They call it black, but its really blue...

The toilet waste water tank comes from Ardemco.  They have a variety of sizes and place the openings on a custom basis.  The design goal was to have the tank inside the heated space to eliminate freezing.  This meant building up the bathroom floor to accommodate the tank.  The B319 tank, at 4.75" high minimized the height of the raised floor, while still allowing an 11 gallon capacity.  The photo below shows a markup in the vehicle, with some rings showing the inlet and outlet locations.  The dimensional diagram shows the specifics.  Here is the document faxed to Ardemco for the order.  Ardemco is available on the web.

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The tank is installed on a bed of silicone caulk and blocked in by 4 x 4 blocks secured with large lag screws to the floor.

Insert Pic of installed tank