Six inches tall. That is the whole story of the B425: a 25 gallon capacity flattened into a 36 x 32 x 6 inch pancake that disappears under floors no other tank format can use. Underfloor voids in RVs, shallow sub-sole spaces in powerboats, platform beds in van conversions - spaces that are wide and long but have no height at all are exactly what this molding was tooled for.
It is a dual-role B-series shell, so those 25 gallons can be fresh water or gray/black waste; the fittings you order set the role. On a tank this flat, fitting placement is everything - there is no sump to gravity-drain toward unless you put the outlet where your floor actually slopes. Print the drawing below, mark your positions deliberately, and use the on-page fitting planner; Ronco spin-welds or thread-installs to whatever you mark.
The blank ships at a manageable 37 lb, while the water inside a full tank weighs about 208 lb spread across that broad footprint - support the whole panel. Molded in Tustin, California by Ronco, rotomolding tanks since 1974. Compare other shallow formats in the RV water tank category and the marine lineup. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B425 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.
