1. Hey I’m glad I came across your page on this matter. My husband children and I travel for his work and we spend quite a bit of time in our Rv. We learned YEARS ago to keep the black value closed unless we are flushing it. However, we still have this issue with these pesky & disgusting fly/gnat creatures. We don’t keep the gray value closed though, could this be part of our problem?? I’m thinking about closing it and seeing how that goes.
    We’ve tried bleach in the past but have been weary of using it again as it can be damaging to parts of the system. I’m thinking that maybe another round of bleach may be necessary, heck it’s worth a shot.
    What are your thoughts on the Rv fruit fly products meant to be put in the drains ? Have you heard of any success there??
    I’m desperate…. And ready to be rid of these suckers.
    I’ve also noticed that with winter weather this is a non-issue. They seem to like the warmer weather as far as I can tell.
    Thanks So much

  2. I think if you leave the gray closed your flies may clear up. Also they won’t have much opportunity to get into your RV if you are closed all the time. If you do bleach, you are only doing enough to kill the flies so your amount could be very, very minimal – more about flies breathing chlorine than cleaning the tank. But just try keeping everything closed all the time. We never tried the products as we were able to get them managed without.

  3. As a former USDA Food Safety Inspector I am all too familiar with the dreaded drain gnat. Bleaching the drains are the only thing that will kill them. Here is my battle plan:

    1. Put 2 capfuls of bleach in every sink full of dishes you wash.
    2. Do NOT put any food residue down the drain…this includes milk from cereal!
    3. Make sure your sewer securely attaches. Any gaps will allow flies to invade and procreate.
    4. Repeat Daily

    Because we are full time in our motor home, I check everyone’s connection. Your neighbors drain knats are yours as well. Hubby bought a hose contraption that cleans out your tanks. Hoping this will just add another layer to my battle plan!


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