a Word of caution with yard hydrants. they can contaminate the water. When in the "off" position the drain cock let's the water from the stand pipe drain out. If your yard is with a bunch of clay soils, the hole stays filled with ground water. This means the stand pipe has some level of ground water in it. Once you turn on the water, drain is blocked and fresh water pushes up the nasty ground water.
Up to this point, you can just say, "don't drink the water until it runs a spell." But if by chance you had a hole connected and it was off, it could back siphon into your drinking water. Check valve solves this but no one does.