As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLT - PILOT REPORTED A STRONG MILDEW ODOR/STALE AIR IN THE CABIN. FLIGHT CREW WAS ABLE TO ISOLATE THE ODOR COMING FROM THE LEFT PACK. MAINTENANCE REMOVED AND REPLACED DIRTY WATER SEPARATOR BAGS PER MM 21-51-41-404. OPERATIONAL CHECK AND LEAK CHECK GOOD.