A man was taken to hospital after staff in the cafe below his flat called the fire brigade because water was flooding from the ceiling.
Staff in La Dolce Vita, in Hatch End, noticed water coming down the windows at the front to the shop and knocked on the door of the flat above.
After not getting a reply they called the fire brigade, who gained entry to the property and found the man unconscious shortly before 4pm.
According to reports a broken sink was found in the flat.
Police and the London Ambulance service were also called to help the man, who was led out of the flat and taken to hospital by ambulance.