Marion Utilities recommends using the WERF sizing recommendations which are based on the flow rate into the interceptor and the desired grease and solids storage volumes.

Input the following information to calculate the interceptor size:

How many persons are or will be served in 1 hour during peak time?
How many hours are or will the facility be open each day?
Number of sinks with 1.5 inch drain to wash pots, pans and other kitchen utensils, often 3 compartments.
Number of sinks with 2 inch drain to wash pots, pans and other kitchen utensils, often 3 compartments.
Number of sinks with 2.5 inch drain to wash pots, pans and other kitchen utensils, often 3 compartments.
Number of sinks used for preparation of meats, vegetables, and seafood.
Number of sinks for rinsing of ware prior to washing.
Number of automatic dishwashers or clothes washers.
Number of pieces of cooking equipment with 1.5 inch drains, such as tilt skillets, brazing pans, rotisserie ovens, and woks.
Number of pieces of cooking equipment with 2 inch drains, such as tilt skillets, brazing pans, rotisserie ovens, and woks.
Number of pieces of cooking equipment with 2.5 inch drains, such as tilt skillets, brazing pans, rotisserie ovens, and woks.
Number of equipment cleaning fixtures, such as can washes, mop sinks, automated hood cleaning systems, and washing stations.
Number of waste food grinders or garbage disposals.
Number of floor drains in food preparation and serving areas.
 = Calculated maximum flow rate in gallons.
 = Using the above information, the recommended grease interceptor size in gallons.