Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Less Severe; Flight Deck / Cabin / Aircraft Event Smoke / Fire / Fumes / Odor
Flight Crew Landed in Emergency Condition
Aircraft
During climb out from ZZZ; through approximately 9;000-10;000 feet the AFT LAV SMOKE master warning illuminated. Requested Flight Attendant (FA) 2 do a physical check of LAV status. Advised ATC of LAV smoke warning and advised we required a precautionary return to ZZZ. By time FA reported LAV clear status the warning extinguished. Both passengers and crew noticed an unusual odor in the cabin. First Officer (FO) noticed slight odor in cockpit. Advised ATC. Ran appropriate QRH and normal checklists and returned to ZZZ without further incident.Aircraft was on first flight after dual engine compressor washes. In talking with maintenance personnel after landing it was suspected that residual chemical from the washes was the most likely source of the smoke warning and odor. Aircraft was removed from service for further investigation.
CRJ-700 crew became aware of LAV smoke via master warning in cockpit; resulting in a return to departure airport.