Soundguy - maybe I am wrong here. Originally you made it sound like you have in the past hooked up and stay hooked up to a community water spigot if it was nearby like right in front of your site. And if someone came along and needed to fill their tank or a bucket then you would disconnect and let them do that. That I think is totally wrong.
Now it almost sounds like you are saying that you just hook up to the spigot to fill your tank, but if someone needed a bucket of water than you let them fill it up instead of waiting for you to fill your tank. If thats what you do then fine and good job. I agree that if you are just using it to fill your on board tank and someone else comes along to fill theirs, then yes they need to wait until you are done since you were their first.