Most owners who buy the B423 are buying holding capacity, and 29 gallons is a genuinely useful black water number - enough that a family aboard for a long weekend is not rationing flushes or hunting a pump-out every second day. But nothing about the molding itself is waste-specific: it is a B-series dual-role shell, and ordered with potable fittings it serves just as happily as a 29 gallon fresh water tank.
The role gets locked in when the fittings go on. Ronco installs them per order - spin-welded or thread-mounted at the positions you mark - so the inlet lands under your head discharge and the pump-out lands where your deck fitting actually is, not where a generic mold guessed. Print the drawing below, mark it, and work through the on-page fitting planner.
This is a thick-walled shell for its size, shipping at 108 lb bare, and it carries about 242 lb of liquid when full. Molded in Tustin, California by Ronco, tank specialists since 1974. Dedicated waste-only shapes live in the holding tank category; the marine range is under boat tanks. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B423 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.
