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Old 08-04-2019, 09:03 PM   #1
1 Rivet Member
Valrico , Florida
Join Date: Feb 2019
Posts: 8
Toilet not directly over black tank?

Looking to finally redo the resr bath on our 22 foot Argosy. I want to change the black tank to go under the floor rather than over it, but I was curious if anyone had installed a black tank offset from the toilet itself. Most posts that I see have the toilet directly over the black tank, but has anyone installed a toilet in a different location other than directly over the tank? If so, any special considerations that I should take?
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Old 08-04-2019, 09:27 PM   #2
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2012 25' FB Eddie Bauer
Vintage Kin Owner
Virginia Beach , Virginia
Join Date: Sep 2004
Posts: 7,304
The toilet is called "gravity flush" for a reason. Having the poo hit a moderately sloped pipe instead of the bottem of a tank ... well obviously, that is a cumulative problem from an engineering standpoint. If you engineered the bathroom sink waste to go into the black tanl at the.top of the toilet drain (like some 28 footers do) it would solve that problem, but then warm the contents?

Go bigger, go below the floor but obey gravity. It IS a law!
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Old 08-04-2019, 09:30 PM   #3
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1992 29' Excella
2010 22' Interstate
Van By The River , Georgia
Join Date: Feb 2002
Posts: 2,155
Some experts will likely provide more specific details but I'll tell you what I've learned from several people who work on trailers...

There is usually insufficient space under the floor to run any sort of sewer line from the toilet to a tank that is offset from the toilet. The sewer line needs to be several inches in diameter and needs to have appropriate pitch to drain from the toilet to the tank. In a home this means using over a gallon of water per flush to move the solids through the pipe. So a black water tank offset from the toilet has two main issues - insufficient space and uses too much water.

1) An option might be to consider a composting toilet. I know it sounds weird but those I've seen installed in RV's and used properly seem to work very well. 2) Another option is a macerator toilet - this allows a smaller pipe from the toilet to the black tank, allows for less pitch of the pipe but still uses much more water than a conventional RV toilet. 3) A friend of ours uses a cassette toilet in one of his vintage trailers. Initially I didn't like the idea but the great thing is he can "dump" the toilet in any rest area he chooses and doesn't need to find an RV dump station. May not be a bad choice.
Lucius and Danielle
1992 29' Excella Classic / 2010 Interstate
2005 Chevrolet Suburban K2500 8.1L
2018 GMC Sierra K1500 SLT, 6.2L, Max Trailering
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