Small systems need tanks too: the Ronco RVB267 is a 3 gallon light-duty polyethylene fresh water tank shipping at just 7 pounds. It suits compact RV applications where a few gallons of potable supply is the whole requirement, and it is rotationally molded by Ronco Plastics in Tustin, California, molding poly since 1974.
Even at this size the material is FDA-compliant natural polyethylene, and the translucent wall shows the water level through the tank, no gauge needed on a tank you can hold in one hand.
Ronco treats the RVB267 like every tank it makes: spin-weld or threaded fittings installed per order at the locations you specify, with drawings, where shown, depicting the blank molding. OneSource Plastics is an authorized Ronco Plastics dealer.