Holding Tank Pump Out and Flies

[asalotto]

Twice this past summer, I've emptied my holding tank, legally offshore of course, via my macerator. Both times I went from 0 to like 100 flies in minutes. At first I was amazed that the flies smelled this all the way from shore and came a calling. But then I wondered if they weren't in the tank to start, and came out the vent when the tank was emptied. Have others experienced this, and if so, what's the "fix"?

Thanks!

 

[sail sfbay]

Suggest a thorough flush at a pump out station. This article might be helpful: Get Rid of Drain Flies in Your RV | Flush Holding Tanks (goodbyedrainflies.com)

 

[Peggie Hall HeadMistress]

I read that article and found it interesting. lthough "sewer flies" are common in RVs, they're pretty rare in marine sanitation systems. In the past there have been tank products and at least one treatment device that used maggots to liquify waste..the maggots were sold commercially, flushed down the toilet. You knew it was time to replace the maggots when flies starting coming out of the bowl.

While rare, any sewer flies aboard boats today are common enough to support my advice that holding tanks should be thoroughly flushed out 2-3 x season and especially in preparation for any extended layup. I would not use bleach or any other household chemical and I would eliminate any p-traps in sanitation or gray water (sink or shower drains)...they have no place on a boat anyway.

--Peggie

 

[DArcy]

You knew it was time to replace the maggots when flies starting coming out of the bowl.

I'm just picturing them coming out of the bowl while it was in use. That would be an interesting experience

 

[Terry Cox]

Have others experienced this, and if so, what's the "fix"?

No, never. I do make it a practice to always pump out the holding tank after each cruise. That means flushing the tank until discharging clear water. That should leave no residue for critters to gather and grow.