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Where to store water tanks?

60920 Views 92 Replies 30 Participants Last post by  Jordan Y
I have seen fresh/gray water tanks online that are no more than 6 inches high. The best idea I have come up with is to insulate the floor, place the tank on top of that and then floor over that. This way in freezing temperatures the water tanks and plumbing lines would be safe as long as the interior was kept over freezing. This also does not use up valuable floor real-estate.

What have others done?
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My freshwater tank just arrived also... 25 Gallon 8x16x48" $140. Mine will go behind and partially over the rear wheel well about 8" off the floor (extended van). I haven't worked out the grey tank yet, but I plan to hang it below the driver's side slider.


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Yes, that makes sense, but in my application the gray water tank is mounted underneath the vehicle, and the bottom of the tank is just slightly above the level of the gas tank. Dropping the drain line to below the level of the gray water tank to create the trap would cause the plumbing to hang too low on the vehicle. We tend to drive on pretty rough roads where low hanging plumbing is not a good idea.
You should look into an inline trap.
I intend to install a 12v Water Solenoid Valve so I can drain the grey tank whenever needed. Like when that asshat is riding my ass ;)
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Inkog - what have you found for solenoids?
Here is a 1 1/2" NC for under $100.

I haven't decided on a grey tank yet, but it will more than likely be a repurposed fresh tank with a 1 1/4" opening. Those can be had for ~$60.
I think I looked into that solenoid, and it wasn’t rated for waste water. Particulates damage the valve.

Its a typical brass ball valve. I'd imagine you'd see years of service with a duty cycle of a few uses per week. Worst case scenario you'd have to put a cap on it until you can clean it up. The valve itself is serviceable.
The heating pad on the tank has a thermostat built-in. But the pipe tape for the P-trap‘s is a simple resistor. That’s the part that gets up to 150°. I looked around for other 12 V heat tapes, and I could find none that were capped lower than 150°. What brand are you using?

You could use a simple PWM circuit to help regulate those heat tapes. A 12v PWM LED dimmer rated for the amps should work a treat.
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Which valve are you planning on using? I was going to use a standard Rainbird but they are 24V. Does anyone know if 12V will open them? Guess I could always try...
Lots of 12v NC on amazon for reasonable prices. I have no experience with them as to how they'll hold up with sediment as @DaveInSeattle pointed out, but I'd imagine they'll work just fine in this application. They are cheap and easily replaceable anyway.
As I play around with layouts for various components in a high top extended Transit I keep wondering about how to divide the heavy items in the build so you don't get too much weight on one side. Some VW Westfalias have a distinct lean to the drivers side because of the kitchen, and propane and water tanks -- all located on that side. Does it matter that much with these heavy duty haulers?

My initial plan was to keep wet bath, fresh water tank (inside), gray water tank (outside), kitchen sink all on drivers side to avoid crossing the van width with any plumbing. I want to keep all fresh water lines inside van to prevent freezing. I would try to locate batteries, inverters, stove, fridge, furnace, and VW-style propane tank on the passenger side to partially balance the weight of the water tank. That would mean crossing the propane lines under the van for the hot water heater.

If I moved the sink to the passenger side to be near the stove, would it be possible to route the gray water to a tank under the driver's side? Do others situate their components for routing plumbing or propane or just put stuff where they want it and figure out the routing?
I made raceways under the raised floor to get hot & cold water and electrical to the other side of the van. They are insulated from the metal floor with 3/4" polyiso. I'm routing the passenger side galley sink drain back to a driver's side grey tank under the van.
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