Fats, Oils, & Grease: Additional Information

Fats, oils, and grease (FOG) from food preparation can build up in sewer pipes. Over time, it can cause blockages that result in costly sewage backups or overflows. Restaurants and food service businesses can produce large amounts of FOG and are responsible for keeping it out of the sewer pipes. First, learn the basics about FOG and then read additional tips about handling grease at your business below. Also included at the bottom of this page is Seattle municipal code regarding FOG.


Grease Guidance for Commercial Customers

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Below are questions and answers for Seattle restaurants and food service businesses regarding the problem of grease.

What is a grease interceptor and how does it work?

Grease interceptors keep fats, oils and grease (FOG) from entering your sewer pipes. They can be located inside or outside of your kitchen. They hold wastewater long enough for grease in the water to cool, solidify and separate. Once the grease separates, it can be disposed of properly.

Do I need a grease interceptor?

Any business that handles food should install a grease interceptor. Even small food service providers like coffee shops need one. King County Public Health requires grease interceptors for all new or remodeled restaurants that apply for a plumbing permit. Refer to the 2009 Uniform Plumbing Code for sizing criteria.

How much does a grease interceptor cost? Where can I get one?

Grease interceptors vary in cost. A simple one starts at $3,000. Prices go up for larger or more complex installations. Please refer to the FOG Service Provider list (pdf) to find a contractor.

What if I don't install a grease interceptor?

FOG can block the sewer and cause a backup. Businesses must pay for cleanup and property damage. They also must close until a King County Public Health inspector confirms all health issues are resolved. If a business causes a blockage in the public sewer main, they may have to pay for cleanup and property damage. The business may also have to install a new or upgraded grease interceptor.

How often should I clean my grease interceptor?

Businesses must clean their grease interceptors. No more than 25 percent of an interceptor should contain food or FOG buildup. If too much food or FOG builds up, it will not work properly. Each business can decide on a cleaning schedule. Some will need to clean more often than others. Best practices, like scraping dishes before washing, will reduce the need to clean.

How do I clean my grease interceptor?

Many businesses use service providers to clean their grease interceptors. If you choose to clean your own grease trap, here is a video with basic instructions.


Seattle Municipal Code

Fats, oils, and grease are prohibited discharges.

  • Seattle Municipal Code prohibits the discharge of wastewater containing more than 100 parts per million by weight of fats, oil, or grease (SMC 21.16.300 A. 2).
  • A business is in violation if there is visual evidence of grease build-up originating from their private sewer line (SMC 21.16.300 B).
  • Food service businesses must install and maintain grease interceptors (SMC 21.16.310 A).
  • Businesses must clean their grease interceptors when they are more than 25 percent full of grease and food waste (SMC 21.16.310 B).
  • Businesses cannot use emulsifying agents, enzymes, bio-additives, or similar chemicals in their grease interceptors (SMC 21.16.310 B).
  • Businesses must pay penalties for non-compliance. Fees range from $250 to $5,000.