If it came down to it, I wouldn`t hesitate to knock on a door or stop a passing vehicle for water (or for anything else), but I don`t want to plan for that. Besides my dislike for having to ask or beg favors, in my opinion it`s irresponsible to use those options as a "Plan A". Anybody is welcome to disagree, though.

A few comments in this thread note that there are not many stretches where you can`t get potable water for days at a time. That`s true, but if plumbing or bottled water aren`t available even for the better part of one day, and there`s a known river or lake, etc on that part of the route, I`d rather use treated water than carry it. Personally, I don`t mind iodine taste.