Getting the fats, oils and grease waste under control is going to take an ongoing effort by all industry stakeholders;

  • Business owners

  • Manufacturers

  • Standards and Testing Agencies

  • Design Professionals

  • Plumbing Contractors

  • Waste Haulers

  • Public health inspectors

  • Sewer Purveyors


The tools in this site were developed to assist design professionals and contractors in determining the fats, oils, and grease (FOG) discharge for different types of food service operations.  The intent is to establish minimum yet acceptable standards for design based on national food service operation data.


Most of the fats, oils, and grease production values are based on 30 days.  The grease production assumptions are based on national sales averages for the varying types of food service operations.  There are also estimates for operational maintenance costs for based on the FOG production and storage for FOG that was provided.  There are also separate calculators for hydromechanical interceptor sizing as well as operational maintenance cost estimators.


Though some industry publications indicate it is acceptable to use up to 25% of the overall capacity of gravity interceptors for FOG storage, it is more appropriate to require any storage space to be in addition to the required volume needed to provide 30 minutes of retention time to ensure the FOG laden waste has the appropriate time for separation.  Some recent data suggests the retention/separation time is no longer appropriate with various types of waste and chemicals used in drainage systems, however, most current plumbing codes still list the requirement at 30 minutes.  Therefore, the gravity FOG interceptor sizing calculators on this site are designed to always include the required volume needed for separation to occur based on the 30 minute retention/separation time frame.

Again these tools just provide a reasonable minimum starting point, ultimately it is the responsibility of the design professional to ensure the design provided will properly serve the end user.  The business owners have a responsibility to maintain the designed service schedule and adjust it when necessary to ensure the business itself does not adversely affect the City infrastructure.  The sewer purveyors also have a responsibility to track the servicing of the interceptors, not just to see if a report was turned in, but the rules should require before and after pictures of each interceptor  at the time of service, which should also include a picture of the access cover secured as designed.

**The F.O.G. production values used in the tools provided are based on the values determined through data collected as part of the February 16, 2011 Brown Grease Study Report by Kennedy/Jenks Consultants performed for Clean Water Services.  The F.O.G. production per meal values for the varying categories of Food Service Operations (FSOs) established in this study have also been published by the American Society of Plumbing Engineers.**

fats, oils and grease production estimates and interceptor sizing calculators