IMHO = In my humble opinion
You can always try a church or a BPOE hall, county and city parks sometimes have spigots available. Sometimes Fast Food places will have a spigot outside (to wash their sidewalks) I have watered-up in someones front yard (small town, I asked and they said sure!!) Flying J gas stations always have water available.
Get yourself a Water Thief aka: Water Bandit too:
Camco Water BanditThe big thing to remember, when wanting to utilize any of the above mentioned ways, always ask politely first.
WoodGlue