The B225 is a 22.5 x 22.5 inch square, 12 inches deep, holding 25 gallons - a footprint with no long axis, which is rarer and more useful than it sounds. Corner voids, square hatched compartments, and the boxy bays under RV dinettes all defeat rectangular tanks that insist on length; a true square drops in either way, in either orientation, and wastes nothing.
Ronco lists the molding for marine and RV duty as water or waste, and the blank shell commits to nothing until your fitting order arrives. Fresh service runs on FDA-compliant, potable-rated polyethylene; holding service uses the identical seamless rotomolded wall for gray or black water. It is never plumbed for you - print the drawing below and mark the penetrations your system needs, or set them on the on-page fitting planner, and the Tustin, California shop spin-welds or thread-installs each fitting to those marks, per-order, the way it has worked since 1974.
At 25 lb empty it is an easy solo install. Full, it puts about 208 lb (8.34 lb per gallon) on its 22.5 x 22.5 inch base - compact enough that the mounting surface should be solid material, not spanning sheathing. Strap into structure and leave the fittings serviceable.
For hulls, see the boat tank category; for coaches, RV water tanks and RV holding tanks; for the whole catalog, the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B225 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.
