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Cease the Grease

Invasion of the Grease Monster


Commercial food preparation establishments are responsible for proper disposal of their fats, oils, and grease (FOG). Food serving businesses must keep and maintain a grease trap or grease interceptor, which is designed to stop grease from entering the main sewer line. However, if the interceptor or grease traps are not cleaned out, it too becomes clogged and can lead to a blocked sewer line and potential sanitary sewer overflow.

Millions of dollars are spent each year cleaning out sewer pipes clogged by FOG. To avoid this problem, restaurants must check with their local water utility about grease trap rules and regulations.


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Grease Traps

grease trap skematicMaintaining your restaurant's grease trap or grease interceptor is a must for proper operation and is often required by city code. Some problems associated with improper maintenance include sewage backing up into your business, rancid odors, expensive cleanup and repair, potential contact with disease-causing organisms, and higher operating costs.

Grease traps capture grease from the wastewater flow. Grease traps slow down the flow of hot greasy water, allowing it to cool. As the water cools, the grease separates and floats to the top of the trap while the water flows down the pipe into the sewer. The grease is trapped by baffles that cover the inlet and outlet of the tank. If the tank is not pumped frequently enough or the drain lines are not maintained properly, backups and blockages occur.

Grease trap test sampleThe design of a grease trap is simple and there are many styles and sizes to choose from. Check with your control authority to have the correct grease trap installed properly at your food service establishment.

Grease traps come in various designs and sizes. Plastic grease traps are now available at most restaurant supply stores. Before you purchase a grease trap, check with your control authority first.

For assistance in determining when under-the-sink grease traps need to be cleaned, refer to the Plumbing and Draining Institute's spreadsheet for calculating cleaning frequency.

For large, in-the-ground grease traps: Cleaning the grease trap involves vacuuming up all the contents, scraping the built-up grease on the walls, and sucking up the remainder while rinsing with a pressure washer. A properly cleaned grease trap should have nothing left in it.

When the grease hauler or renderer has finished cleaning the grease trap, several components must be in place. Both the hauler and the business must maintain records of the cleanout on a manifest or trip ticket. These documents will verify who generated the grease, when the trap was cleaned, who cleaned it, and how much was pumped out, as well as when and where the grease was disposed of.

Check out our 2015 city-by-city guide to grease Interceptors!

Kitchen BMPs

Wipe pans with a paper towel before rinsing with cold waterUnder-the-sink grease traps may be great for small spaces, but they require constant upkeep. Under-the-sink grease traps need to be cleaned out every day to avoid odors. Cleaning an under-the-sink grease trap should be done after hours, when there is no food handling. You can dump the grease into a container and have a renderer or permitted waste hauler service the container as required by local regulations. It is often required to keep a log of when the under-the-sink grease trap was last cleaned, and who cleaned it.

Be careful not to burn or scorch fry oil. To extend the life of the oil you can strain and filter it to remove the impurities.

Used fry oil is actually a valuable commodity and can be recycled into many useful products. Some renderers may even pay you for it.

Have plenty of easily accessible paper towels near the prewashing station to dry-wipe the grease off of pans before running them under water. The prewashing station and dishwasher must drain into a grease trap.

Scrape excess food off of pots, pans, and plates; don't use the garbage disposal in the sink. When food scraps decompose in the grease trap, they release acids that eat through the walls of the grease trap, drastically reducing its lifespan.

Floor drains and wash buckets should empty into a grease trap. It is illegal to dump a wash bucket where it will wash down a storm drain.

You can place posters around the kitchen reminding employees about proper grease management. [See our Publications section for examples.]