The B413 is a 28 gallon example of the idea that runs through Ronco's whole marine B-series: one rotomolded polyethylene shell that becomes either a fresh water tank or a gray/black waste holding tank depending on the fittings you have installed. The molding itself does not care which job it gets - the plumbing decides. Order it for potable service and it goes in with drinking-water-appropriate fittings; order it for the waste side and it becomes the holding tank instead.
Because it ships as a blank, the layout is yours. Print the technical drawing below, mark where your inlet, outlet, and vent need to land, and Ronco spin-welds or thread-installs the fittings to those marks before the tank leaves the shop. The on-page fitting planner walks you through the choices if you have never specified a tank this way.
Plan the structure around the filled weight, not the shipping weight: the blank arrives at 41 lb, but 28 gallons of water is about 234 lb sitting on your bilge stringers. Ronco has been rotomolding these in Tustin, California since 1974, and the same shop builds everything on our Ronco Plastics hub and in the boat tank category. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B413 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.
