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What is a grease arrestor?

Grease arrestors are devices that reduce contaminants such as oil/grease and solids in wastewater so it’s safe to discharge to the wastewater network. They come in many shapes and sizes - for a full list of Unitywater approved grease arrestors, please refer to our pre-treatment requirements webpage.

Grease arrestors work by slowing the flow of wastewater down and directing the flow, so that oil/grease and solids remain in the arrestor. The diagram to the right illustrates how a grease arrestor with baffle walls, a common type of arrestor, slows and directs flow to remove contaminants.

Why do you need a grease arrestor?

Food businesses have the potential to produce trade waste that contains oil/grease and suspended solids at concentrations greater than a typical residential household. If these substances are allowed to pass directly to the wastewater network, they can build up, restrict flow, cause odours and blockages. Blockages can lead to overflows of sewage to the environment, private property and even inside people’s homes and businesses.

Appropriate management of trade waste from food businesses, including pre-treatment through an appropriately sized and maintained grease arrestor, is vital to protect your drainage, Unitywater’s wastewater network, the community and our environment.


Why do you need to maintain and service a grease arrestor?

The oil/grease and solids build up in the arrestor over time. If this is not removed, the arrestor will not function correctly. If design elements of the arrestor, for example baffle walls, are broken or missing, the arrestor will not function correctly.

This can lead to the arrestor getting blocked and overflowing or blockages occurring in the wastewater network.

Resources

Watch the following video for more information on why you need to maintain your grease arrestor.

We specify minimum pre-treatment requirements and servicing frequency as a condition in the trade waste permit issued to each customer.

Australian guidelines for fats, oils and grease:

Managing Food, Fats, Oils and Grease from Food Premises

Australian standards for grease arrestors:

AS 5215 (Int):2024 | Standards Australia Store

Smarter servicing records from 1 January 2027

Unitywater is introducing a new digital system for recording grease arrestor servicing. Trade Waste tags with QR codes will replace manual paperwork, making compliance easier and more accurate for Trade Waste Permit holders. Digital servicing records help us identify potential issues earlier, reduce wastewater network blockages and allow us to work proactively with businesses to prevent problems before they occur.

These tags are small metal plates with a QR code and unique identifying number, installed near your grease arrestor (typically close to the nearest tap). When your liquid waste contractor services your grease arrestor, they scan the QR code to instantly create a digital service record.

Key benefits:

  • No more lost or incomplete paperwork
  • Instant digital proof of servicing
  • Accurate, real-time compliance records
  • Reduced risk of permit violations

Some businesses participated in our trial program and already have a WasteID tag installed. Look for a small metal tag near the closest tap to your grease arrestor device. If this is the case, this tag will be replaced by a new Unitywater tag. Please advise Unitywater immediately if you need the WasteID tag to remain on your device.

If you don't have a QR code tag: We'll schedule installation before 30 November 2026.

Your obligations as a Trade Waste permit holder

  • Notify us if your grease arrestor hasn’t had a Unitywater QR code tag installed by 30 November 2026
  • Engage a liquid waste contractor who can scan QR codes and submit digital records
  • Maintain all servicing frequency requirements as specified in your permit

When will my tag be installed?
We're installing tags on a rolling basis from July through November 2026. Contact may be made with you if the team needs assistance in accessing the grease arrestor.

Will installation disrupt my business?
No. Installation takes only a few minutes and requires minimal access to your grease arrestor area.

What if I don't have a tag installed by 30 November 2026?
From 1 January 2027, you'll be unable to submit compliant servicing records, which may result in non-compliance with your Trade Waste Permit conditions. Please ensure you contact us if you haven’t had a tag installed by 30 November 2026 or if your tag is removed/damaged.

Can manual dockets be used after 1 January 2027?
No. Manual docket submissions will not be accepted after 1 January 2027.

What if my contractor doesn't have QR scanning capability?
You're responsible for ensuring your contractor can comply with the new requirements. If they cannot, you'll need to engage an alternative contractor.

Is there a cost for the tag installation?
No. Unitywater will install the QR code tags at no cost to permit holders.

What happens if the tag is damaged or removed?
Contact Unitywater immediately to arrange replacement. You remain responsible for ensuring all servicing is recorded digitally.

Questions about the Trade Waste QR code tag program?
Simply email the team at tradewaste@unitywater.com.