As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WATER NOT DRAINING IN AFT OF AIRCRAFT. LAV SINKS, GALLEY DRAINS BACKING UP. REPEAT. UNCLOGGED AFT DRAIN MAST, VERIFIED AFT GALLEYS AND AFT LAV SINKS ARE WORKING NORMAL, PERFORMED DRAIN MAST HEATER OPERATIONAL CHECK AS PER AMM 30-71-00 VERIFIED OPS CHECKS SATISFACTORY.