Filling water tank without pressurized hook up

We have an Open Range 5er and it has the same capability as others have noted. The pump will suck on about 2 to 3 gallons/minute. We carry 2 to 5 six gallon jerrycans when traveling. The number we carry is dependent on availability of water and hiw long we plan to boondock aka "dispersed camp".

But , as noted above, one is doubling pump usage.
Reed and Elaine