Skip to Main Content View Text-Only

The City of Portland, Oregon

Environmental Services

working for clean rivers

Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Ave, Suite 613, Portland, OR 97204

More Contact Info

Grease Interceptor Maintenance

grease trapCity of Portland staff inspects grease interceptors to ensure they are in good working condition and that food service establishments (FSEs) are pumping them out frequently to prevent discharges of fats, oils, and grease (FOG) to the city sewer system. City staff can provide training and technical assistance to FSEs. Here are some frequently asked questions and answers about grease interceptors. 

What is a Grease Interceptor?

A grease interceptor is located between kitchen drain lines and sanitary sewer lines. Grease interceptors capture the FOG that enters sink drains from food service activities such as food preparation, dishwashing and cleaning.

Hydromechanical grease interceptor (HGI)

Hydromechanical grease interceptors (sometimes called grease traps) are installed indoors under sinks and FOG conveyance fixtures. Their capacity is measured by the volume of water that flows through the fixture, which ranges from 20-50 gallons per minute.

Gravity grease interceptor (GGI)

Gravity grease interceptors are installed outdoors and may be above ground or underground. These devices separate FOG and food waste from wastewater in large tanks that range in size from 1000 to 4000 gallons. 

Why is it important to clean and maintain my grease interceptor?

A poorly operating or improperly maintained grease interceptor will allow FOG to enter sewer lines.

An efficiently operating interceptor needs proper maintenance. Not removing FOG and solids from the grease interceptor frequently enough can cause private drain line blockages, back-ups, foul odors and loss of business. Even worse, a FOG obstruction in the city sewer line can cause a sewage overflow to the environment or in other buildings. The city will take enforcement actions against an FSE that causes a grease obstruction in the city sewer. The FSE could also be liable for any damages caused to other businesses or residences impacted by the obstruction. 

sewer overflowHow often should I clean my grease interceptor?

You should pump out hydromechanical grease interceptors located inside at least once a month, and the larger outside gravity grease interceptors at least every three months.

As of January 1, 2012, City of Portland rules require FSEs to establish and maintain a consistent cleaning frequency schedule for all grease interceptors. On-call or as-needed are no longer acceptable cleaning frequencies. City staff will work with FSEs to determine if cleaning schedules are adequate to keep grease interceptors working properly.

Who should clean my grease interceptor?

FSEs are required to regularly clean grease interceptors to acceptable standards and provide the city with timely cleaning and servicereports. Using a pumping company that is part of the Preferred Pumper Program ensures that cleaning and maintenance meet standards established by regional municipalities. Standardized procedures increase the likelihood that grease interceptors are cleaned correctly, and keep FOG out of the sewer system.

Pumpers registered with the Preferred Pumper Program certify that they will follow pump-out criteria. The city encourages commercial and institutional FOG generators to use a Preferred Pumper.

For more information, go to

How much does this service cost?

Preferred Pumpers charge a flat rate for hydromechanical grease interceptors. Preferred Pumpers charge by the gallon for gravity grease interceptors. The city recommends getting several quotes to get the best price and service to meet your needs.

City staff can provide technical assistance and help FSEs save on cleaning costs by using FOG reduction techniques and Best Management Practices. 

For More Information

Contact Ali Dirks at 503-823-7993 or You can also call 503-823-7093 to speak with a Grease Inspector.