1974 safari water leak when hooked to town water

[Jasper_pilot]

I am new to the airsteram world as I just purchased this 1974 Safari last week, The trailer is in very good condition as it has been stored inside and never used for at least the past 10 years. Well now I have the job of getting everything back working again. I'm now working on the plumbing after getting all of the appliances working. I hooked the garden hose to the town water supply to find that the water drains out of the drain cock under the rear of the bumper. Both taps are shut off under the bathroom sink but it still continues to run. Is there a pressure relief valve in the rear of the trailer after the pressure regulator? Also how do you adjust the water pressure on the pressure regulator? I think that counterclock wise on the screw should lower the pressure is this correct.