This Camco Rhino Portable Camper/RV Tote Tank can hold up to 28 gallons of waste. This portable holding tank has a 3-foot super heavy-duty sewer house and a built-in gate valve to empty it easily.

Gate Valves Camco Camper/RV Gate Valve with Built-in Clear Adapter | Features 3.5-Inch Long Clear Adapter, 4 Bayonet Prongs, and Fits 3-inch Sewer Fittings (39053) Camco ...