If I am not mistaken a 17Z has pretty small tanks right, ~20 gallons? If so I imagine you are not looking water to shower; but mainly dishes, toilet and possibly drinking -- right? If so, and you can't find water conviently to fill up, maybe just by a few of the 2.5 gallon water jugs from a gocery store in town. They can usually be had for a ~$2 each and there is no concern about the quality of the water source.
Or even better, the grocery store where I live, allows you to fill 5 gallon water bottles for .25 gallon. You could just fill a couple of those and use your gravity fill to get it in the tanks.
If you had a JayFlight with the 80+ gallon holding tank that would be a challenge and expensive. But smaller tanks open more possibilities without breaking the bank.
2007 Chevy Duramax LMM/Allison
2012 Jay Flight 29QBH
2012 Jay Flight 26BH (Sold)