As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ABOUT 40 TO 50 MINUTES INTO FLIGHT, F/A NOTED AFT LAV WAS NOT FLUSHING AND BOWL WAS FILLING UP. FWD LAVATORY WAS ALREADY DEFERRED AND ON MEL. AIRCRAFT DIVERTED TO PHX AND MADE AN UNEVENTFUL LANDING. FOUND AFT LAV CLOGGED. REMOVED DEBRIS AND SERVICED PER BOEING M/M. FWD LAV STILL ON MEL.