Harbor Freight has a cheap marine water pump that runs off of 12 volts DC.
It pumps up to 260 gallons per hour and uses only 5 amps/hour DC which is not a whole bunch. has 35 foot head but I've never tested it as I need about 3.5 feet head.
Its too much work to take the 7 gallon water containers out of my tall truck bed so I leave them in there and run about 30 feet of hose (5 foot section for pickup, and 25 feet output hose) Works perfectly.
12 Volt Marine Utility Water Pump
I have one and am very happy using it to pump water from 7 gallon jugs into my fresh water tank.
Several Power Source options to consider:
Portable rechargeable auto jump starter works just fine in a pinch.
Plug into tow vehicle tow plug
My generator has 8 amp/hour DC output
Plug into tow plug on back of my 5th wheel
Hardwire a convenient DC connection.
Before getting the pump, I was drawing water from my 7 gallon containers via the RV pump using the bypass that is normally for winterizing/antifreeze. I prefer filling the fresh water tank.