I've had water pour on my on a BA 747. Was quite a few years ago but it's caused by condensation which then finds a way out when the plane takes off and tilts upwards.
Yes it's condensation and happens on every airliner, but the water is normally contained by the thermal insulation and runs behinds the panels down to the bilge area (at the bottom of the fuselage barrel). Some issues in the insulation condition or installation can result in water dropping in the cabin.
Interesting, thanks! Did always wonder why sometimes you can hear some running water in the panels. I always assumed it was something on the outside of the plane.
This happened to me on an emirates A380, but on landing. The timing was comical because immediately after touching down (and being rained on) the entertainment screen prompts you to rate your flight.
On a flight from LAX to China, I saw condensation of nearly a gallon of water pour out of an overhead compartment and drench a row of seats. The flight was full, and the soaked people had to stay put.
