That's interesting. So stainless steel custom build? Condensation may be an issue in a trapped space. Is the tank going to carry the floor load, or will there be a beam supported floor above it?


I hung a 20 gallon plastic tank under the bed platform, above the wheel well.

 

No, plenty of composites on the amazons. They seem plenty sturdy to carry a medium load, whatever that is.

 

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These are standard RV water tanks that never have any downward pressure from the top. RV floors are typically a sandwich construction with internal ribs (or "joists") of 1-1/2" aluminum square tube. That floor sits on top of the c-channel frame grid. The water tanks hang from that same c-channel frame. There is never any downward pressure on the tanks from the floor.

Not saying you couldn't find tanks with some internal structure that allows them to bear weight, but I don't think that would be common. If you don't plan on putting much weight on your garage floor then you might get away with putting plywood and maybe some insulation on top of the tank.

 

Interesting idea. 4 1/2" is a lot of headroom to give up, plus you'd need at least another inch of structure above it, but I guess if it's under your bed it won't matter as much.

 

I can see that if the van is not leveled or tilted towards the outlet, you will have a problem with running out of water.

 

No experience... but wouldn't putting the tanks underneath the van make more sense? You can get up to 25 gallons cheap and easy on the driver's side and ~15 gallons on the passenger side (but more expensive).

 

Wheel well tanks work well and you can drain most of the water. I think it would be difficult to drain most of the water out of a flat tank if the van is sitting at an unfavorable angle.