Most truck stops have water. I've filled my tank at FlyingJs.
You can also get water at many municpal water plants during normal business hours.
If in doubt you can chlorinate according to your motorhome manuals or search the internet for the correct amount of chlorine add.
You can also stay at a campground every week to 10 days and dump your tanks and fill up with water.
Another thought, if you belong to FMCA, is to pull out your member directory or search the members online and contact a member in the area and ask about filling you tank. There is a lisitng of "Stop Over Spots" and "Come Visit" offers whom I'm certain would let you take on water.
Sarver, PA/Crystal River, FL/Shelocta, PA · FMCA 335149 · W3TLN
2005 Suncruiser 38R · W24, no chassis mods needed · 2013 Honda Accord EX-L · 2008 Honda Odyssey EX-L