What are Grease Traps & Interceptors?

Grease Traps/Interceptors are pretreatment devices used to prevent fats, oils, and grease (FOG) from entering the wastewater collection system. These devices separate the oils, greases, and food solids, allowing the remaining wastewater to flow through the sanitary sewer system.

Who's Required to Install a Grease Trap/Interceptor?

Per Tempe City Code, Sec. 27-22, all food service establishments (FSE) in Tempe are required to install either an indoor grease trap or an outdoor grease interceptor. The type, size, and maintenance of the device required is dependent on a variety of factors (see information below).

Grease Traps:                                                                

What: Grease traps are typically smaller grease protection devices (minimum size is 50gpm/100lb capacity) designed for smaller operations. See

Where: Typically, grease traps are located indoors. However, there are some models that can be installed outside.

When: Grease traps can be installed when there are four or fewer kitchen fixtures (sinks, floor drains, etc.) connected to the grease waste line. Note: if you have a commercial grade dishwasher at your facility, you must install a grease interceptor to accept its wastewater.

Cleaning: Per Tempe City Code, Sec. 27-22, grease traps are required to get serviced by a non-hazardous liquid waste hauler (NHLWH) monthly, or more frequently if necessary.

Grease Interceptors:

What: Grease interceptors are larger grease protection devices. The minimum size is 500 gallon capacity and the maximum size is 2,500 gallon capacity.

Where: Due to the large size of these devices, grease interceptors are located outside the building.

When: Grease interceptors shall be installed when there are over four fixtures connected to the grease waste line and/or when a facility uses a commercial grade dishwasher.

Cleaning: Per Tempe City Code, Sec. 27-22, grease interceptors are required to get serviced by a non-hazardous liquid waste hauler (NHLWH) quarterly, or more frequently if necessary.

Why is it Important to Properly Manage Fats, Oils, and Grease?

When not managed properly, fats, oils, and grease can form large build-ups called "fatbergs" within our wastewater collection system. These fatbergs clog pipes and lead to sanitary sewer overflows, which are a danger to our residents and our environment.

Reference Materials:

• Grease Trap Installation Detail
• Grease Interceptor Installation Detail
• Grease Interceptor Sizing Spreadsheet

Please visit the Pretreatment Documents & Information page for other FOG documents.

If you have any questions regarding the city's FOG Program, please call Environmental Services at (480)350-2678.