Seven and three-quarter inches of height. That is the B211's entire vertical demand, and it is the reason this 18 gallon molding fits where tanks are not supposed to fit: under cockpit soles, beneath RV floors with almost no belly clearance, in the pancake-flat voids over a keel. The full envelope is 25 x 25 x 7.75 inches - a wide, square tile of a tank that hides in plain sight.
Ronco lists it for marine and RV service as water or waste, and the fitting order decides which. As a fresh tank the FDA-compliant polyethylene is potable-rated; as a holding tank the same seamless shell takes gray or black duty. Either way it arrives blank and never pre-plumbed: print the drawing below, mark the penetrations your system needs, and the shop spin-welds or thread-installs each fitting to your marks - or click them into place on the on-page fitting planner. Shallow tanks reward care here, since a pickup or dump even slightly off the low corner strands water you cannot afford to strand.
It ships at 24 lb and holds about 150 lb full at 8.34 lb per gallon, spread across a 25 x 25 inch footprint that is naturally kind to thin floors. Rotomolded in Tustin, California by the shop that has been drawing tanks around awkward spaces since 1974.
See other low-profile shapes in the boat tank category and RV holding tanks, or scan the full catalog on the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B211 dimensional drawing - print it to plan your install and mark exactly where you want fittings located; Ronco installs spin-weld or threaded fittings to your marked spec.
