Narrative:

Last 1 hour of flight, flight attendant advised water leak in main cabin between doors #2 and #3 in overhead panels. Water was shut off to all galleys. Water leak continued. About top of descent flight attendant reported electrical smell in cabin. All galleys were shut off (electrical power). Emergency was declared to get expedited approach to kix. Smell dissipated. Emergency was canceled with ATC. Landed without any problems. If crew had some way of shutting off supply of potable water at its source, the water leak probably would have stopped. I have been informed by maintenance that a drain mast circuit breaker had popped and that electrical power to heat waste water discharge did not work properly and that the water backed up into the aircraft.

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Original NASA ASRS Text

Title: A B747-400 AT TOP OF DSCNT DECLARED AN EMER DUE TO AN UNCTLED CABIN WATER LEAK CAUSED BY A FAILED DRAIN MAST HEATER.

Narrative: LAST 1 HR OF FLT, FLT ATTENDANT ADVISED WATER LEAK IN MAIN CABIN BTWN DOORS #2 AND #3 IN OVERHEAD PANELS. WATER WAS SHUT OFF TO ALL GALLEYS. WATER LEAK CONTINUED. ABOUT TOP OF DSCNT FLT ATTENDANT RPTED ELECTRICAL SMELL IN CABIN. ALL GALLEYS WERE SHUT OFF (ELECTRICAL PWR). EMER WAS DECLARED TO GET EXPEDITED APCH TO KIX. SMELL DISSIPATED. EMER WAS CANCELED WITH ATC. LANDED WITHOUT ANY PROBS. IF CREW HAD SOME WAY OF SHUTTING OFF SUPPLY OF POTABLE WATER AT ITS SOURCE, THE WATER LEAK PROBABLY WOULD HAVE STOPPED. I HAVE BEEN INFORMED BY MAINT THAT A DRAIN MAST CIRCUIT BREAKER HAD POPPED AND THAT ELECTRICAL PWR TO HEAT WASTE WATER DISCHARGE DID NOT WORK PROPERLY AND THAT THE WATER BACKED UP INTO THE ACFT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.