My wife and I are currently living in my Keystone Outback in central Florida awaiting our house to be completed. We are living in it full time. I travel for work, so when I am gone I leave the front (shower) and rear kitchen) grey water tanks valves open. the black water tank is closed, as she will not even hit 2/3 of a tank in the week. I dump and flush them on the weekend I am at home. We use orange black tank enzyme packs. My wife is advising there are gnats that live in the black tank, and sometimes fly out of the tube going to the black tank when she flushes the toilet. She does hold the pedal down for a bit to ensure enough water to keep the poop pyramid problem from happening.I have not seen the bugs yet, but am wondering if she could add some sort of insecticide to kill any insect life in the black tank: but not turn the tank into a bomb or damage it.The upper ball seal in our Domatec 310 is leaking a little and the bowl will dry out over night. I plan on replacing the seal this weekend.I do have a "dip" in my dump hose that holds water to make a P trap for the shower grey tank and kitchen to keep sewer gas at bay from the park sewer line.Has anybody addressed this issue? Thanks for any assistance.

Google 'drain flies' for lots of suggestions. In the interim, I would fill the toilet bowl about half full before flushing to limit the time the valve is open.You may not have to replace that seal. The last time this happened to me, I opted to replace also but could have gotten by with brushing the old, dried out plumber's grease from the original seal, applying new grease and reassembling.

Fill the black tank completely...completely...with chemicals, shake it up by driving and drain..twice...three times is better.

I have not had this issue on a camper. But yea, there sewer flys. Caused by having an open sewer drain. So, in a normal home, there would be an open drain or no water in a trap for that to happen. I would rethink leaving the drains open or make sure there was a water trap.

Not sure how much but I would close the drain and pour some bleach down the toilet for overnight.Maybe a whole gallon but I am crazy like that. Rinse well the next day. Only open the drain every few days as needed.Good luck

I've seen people take their sewer hose that goes from the RV tank dump to the sewer line connection at the RV park and build a "p-trap" in it. THe will keep stuff from coming up the hose, but won't cure the problem of bugs currently living in the tank

Insect prevention in black tank | Good Sam Community

HappyKayakers
Explorer
May 22, 2021
Google 'drain flies' for lots of suggestions. In the interim, I would fill the toilet bowl about half full before flushing to limit the time the valve is open.

You may not have to replace that seal. The last time this happened to me, I opted to replace also but could have gotten by with brushing the old, dried out plumber's grease from the original seal, applying new grease and reassembling.
Lwiddis
Explorer II
May 22, 2021
Fill the black tank completely...completely...with chemicals, shake it up by driving and drain..twice...three times is better.
Sjm9911
Explorer
May 22, 2021
I have not had this issue on a camper. But yea, there sewer flys. Caused by having an open sewer drain. So, in a normal home, there would be an open drain or no water in a trap for that to happen. I would rethink leaving the drains open or make sure there was a water trap.
time2roll
Nomad
May 22, 2021
Not sure how much but I would close the drain and pour some bleach down the toilet for overnight.
Maybe a whole gallon but I am crazy like that. Rinse well the next day. Only open the drain every few days as needed.
Good luck
deltabravo
Nomad
May 22, 2021
I've seen people take their sewer hose that goes from the RV tank dump to the sewer line connection at the RV park and build a "p-trap" in it. THe will keep stuff from coming up the hose, but won't cure the problem of bugs currently living in the tank
mobeewan
Explorer
May 22, 2021
how to remove rv sewer flies & gnats
lane_hog
Explorer II
May 27, 2021
Sheesh, all these people dumping bleach and chemicals in the tanks... you do realize that all has to go to a water treatment plant eventually, right?

I've never used chemicals. Straight water has always done the trick for us. Never had sewer flies but we never leave valves open, not even the grey.
ronbiel
Explorer
Jun 10, 2021
You can use Pool Shock. Just be careful when using it because it can bleach almost anything.
mobeewan
Explorer
Jun 10, 2021
lane hog wrote:
Sheesh, all these people dumping bleach and chemicals in the tanks... you do realize that all has to go to a water treatment plant eventually, right?

I've never used chemicals. Straight water has always done the trick for us. Never had sewer flies but we never leave valves open, not even the grey.

So, instead of complaining about people using bleach and chemicals to kill bugs in their black tank do you have any constructive suggestions on how they get rid of them?
Grit_dog
Navigator
Jun 10, 2021
lane hog wrote:
Sheesh, all these people dumping bleach and chemicals in the tanks... you do realize that all has to go to a water treatment plant eventually, right?

I've never used chemicals. Straight water has always done the trick for us. Never had sewer flies but we never leave valves open, not even the grey.

Sheesh, what makes you think all the water goes into a sewer treatment plant, and if it does, what % do you think is actually from campers?
And what else do you think might be sent to sewer treatment plants?

Or in short, find something else to complain about that is actually an issue.

Oh, and OP leaves the black tank closed....according to him anyways, unless you know different.

And fwiw, we rarely used our truck camper, couple times a year, never left valves open, did get sewer flies on occasion, so, how is that explainable in your opinion?

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Insect prevention in black tank

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