[Chester Stone]

I am in a California RV park for several weeks and I tried to connect to the parks water supply. My plan was to use the city water pressure and supply, close the valve closest to the tank to accumulate black water, and drain the grey water continuously. The tank filled but the auto shut off valve did not stop the water from overflowing the tank. If the auto shut off valve works properly when the tank is full, how do I take advantage of the cities water pressure without having to use my pump? Am I using an incorrect procedure to connect to the city water supply?