When Traveling, have ya found yourself without water, but near a Commercial building with that "Garden" hose spigot that takes a "Special" Tamper proof handle.
Churches, Rest areas, baseball diamonds with, City county parks with out-buildings, Factory, doctors office, etc etc etc.
Get a 4-way Sillcock Key. (3inch X, pocket size) Just $6.-$9. Home depot. local hardware, etc, Just about anywhere that sells Plumbing tools. (There are the standard 2 size keys, But then you would need to carry both and more $$)
Some have a door covering the Valve, it Most often takes the same key.
Just be respectful, and don't waist, or make a mess.
And before the SELF-Righteous start in about, "STEALING", I can't imagine, anyone saying, NO you can't "take" a little water to drink.
If the building was open, they would most likely Tell you where INSIDE the building you can get water, & And in some areas It's a LAW, if you ask for water to drink, they must provide it.
The Tamper proof valves, are usually installed to prevent Kids, VANDALS, etc. from turning it on and LEAVING it on.
Travel Safe! Travel Well!