[As much as he is in fact standing next to a human-shaped pressure washer, pure water alone is probably not sufficient for this task.]

It seems to have been abandoned for many years - two centuries at least, if I were to guess. Though that's assuming that this current storm isn't a constant state - water damage would expedite the process.

[Though the construction is unfamiliar to him, he is old enough to have a sense of how old something is. And there is not a sense that this place has been disturbed in a long time - not only in physical traces, but in the feeling of the water itself.]