Section 890.1/Grease Interceptors and Separators
IPC 890 covers grease interceptor and grease separator requirements for commercial food establishments including sizing, installation, access, and maintenance provisions.
Commercial food service establishments that discharge grease-laden waste must install a grease interceptor or grease separator to prevent grease from entering the sanitary sewer system. A grease interceptor (also called a grease trap) is an in-ground or above-ground device that uses baffles and retention time to separate grease from wastewater by gravity. A hydromechanical grease interceptor (point-of-use device) is a smaller unit installed directly at the fixture. Section 890.2 requires grease interceptors on waste lines from pot sinks, pre-rinse sinks, floor drains in commercial kitchens, commercial dishwashers (unless they discharge through a separate indirect waste), and any fixture that receives grease-laden waste. Grease interceptors must be sized per the applicable standard (ASME A112.14.3 for hydromechanical, ASME A112.14.4 or IAPMO Z1001 for gravity devices) based on the flow rate from connected fixtures. Access for cleaning and inspection must be provided: gravity interceptors must have gastight covers that are readily accessible, and hydromechanical devices must be accessible without removing permanent construction.
Why this section exists
Fats, oils, and grease (FOG) from commercial kitchens solidify in sewer lines, causing blockages that lead to sewer overflows, backups into buildings, and environmental contamination. A single restaurant can discharge hundreds of pounds of grease per year. Municipal sewer systems spend billions annually on FOG-related blockages and overflows. Grease interceptors capture FOG before it enters the sewer, allowing it to be collected and disposed of properly. The sizing requirements ensure the interceptor has adequate retention time to separate grease from the flow of wastewater at peak discharge rates.
What plan reviewers look for
Plan reviewers check the plumbing plan for grease interceptor locations and verify all grease-producing fixtures are connected. They verify the interceptor size is based on the connected fixture flow rates per the sizing standard. They check that the interceptor is accessible for cleaning without excavation. They verify that dishwashers, food waste disposers, and non-grease fixtures are not connected to the interceptor (dishwasher detergents emulsify grease and reduce interceptor effectiveness). They check the discharge point from the interceptor to the building drain. They verify venting of the interceptor per trap and vent requirements.