We boondock a lot, and occasionally run out of fresh water in the tank. I don't always want to break camp and drive to a hydrant, so I bought 2 collapsible 5 gallon water carriers. Now, 4 trips to the hydrant will completely fill my 40 gallon tank.
HOWEVER, holding a 40 pound 5 gallon jug of water high enough to pour it into my tank is tough. I came up with a solution.
My rig came with a Shurflo 2.8 GPM pump #2088-422-144 (OEM version). I bought a Shurflo 2.8 GPM pump #2088-422-444 (after market version, but identical). I now have a drop in replacement spare pump, in case mine fails. I also put long hoses on it and a plug that plugs into a 12v connector I have near the water port. I put the hose on the input side into the 5 gallon water jug, the hose on the output side into the water inlet, and plug it in. No more lifting the water jugs.
EDITED TO ADD PICTURE OF PUMP:
Bobbo and Lin
2017 F-150 XLT 4x4 SuperCab w/Max Tow Package 3.5l EcoBoost V6
2017 Airstream Flying Cloud 23FB