Alan Trick
Are you referring to the waterway, or to the road? It doesn't make sense for the waterway to have access=private, unless you mean that boats shouldn't be on it, but I doubt anyone would be trying to go down a 6 meter waterfall. It doesn't look like the road is private. If you mean that falls are on private property, and people walk from the road to the falls, then you first have to add the path that they walk, and then tag the path with access=private.