Fats, Oil, and Grease

Water containing high concentrations of fats, oil, grease (FOG), and other food waste can build up and block sewer pipes. Clogged sewer pipes can cause raw sewage to back up into homes and businesses or overflow into streets and streams.
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The Problem with FOG

FOG is a problem for all of us. It doesn't break down in water, separates from other liquids, and sticks to pipes. Slowly building up on the insides of pipes, FOG can cause blockages in yours or others pipes. FOG blockages can cause sewer backups and overflows that can endanger public health, damage private property, harm the environment, and result in violations.

For Businesses

Restaurants and other food service establishments are primary sources of FOG. The more than 3,000 food service establishments in Portland and Lake Oswego pay additional fees for wastewater flowing to the sewer system because they require extra sewer cleaning and treatment. These fees ensure other ratepayers do not pay the additional costs. Sewage collected from other commercial customers containing large amounts of FOG, organic material, suspended solids, and food waste also pay a higher sewer fee.

Oregon Plumbing Specialty Code requires all food service establishments to have kitchen fixtures connected to grease interceptors when there is new construction, redevelopment, tenant improvement, or a change in ownership or occupancy.

More information on grease interceptors

Sewer rates are based on pollutant concentrations, FOG treatment, and best management practices at each establishment. City staff visit with each affected business to verify conditions and provide information.

More information on sewer charges

More information on best management practices

For Residents

FOG from cooking may look harmless as a liquid, but it gets thick and sticky when it cools. That means if you pour FOG down your drain, it sticks to pipes and eventually causes clogs and harmful overflows. Here are some handy tips for managing FOG and preventing clogged pipes and sewer backups.


  • Scrape food scraps into the trash or compost bin.
  • Use a strainer in the sink to catch food scraps and other material. Empty the strainer into the trash or compost bin.
  • Pour grease into cans, let it harden, and throw the can with FOG into the trash.
  • Stop using your garbage disposal or minimize its use. Small bits of food stick with FOG to pipes, causing additional build-up.
  • Wipe pots, pans, and dishes with dry paper towels before rinsing or washing them, then throw paper towels in the garbage or compost bin.
  • Rinse dishes and pans with cold water before putting them in the dishwasher.


  • Never pour FOG down a sink drain or toilet.
  • Don't use cloth towels or rags to scrape FOG off plates and utensils because FOG will drain to the sewer when you wash the towels.
  • Don't run water over dishes, pans, fryers, or griddles to wash oil and grease down the drain.

The City’s Role

As Portland grows, so do the demands on our sewer system. Some areas of Portland, especially areas with a lot of food service establishments, require more frequent sewer maintenance because of grease blockages. The City has designated these as accelerated grease cleaning areas and cleans sewer pipes in these areas two to four times a year.

Rules and Regulations

City Code Chapter 17.34 Sanitary Discharges gives Environmental Services direction and authority to administer the Cut Through the FOG program and describes Portland's sanitary and combined sewer discharge regulations and the City's Industrial Pretreatment Permit Program. Chapter 17.34 also authorizes the bureau's Director to establish administrative rules for sanitary discharge control programs. Sub-section 17.34.050 allows the director to require pretreatment of sewage discharges.

The city adopted ENB-4.26 - Fats, Oils, and Grease Removal Program Administrative Rules in December 2011.

The city adopted ENB-4.25 - Extra Strength Sewer Charge Program Administrative Rules in December 2011.

Chapter 17.36 Sewer User Charges describes the extra-strength sewage charge for wastewater discharged to a city sewer, either directly or indirectly, if the discharge has a biochemical oxygen demand or a total suspended solids concentration in excess of concentrations determined by the director.