grease traps

The Quick Guide: What is a Grease Trap and How Does it Work?


A grease trap play an important role in removing contaminants. Read here to see the quick-and-dirty of what it is and how it works.

Curious about grease traps?

Did you know that huge blobs of fat are filling our sewers? Recently, workers in London discovered the largest of the aptly named “fatbergs” ever recorded. It weighed in at an estimated 130 metric tons and was the size of 11 double-decker buses.

And it’s all coming from your kitchen sink.

Well, yours, your neighbors, and the restaurants down the street. The oils and fats you wash down your sink join with similar fluids from your neighbor drains. After it passes through miles of pipe, it eventually settles and solidifies with other waste in the sewer system.

Fortunately, there’s an easy fix to this fatberg crisis.

It’s called the grease trap. When you’re ready to impress your friends with your grease cleaning wisdom and start the war on fatbergs, read on.

What’s a Grease Trap?

Grease traps are most commonly found in restaurants. Wastewater flows through the grease interceptor, which separates the fats, oils, and greases (FOG) from the rest of the liquid.

The FOG is 10% to 15% less dense than water, so it rises to the top. Tiny walls inside the grease interceptor tank control the flow of water, capturing this free-floating grease. The rest of the fluid drains from the bottom of the trap into the sewer lines.

When this layer of grease grows thick enough, you must empty the trap. Some people create a grease trap cleaning schedule to ensure it doesn’t overflow.

If it does, watch out! You’re in for the worst mess of your life.

Why Do I Need One?

As we already mentioned, sewers aren’t designed to handle FOG. It blocks sewer lines causing backups and eventual overflows. Overflows are a significant health risk and require huge sums of money to clean up.

For this reason, states like California have included grease trap laws in their legislation. They outline the methods food establishments must use to dispose of grease. Hint – flushing it down the drain isn’t an option.

Check your city and state to determine which laws may apply to you.

What Do I Do with the Grease?

The simple answer is to toss it in the nearest trash can with your other solids.

The grease is harmless in landfills. In fact, many helpful insects use the FOG as a food source. Note: never feed the FOG to pets; in its present state, it can kill them.

You can also recycle and recover the FOG. The resultant brown grease can be repurposed for things like fuel for boilers.

Some companies also provide services that pick up your used grease. They process the grease so it can be used for biofuel and feedstock. Afterward, they rebrand your FOG and sell it to the appropriate manufacturer.

Before you ask, the answer is no. You won’t be seeing any of those profits.

What’s Next?

Now that you’ve learned about grease traps, it’s time to decide whether you need one. If the answer is yes, you’ll have to contact your local contractor for installation. They’re not a DIY type of project.

If you loved this article, skip over to our library to learn more about grease, cooking oil, and other smart alternative fuels. So long and good luck!

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