As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT, IN MODERATE RAIN WITH ENGINE ANTI-ICE ON, THE AIRCRAFT EXPERIENCED A PRESSURIZATION ISSUE. DECLARED AN EMERGENCY AND DESCENDED TO 10000 FEET. MASKS DID NOT DEPLOY. FLIGHT LANDED WITHOUT INCIDENT. AIRCRAFT WAS GROUNDED. FOUND THE LEFT WATER SEPERATOR CRACKED. REPLACED THE WATER SEPERATOR ASSEMBLY IAW AMM 21-20-02.