Does anyone have any ideas about how to evaluate the difference between rising damp and a plumbing leak in the concrete floor of a ground floor flat? Any tips much appreciated.
mia

If it's something which has only recently happened, it's more than likely a plumbing leak.

It would also depend where it was in the room. Take some of the screed up, and see if it wet on top of the oversite. Try not to chop through any pipes.