How would you interpret a colour tag on an underground hydrant? Is it the colour of the manhole, the device itself, the sign? Something else?
I just noticed that one of the online editors still asks the colour if the hydrant is underground and checked overpass turbo as that seemed odd to me as you generally can’t actually see them. To my surprise there are apparently 16588 examples in the database.
In the UK hydrant signs are yellow and around here at least the covers are usually painted yellow.
I’ve seen a mixture of painted and unpainted ones in Gloucestershire, I think they’re only really painting them as and when. The manhole and sign colours seem like they should be different tags to me as they aren’t the hydrant themselves, but I don’t know how this is actually being interpreted by other mappers.