As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: LAVATORY L2A-1L, L3F-1, AND L3F-1LC DO NOT FLUSH. EMERGENCY DECLARED; FLIGHT RETURNED TO DFW LANDING SAFELY. MAINTENANCE FOUND DISCONNECTED COUPLING ON LAVATORY L2A-1L TOILET ASSEMBLY CAUSING LEFT HAND LAVATORIES TO NOT FLUSH. RECONNECTED COUPLING AND ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK PER DMC-B787-A-38-42-41.