What was found
JUST AFTER T/O (BEFORE TRANSFERRING BLEEDS TO ENGINES) SMOKE AND HEAVY CONDENSATION IN THE COCKPIT. SMOKE IN CABIN(PASSENGERS NOTICED). DECLARED EMERGENCY DONNED MASKS IMMEDIATELY ASKED FOR RETURN TO DEPARTURE AIRPORT. COMPLETED CHECKLISTS AND LANDED BELOW MAX LANDING WEIGHT. NORMAL LANDING. DEICING PROCEDURES FOLLOWED FOR TYPE 1 AND 4. ENGINES AND APU RUNNING. FILLED OUT A FORM AT THE FBO TO ESTABLISH CONFIGURATION AND REQUEST FOR DEICING 1/4. FOLLOW THE AOM PROCEDURES FOR AFTER DEICING PROCEDURES. CORRECTIVE ACTION: REPLACED WATER SEPARATORS. OPS CHECK GOOD. IAW AMM 21-51-00