How Do Grease Traps Work?

August 11, 2021
Wet Waste
Professional Kitchen — Wet Waste in Gold Coast, QLD

If you run a commercial kitchen, food manufacturing, or food preparation business, you’ll need to install and maintain a grease trap.

When cared for well, a grease trap will capture any food solids, fats, and oils that wash down the sink when cooking or preparing food. Without a trap, your business risks thousands of dollars worth of repairs for blocked, clogged, or cracked pipes.

Here at Wet Waste, we are talking about what a grease trap is, how they work, and how you can ensure your trap continues running at optimal capacity.

What is a Grease Trap?


Grease traps are also commonly known as grease catchers, converters, interceptors, FOG traps, or grease management devices. They’ve existed in some capacity for over 100 years.

You’ll find grease traps in any commercial establishments where workers prepare food, such as:

  • Cafes
  • Takeaways
  • Restaurants
  • Pubs
  • Schools
  • Universities
  • Bakeries
  • Hotels and motels
  • Childcare centres
  • Retirement homes

Essentially, a grease trap is a large plumbing device designed to intercept grease and oil. When wastewater containing these substances washes down the sink, it will travel into the grease trap before entering the drainage system.

Keep in mind that grease traps will not trap large amounts of grease—just trace amounts typically found in commercial wastewater. You should still avoid pouring oil and other solids down the sink.

How Grease Traps Work


Water is about 10 to 15% denser than vegetable oil and animal fats. Grease traps work on this principle—water and grease will not mix. Instead, oils and fats will float on top of the water.

As wastewater enters a grease trap, the flow rate reduces, giving the wastewater time to cool. Once cooled, the wastewater will separate into three layers—grease at the top, water in the middle, and solids at the bottom.

The grease catcher will trap the risen grease using a baffle system. Some catchers also feature a removable filter for catching solids, reducing the amount that settles at the bottom of the trap.

The separated water then escapes through a designated outlet and enters the drainage system.

Grease and solids will build up over time. If left for too long, these substances could escape through the water outlet—or even clog up the inlet. To avoid these problems, make sure to maintain your grease trap properly.

Cleaning and Maintaining Grease Traps


To check if your grease trap is running smoothly, make sure:

  • The lid closes firmly, leaving no gaps
  • The lid and walls are free from chips and cracks
  • All baffles are in place

If you notice gaps, cracks, or broken baffles, contact a professional to book a thorough grease trap cleaning and maintenance service.

Save Money on Pipe Repairs


Grease traps are vital installations for any business working in food manufacturing or production. By preventing oil, fats, and solids from entering your drainage system, you’ll avoid the inconvenience and potential hefty cost of repairing blocked pipes.

At Wet Waste, we offer cleaning and maintenance services for commercial grease traps. Call us today 1300 552 017 to book a service and keep your drainage system clog-free.

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Liquid Waste Removal and Septic Tank Cleaning on the Gold Coast, Brisbane, Redlands, Logan and Ipswich Shires.

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