Narrative:

Prior to getting to the airport; I received a call from the chief pilot and the duty manager on duty at the time. I was advised that the captain on the flight turned down the aircraft and it was now assigned to my ZZZ flight. I told the duty manager that I would need more information and would call him back after I arrived at flight operations. When I arrived; I called the operations supervisor and the maintenance supervisor. The issue with the aircraft was an intermittent gauge/sensor on the potable water system. This problem was chronic for about the last week. When the gauge/sensor failed to zero; it would shut down the water for the whole aircraft. I was told that the sensor needed to be replaced and they did not have a new one in stock. They could; however; take one from another aircraft and it would take about 8 hours for the fix. This is the same information that was given to the previous captain. I called the duty manager back and I was asked how I felt about taking an aircraft with the potable water system inoperative. I did not feel it was sanitary to take a 12 hour flight with toilets that would only dry flush. From an operational standpoint; it would also be a bad decision. Even if I would take it; it is very likely that the outbound captain would refuse the aircraft in ZZZ1 creating another problem there. I decided that it should be fixed. I also mentioned that it could be sent to ZZZ2; a 6 hour flight instead of 12 hours. I told the duty manager and maintenance that the aircraft would have to be fixed if I was to take it to ZZZ1. About 1 hour later; I called the maintenance supervisor and was told that they found a 'miracle fix.' I questioned him further; and was told that they were able to recalibrate the sensors and the aircraft was fixed and ready to go. This was contrary to what I had been told before. About 5 hours into the flight; the sensors failed and the potable water gauge showed 1 gallon. Fortunately; it did not fall to zero and we were able to have water the rest of the flight. We were fortunate. I think it is clear that the item was not fixed. It seems like it was a way to get us out of town without a real fix.

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Original NASA ASRS Text

Title: B777-200 CAPTAIN SUSPECTS MAINT OF FALSIFYING ACFT MAINT RECORDS REGARDING A CHRONIC POTABLE WATER SYSTEM FAULT TO MAKE IT ACCEPTABLE FOR A LONG RANGE TRANSATLANTIC FLT. SUPPOSEDLY REPAIRED SYSTEM ONCE AGAIN FAILS ENROUTE.

Narrative: PRIOR TO GETTING TO THE ARPT; I RECEIVED A CALL FROM THE CHIEF PLT AND THE DUTY MGR ON DUTY AT THE TIME. I WAS ADVISED THAT THE CAPT ON THE FLT TURNED DOWN THE ACFT AND IT WAS NOW ASSIGNED TO MY ZZZ FLT. I TOLD THE DUTY MGR THAT I WOULD NEED MORE INFO AND WOULD CALL HIM BACK AFTER I ARRIVED AT FLT OPS. WHEN I ARRIVED; I CALLED THE OPS SUPVR AND THE MAINT SUPVR. THE ISSUE WITH THE ACFT WAS AN INTERMITTENT GAUGE/SENSOR ON THE POTABLE WATER SYS. THIS PROB WAS CHRONIC FOR ABOUT THE LAST WK. WHEN THE GAUGE/SENSOR FAILED TO ZERO; IT WOULD SHUT DOWN THE WATER FOR THE WHOLE ACFT. I WAS TOLD THAT THE SENSOR NEEDED TO BE REPLACED AND THEY DID NOT HAVE A NEW ONE IN STOCK. THEY COULD; HOWEVER; TAKE ONE FROM ANOTHER ACFT AND IT WOULD TAKE ABOUT 8 HRS FOR THE FIX. THIS IS THE SAME INFO THAT WAS GIVEN TO THE PREVIOUS CAPT. I CALLED THE DUTY MGR BACK AND I WAS ASKED HOW I FELT ABOUT TAKING AN ACFT WITH THE POTABLE WATER SYS INOP. I DID NOT FEEL IT WAS SANITARY TO TAKE A 12 HR FLT WITH TOILETS THAT WOULD ONLY DRY FLUSH. FROM AN OPERATIONAL STANDPOINT; IT WOULD ALSO BE A BAD DECISION. EVEN IF I WOULD TAKE IT; IT IS VERY LIKELY THAT THE OUTBOUND CAPT WOULD REFUSE THE ACFT IN ZZZ1 CREATING ANOTHER PROB THERE. I DECIDED THAT IT SHOULD BE FIXED. I ALSO MENTIONED THAT IT COULD BE SENT TO ZZZ2; A 6 HR FLT INSTEAD OF 12 HRS. I TOLD THE DUTY MGR AND MAINT THAT THE ACFT WOULD HAVE TO BE FIXED IF I WAS TO TAKE IT TO ZZZ1. ABOUT 1 HR LATER; I CALLED THE MAINT SUPVR AND WAS TOLD THAT THEY FOUND A 'MIRACLE FIX.' I QUESTIONED HIM FURTHER; AND WAS TOLD THAT THEY WERE ABLE TO RECALIBRATE THE SENSORS AND THE ACFT WAS FIXED AND READY TO GO. THIS WAS CONTRARY TO WHAT I HAD BEEN TOLD BEFORE. ABOUT 5 HRS INTO THE FLT; THE SENSORS FAILED AND THE POTABLE WATER GAUGE SHOWED 1 GALLON. FORTUNATELY; IT DID NOT FALL TO ZERO AND WE WERE ABLE TO HAVE WATER THE REST OF THE FLT. WE WERE FORTUNATE. I THINK IT IS CLR THAT THE ITEM WAS NOT FIXED. IT SEEMS LIKE IT WAS A WAY TO GET US OUT OF TOWN WITHOUT A REAL FIX.

Data retrieved from NASA's ASRS site as of May 2009 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.