Ronco Plastics 12H - 18 Gallon Recessed End Dump RV Holding Tank (No Rails) (22.0" x 23.0" x 12.5")

The 12H goes deep instead of wide: 18 gallons in a 22 x 23 x 12.5 inch cube, the deepest draw in its capacity class. A tank like this occupies a compact square of floor - barely two feet on a side - and pays for it in height, which makes it the natural pick for bays under dinette seats and in vertical chases where footprint is scarce but headroom is not.

Depth has a plumbing advantage waste tanks care about: a 12.5-inch liquid column drains harder and cleaner through the dump valve than the shallow puddle in a low-profile tank, carrying solids out with it. The blank ships at 18 lb; full, it holds about 150 lb of gray or black water concentrated on that small base, so the floor under it must be structural.

Two cube-family relatives bracket it: the 56H with 21 gallons at 22 x 22 x 12 inches and an end dump, and the 10H at 22 gallons and 34 x 22 x 12 inches when you can spare more length. The rest of the shapes are in the RV holding tanks category.

Strictly waste service - never fresh. One Source Plastics is an authorized Ronco Plastics dealer.

Fittings

This holding tank ships with its outlet molded in, ready to plumb. Add the Ronco 3-inch uniseal (F3UNISEAL), a loose pipe-to-tank seal you press into the outlet yourself, with no threads or nuts.

Technical drawing: download the Ronco Plastics 12H dimensional drawing - print it to plan your install. The outlet is molded in. Add the Ronco 3-inch uniseal to connect it.