We have almost all ours inside, but they are against an outside wall, so they are easy to get to, just reach under the wall with the back hoe.  In fact, we just replaced on this summer, so I know it's easy.

We really prefer to have the hydrants inside, but that may be a sheep thing.  I very seldom need a hydrant for a cow unless I have one penned up during calving.  Cattle mostly drink out of outside fountains.