I have read of similar situations on the forums in the past. My city water and black tank flush connections are in a locking compartment. I use a typical water hose shut off valve on both. The one on the black tank allows me to turn the water on and off while flushing the tank without having to go to the main water spigot. When we leave for any period of time, I turn off the water valve in the compartment. That way in the event anyone was to mess with the water spigot it does not put the RV at risk of flooding due to the original posters situation.