_The filler opening at the truck end has to be higher than the tank_.
Assuming the delivery truck is sitting on the same level as the tank
and the tank will be at least 5 ft high, then a reasonable slope to the
pipe will put it at around 7ft over 20 or 30 ft run.


It is also helpful if the fill-spout is somewhere
where the truck driver doesn't have to climb
a ladder to get to it. 7' up seems excessive.