Narrative:

Flight attendants reported blue toilet water significantly overflowed from lavatory just behind first class cabin. Flight attendants later reported blue water appeared to be flowing uncontrollably into cabin and that they were working to control spillage. Due to concern over where this fluid might leak and how it could affect the flight I requested priority routing into ZZZ, upon entering ZZZ airspace about 200 NM from landing. I also notified ZZZ ATC that I did not believe we needed crash fire rescue equipment but that they should be notified of our status. The overall situation never mandated declaration of emergency in my opinion so none was made.

Google
 

Original NASA ASRS Text

Title: A B757-200 REQUESTED PRIORITY LNDG DUE TO EXCESSIVE LAVATORY BLUE WATER LEAK AND CONCERN WHERE FLUID MAY LEAK.

Narrative: FLT ATTENDANTS RPTED BLUE TOILET WATER SIGNIFICANTLY OVERFLOWED FROM LAVATORY JUST BEHIND FIRST CLASS CABIN. FLT ATTENDANTS LATER RPTED BLUE WATER APPEARED TO BE FLOWING UNCONTROLLABLY INTO CABIN AND THAT THEY WERE WORKING TO CTL SPILLAGE. DUE TO CONCERN OVER WHERE THIS FLUID MIGHT LEAK AND HOW IT COULD AFFECT THE FLT I REQUESTED PRIORITY ROUTING INTO ZZZ, UPON ENTERING ZZZ AIRSPACE ABOUT 200 NM FROM LNDG. I ALSO NOTIFIED ZZZ ATC THAT I DID NOT BELIEVE WE NEEDED CFR BUT THAT THEY SHOULD BE NOTIFIED OF OUR STATUS. THE OVERALL SIT NEVER MANDATED DECLARATION OF EMER IN MY OPINION SO NONE WAS MADE.

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.