The B542 has a perfectly square 21.25 x 21.25 inch footprint, stands 13.5 inches, and holds 24 gallons. Square tanks are underrated: they fit hatches and lockers that were themselves framed square, they present the same face whichever way they drop in, and they leave no awkward sliver of compartment behind them.
As a marine B-series molding it is dual-role by design. Ordered with supply fittings it is a fresh water tank - the polyethylene carries FDA approval for potable service. Ordered with waste fittings, the identical blank becomes a gray or black holding tank. Ronco spin-welds or thread-installs the hardware at the positions you mark, which on a symmetric tank is a genuine freedom: any of the four sides can be the plumbing side. Print the drawing below, choose, and record the layout in the on-page fitting planner.
It ships at 25 lb and carries about 200 lb full - an easy structural load spread over a wide, even base. Molded in Tustin, California by Ronco, who have been shaping polyethylene tanks since 1974.
Square and near-square alternatives cluster in the boat tanks and RV holding tanks categories; the whole family is on the Ronco Plastics hub. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B542 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.
