Three gallons sounds trivial until you need exactly three gallons in a space the size of a shoebox. The Ronco Plastics B377 measures 18.5 x 9.5 x 6.75 inches and exists for galley sinks, wash-down reservoirs, small camper conversions, and equipment sumps. It is a true B-series dual-role shell: with potable fittings the food-grade polyethylene holds drinking water, and with waste fittings it collects gray water from a single fixture.
Everything about it is manageable: 9 lb empty, about 25 lb full at 8.34 lb per gallon. One person installs it in minutes once the fittings are right.
And the fittings will be right, because they are installed per order. Print the drawing below, mark where the tank connects to your plumbing, and the factory spin-welds or threads fittings to those marks; the fitting planner on this page captures the details. Small tank, same Tustin, California craftsmanship Ronco has practiced since 1974.
More compact options under RV holding tanks and boat tanks. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B377 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.
