Water Leak From City Water Connection

There is a brass backflow valve on the hot water heater that I had do the same thing to me after the city intake last year. Sucks- I learned how to repair it after reading a few pages, and you can still get the part for the hot water heater. Seems like the obvious stuff fails- when you winterize your unit they tell you to actually push on the valve so that you get the antifreeze to come out.