Black water tank 'inside' under the toilet

[TravelingTartar]

Has anyone ever tried, or what are the reasons for or against, building and placing a black water tank directly under the toilet but 'inside' the rig, above the floor? Basically, we would raise the toilet bowl up, say 18" above the floor and put the black water tank, obviously extremely well sealed, basically under. I find the space above the toilet is wasted and by putting the black water tank inside, we would have no freezing issues when we travel in winter in northern areas. All we would need is a simple step mechanism to step 'up' onto the now-raised toilet platform. I hope I've described this well enough to visualize it.

Thoughts? Laughter? Warnings of doom? Fire away ;-)

 

[CharlesinGA]

Dometic and Thetford both make shorty toilets for this purpose, and Escape trailers does just this, placing the black tank on top of the floor.

Charles

 

[Gary RV_Wizard]

No worries - do it. As Charles says, the shorty toilets are made with this sort of thing in mind. It's no worse than a cassette toilet used in many small campers. Remember the waste tank needs a vertical vent tube to the outside and a 3" discharge pipe. I've seen the vent run up a nearby corner and out through the roof.

 

[Ray-IN]

Very doable IMO. First thing is prior planning. Take careful measurements, create a drawing, re-measure. Placement might have an effect on weight distribution if the OEM tank is in a different location.
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[NY_Dutch]

If you have the room for a big enough tank to make it worthwhile, it could work. Our motorhome, as do many others, has a furnace vent that warms the waste tank area enough to keep it above freezing even at -4 deg.F, the coldest we've "tested" it.