Narrative:

Approximately 1 hour after takeoff the flight attendants informed me that the water was indicating 3 gallons. We contacted dispatch to contact sfo ground to see if they indeed did fill the water system. From all accounts and after 4 hours we assumed that the system was full with 60 gallons of water. A phone patch with maintenance technician and dispatch was performed. Maintenance technician informed us that the B757 has been known to leak the water. That left an approximately 360 pounds of ice outside the aircraft attached to the fuselage. Maintenance technician informed us should it break off it would damage the flaps. Landing in a populated area might drop the 360 pound ice cube and endanger persons and or property. I decided to continue to mia and fly over the water some 20+ mi offshore until the ice had melted, then proceed to land at mia. We stayed at 10000 ft for approximately 80 mi at 29 degrees C temperature. Then got clearance to land at mia. Mia approach and ZMA were informed of our problem and gave us the clrncs we requested. After landing the suspect leak was placed in the log and maintenance notified. After some 8 hours after we left the sfo station still could not verify if the aircraft was ever filled with water. No procedure exists for this type of problem in any of our aircraft manuals. We landed with no incident or damage that we know of.

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Original NASA ASRS Text

Title: A B757-200 DIVERTED TO MIA DUE TO A SUSPECTED POTABLE WATER LEAK AND POSSIBLE ICE FORMATION ON THE POTABLE WATER SVC PANEL.

Narrative: APPROX 1 HR AFTER TKOF THE FLT ATTENDANTS INFORMED ME THAT THE WATER WAS INDICATING 3 GALLONS. WE CONTACTED DISPATCH TO CONTACT SFO GND TO SEE IF THEY INDEED DID FILL THE WATER SYS. FROM ALL ACCOUNTS AND AFTER 4 HRS WE ASSUMED THAT THE SYS WAS FULL WITH 60 GALLONS OF WATER. A PHONE PATCH WITH MAINT TECHNICIAN AND DISPATCH WAS PERFORMED. MAINT TECHNICIAN INFORMED US THAT THE B757 HAS BEEN KNOWN TO LEAK THE WATER. THAT LEFT AN APPROX 360 LBS OF ICE OUTSIDE THE ACFT ATTACHED TO THE FUSELAGE. MAINT TECHNICIAN INFORMED US SHOULD IT BREAK OFF IT WOULD DAMAGE THE FLAPS. LNDG IN A POPULATED AREA MIGHT DROP THE 360 LB ICE CUBE AND ENDANGER PERSONS AND OR PROPERTY. I DECIDED TO CONTINUE TO MIA AND FLY OVER THE WATER SOME 20+ MI OFFSHORE UNTIL THE ICE HAD MELTED, THEN PROCEED TO LAND AT MIA. WE STAYED AT 10000 FT FOR APPROX 80 MI AT 29 DEGS C TEMP. THEN GOT CLRNC TO LAND AT MIA. MIA APCH AND ZMA WERE INFORMED OF OUR PROB AND GAVE US THE CLRNCS WE REQUESTED. AFTER LNDG THE SUSPECT LEAK WAS PLACED IN THE LOG AND MAINT NOTIFIED. AFTER SOME 8 HRS AFTER WE LEFT THE SFO STATION STILL COULD NOT VERIFY IF THE ACFT WAS EVER FILLED WITH WATER. NO PROC EXISTS FOR THIS TYPE OF PROB IN ANY OF OUR ACFT MANUALS. WE LANDED WITH NO INCIDENT OR DAMAGE THAT WE KNOW OF.

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.