I live in a small part of a very large building (an old orphanage). Strangely, there are no downpipes from the gutters in the front of the 4-storey building. All the water is transferred to downpipes at the back of the building. Unfortunately the water goes over a valley in our part of the building. The quantity of water after a heavy rainfall is immense; it sounds as though a large river is running over one's head. There is occasionally a slight leak through the ceiling at one point.
I'd like to put up a downpipe in the front of the building. There is a place where this would not be obtrusive. I would collect the water in a tank below.
Unfortunately two builders I have consulted have given different opinions. One (a roofing expert) says that it is not possible to attach a downpipe to the gutters, because these are cast iron. The other expert says he can do it.
I wonder if anyone has a view on this?