The B189 is one molding with two careers. Ronco lists it as a 30 gallon marine water or waste holding tank, and the "or" is literal: the blank shell leaves Tustin with no fittings at all, and what you have it become is decided by the fitting order you place. Spin-weld a fill, a vent, and a pickup and it is a fresh water tank in FDA-grade polyethylene; order a waste inlet and a dump outlet instead and the same shell runs gray or black water below the sole. It is never plumbed for you - it arrives ready for the system you design around it.
Thirty gallons is a serious figure on a boat. As fresh supply it is roughly a week of careful cruising for two people; as a holding tank it is the difference between watching the gauge and forgetting it exists. Full of water the tank carries about 250 lb (water runs 8.34 lb per gallon), so mount it low and strapped to structure, and remember that whichever role you choose, the load is the same.
To order it, print the drawing below, mark where each fitting should land, and Ronco installs them to your marks - spin-welded or threaded - before the tank ships at 81 lb. The on-page fitting planner lets you drop the locations by click if you would rather not mail a sketch. Ronco has been rotomolding marine tanks in Tustin, California since 1974, and this dual-role approach is exactly why boatbuilders keep the catalog on the shelf.
See the whole marine line in our boat tank category, or every shape the shop molds on the Ronco Plastics hub. If it is headed for a coach instead of a hull, the RV holding tank and RV water tank ranges use the same construction. OneSource Plastics is an authorized Ronco Plastics dealer.
Technical drawing: download the Ronco Plastics B189 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.
