I have a 40 gal Titan high polymer tank in the bed. It came with its own pump system and all I need to do is press a button in the cab. It will add into the truck tank 5 gal in a 10 min span and then shut off. I repeat if I want more. Of course I can shut it off before 10 min if I want. The in cab controller has 10 small LEDs, when lit, show how full the tank is - also making it easy to know how much I need to add when I refill it....should it not be empty.
It was really easy to change out the inline filter located above the tank, within a compartment. I also order a locking cap.
They make a 50 Gal version, but I wanted the extra space on the sidewalls (The 40 gal version is not as wide as the 50 gal.)
I love the extra capacity.