned are correct.  Kill off the natural bacteria and you will have serious odor problems.  Let nature do its job and all will be well.  When you hook up to sewer make a trap to keep the bugs from flying up into your grey water tank.

[BernieD]

Not trying to cause a argument here, so do not take it personal just my thoughts

Pat

No argument, nothing personal. Just the facts

[Chet18013]

Sewer flies are common in quite a few municipal systems. Some septic systems will have them also. The most obvious way into your tanks is via your dump hose. If you wish to get rid of them, just make sure you flush your tanks good and NEVER leave your sewer hose connected. I have seen many RVers who feel the first thing they must do upon arriving at a camp ground is hookup and open their gray--and occasionally black water valves. This just invites an invasion of the sewer flies, if they are in the system. More than once, I have been getting ready to dump, taken the cap off of the camp ground dump and seen it covered with sewer flies on the underside.

The only time my dump hose is connected to a campground site hookup is when I dump.

If you are there for an extended stay, Ned's suggestion of a loop in the pipe is good insurance.

Chet18013

[chick a dee]

tck:

Had same small fly problem you described. Flies would come out of the stool drain as it flushed. These were VERY tiny and just a bit bigger in appearance than fruit flies.  ANYWAY....after trying ALL solutions mentioned here, with NO success, we finally ended up buying a simple spray can of Raid brand "Flying Insect " killer, and...after dumping black tank, and flushing as usual, and after adding our usual amount of water to the tank (4-5 gal.), I then opened the flush gate between toilet bowl and drain down to tank, and holding the spary/fogger can close to the inlet into the drain I sprayed (fogged) 3-4 times down the drain at about 2-3 seconds each time, then closed the gate. To preclude possibility that the fog/spray might damage the gate and/or drain seals or plastic, I then flushed the toilet through it's usual three flush cycles, and......WE HAVEN'T HAD A FLY SINCE!!!  It's been about a month now, so it seems to have made a BIG difference.  Steve & Lynette

[tck]

Thanks to all for your suggestions.  Will probably try them all and after a full dosing they will be gone.