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Old 10-26-2012, 03:56 PM   #1
4 Rivet Member
2007 27' Classic FB
Ridgefield , Washington
Join Date: Jul 2010
Posts: 493
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Optimal position for black and gray tank when dumping

I was surprised when hooking up not long ago that there was quite a bit of sewage left in my black tank from the previous trip. I normally wouldn't have discovered this because I don't dump the tank unless the trip is over or I'm 3/4 full.
My question is..Is there an optimal position for the trailer to be in when dumping the tanks? ie nose up/down. curbside high/low.

Thanks in advance.

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Old 10-26-2012, 06:49 PM   #2
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2018 Interstate Grand Tour Ext
Austin (Hays County) , Texas
Join Date: Jun 2002
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Tyhe outlet from both tanks are together, between the tanks. The trailer should be level to best drain both tanks.

Make sure there is plenty of water in the black tank before draining. I usually stand on the pedal for a while after the last use of the head.

If you have a flush, use it. I start flushing before hooking up the truck and just let it flush for 10 minutes or so. My tank is clean enough afterwards that I can see the white plastic of the tank bottom.

John W. Irwin
2018 Interstate GT, "Sabre-Dog V"
WBCCI #9632
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Old 10-26-2012, 08:23 PM   #3
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2008 27' Classic FB
Burkburnett , Texas
Join Date: Jul 2010
Posts: 974
If you think about the layout of your 27FB, the solids enter the tank on the curbside and the dump valve is on the street side. As Pahaska says, plenty of water is the key. This is what works for me: If we are going to use the trailer for 4-5 days, I run the tank flusher with the dump valve closed (don't get distracted) to put enough water in the BW tank before we head out. The trip home allows the mix to slosh and blend. When I get home, I dump with the flusher running and then close the dump valve for 5-10 minutes to put a significant amount of water back in the tank and then dump again. The last of what drains out is clear. Then I dump the GW to rinse the slinky.
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