Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 49; Flight Crew Total 307; Flight Crew Type 307
Situational Awareness; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural MEL / CDL; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Weight And Balance
Flight Crew Diverted; General Maintenance Action; General Flight Cancelled / Delayed
Procedure; Aircraft; Human Factors; MEL
Operated Aircraft X ZZZ-ZZZ1. Had MEL 38-XX-X (lavs not usable below 16;000 ft). At cruise Flight Attendant said no lavs were flushing. Contacted Dispatch and patched into maintenance to discuss problem. Maintenance was unable to find a fix; Dispatch and crew decided best option was to divert to ZZZ2. Ran QRH for diversion checklist; as well as overweight landing since we were overweight by 3;000 lbs. Requested Runway XXR. Landed [Runway] XXR taxi to gate with no issues.
B737 Captain reported being forced to divert when it was discovered during cruise that the lavs would not flush.