Control city water supply with 12v water valve

Those diaphragm valves often times are used with big irrigation pumps, way more pressure than you'll typically see in a residential or even campground setting.

Good point on the sun affecting the feeder hose.... why not just screw the electric valve straight onto the water hydrant? Probably good to protect the valve body from the sun also, since they're designed to live in a basement or be buried underground out of the sun.