Grease traps & treatment equipment

Trade wastewater contains solids, oil, grease and other substances. If you discharge it directly to the wastewater system (sewer), it can:

  • cause blockages and overflows
  • overload wastewater treatment plants
  • pollute our rivers and beaches.

To ensure you don't cause any of these problems, you must:

  • have our approval to discharge trade wastewater
  • apply for approval before you install pre-treatment
  • use only pre-treatment items we've listed
  • use a licensed plumber to install the equipment.

What do you need to do?

Commercial trade wastewater customers

If you discharge commercial trade wastewater, you:

  • may be required to install standard items of pre-treatment
  • must select the appropriate pre-treatment technology
  • must only install pre-treatment that we've listed.

Industrial trade wastewater customers

If you discharge industrial trade wastewater, you:

  • must meet our acceptance standards
  • must install pre-treatment designed and sized to meet site-specific requirements
  • may need to engage a wastewater treatment specialist.

How do you install the right equipment?

Commercial trade wastewater

If you're discharging commercial trade wastewater, you must install standard items of pre-treatment. The type of pre-treatment required will depend on your business activities.

Learn about our pre-treatment requirements for Commercial trade wastewater.

Food businesses

Most food businesses only need to install:

  • in-sink and in-floor bucket traps
  • a correctly sized grease trap

Some processes may need additional pre-treatment, such as upstream grease removal devices or under sink pump units. To find out about pre-treatment requirements for food businesses, read Plumbing for retail food businesses.

Only use pre-treatment we've listed and size it to meet your maximum hourly flow rate now and into the future.

Read about Listed pre-treatment for food businesses to find out if a product is listed for use within our area of operations. 

Automotive businesses

Most automotive businesses need to install:

  • in-sink and in-floor bucket traps
  • an oil water separation system with a collection pit and pump.

Only use pre-treatment we've listed and size it to meet your maximum hourly flow rate now and into the future.

Read about Listed pre-treatment for the auto industry to find out if a product is listed for use within our area of operations

Other businesses 

Only use pre-treatment we've listed and size it to meet your maximum hourly flow rate now and into the future.

Read about Listed pre-treatment for other businesses to find out if a product is listed for use within our area of operations.

Industrial trade wastewater  

If you're discharging industrial trade wastewater, you must meet our acceptance standards

To find out more, read our Industrial customers - Acceptance standards and charging rates fact sheet

You may need to engage a wastewater specialist to design and install a site specific pre-treatment solution.

If you need to install a grease trap, read:

Only choose a grease trap model we've listed and have it installed by a licensed plumber in accordance with the Plumbing Code of Australia, 2012.

What you need to do
Why you need to do it

Engage a licensed plumber. When the work is complete, ask your plumber for a certificate of compliance.  

The grease trap must be installed according to the manufacturer's instructions, our requirements and the Plumbing Code of Australia, 2012.

Size the grease trap to meet your maximum hourly flow now and into the future.

An undersized grease trap will not treat your trade wastewater. We may ask you to install additional pre-treatment.

Install the grease trap as close to the source (kitchen area) as possible.

If you use long pipe runs, they can become clogged with grease. This can cause overflows in your property.

Install the grease trap so it drains by gravity to the wastewater system (sewer).

Using pumps adds complexity and additional costs. If your pump fails, the grease trap will overflow within your property.

Ensure your grease trap is regularly cleaned.

Grease traps must be pumped out regularly. Your waste contractor will pump out the contents of the grease trap, clean the internal surfaces and scrape the inside of the grease trap. 

We'll specify how often your grease trap needs to be pumped out.

Ensure adequate space above the grease trap (at least equal to the depth of the grease trap).

This allows enough space to open the grease trap lid, maintain it and get it pumped out.

Allow for safe and unrestricted access to inspect and service (pump-out) the grease trap.

Your waste contractor must park the waste tanker close to the grease trap. Our representatives need safe access to check the performance of the grease trap.

Consider the need for fixed pump out lines.

Some situations require you to install a fixed pump out line, eg multi-storey buildings.  

A fixed pump out line runs from outside a building to a point near the grease trap. This enables your waste contractor to connect a vacuum tanker to the fixed pump out line at street level and use a flexible hose (attached to the other end of the fixed pump out line) to empty the grease trap.

Shopping centres

If you manage a shopping complex or small shopping centre, you may need to install multiple grease traps.

Communal grease traps must have the capacity to process the combined greasy waste output of each retail food outlet. Extra capacity may also be needed to allow for future changes.  

Small complexes

For small complexes (that require less than 30,000 L total grease trap capacity), communal grease traps may be used. The maximum capacity for a grease trap is 5,000 L.

Separate grease traps are required for grouped businesses to ensure the limit is not exceeded. Small complexes can also choose to install centralised pre-treatment equipment, such as dissolved air flotation or equivalent.

Large complexes

For large complexes, centralised pre-treatment such as dissolved air flotation or equivalent is required. Where exceptional circumstances prevent the installation of a centralised pre-treatment system, we may approve alternative pre-treatment.

Under sink pump units

It's better for grease traps to drain by gravity to sewer. This causes fewer operating problems, but sometimes it's not possible.

If the sewer grade does not permit a gravity connection, the preferred design is to drain through the grease trap to a pump well and pump to sewer. The least preferred design is to pump to the grease trap.

To find out more, read our Grease traps - under sink pump units fact sheet.

Oil water separators remove free oil from wastewater. They must be installed according to:

  • the manufacturer's instructions
  • our requirements
  • the Plumbing Code of Australia, 2012.

Types of oil water separator technologies

Type of technology How it works
Coalescing plate separator This is a gravity separator with a plate pack fitted to remove oils and solids. It uses the difference in specific gravity (settling speed) between immiscible components of a liquid waste stream, such as engine oil and washwater.

The plates improve the gravity separation process by reducing the settling or rise distance. Wastewater is collected and pumped to the coalescing plate separator.
Vertical gravity separator This oil water separator uses a vertical cylinder design containing a continuous truncated conical spiral pack to separate non-emulsified oils and sludges from wastewater.  

Wastewater is collected in a pit and pumped to the vertical gravity separator. 
Hydrocyclone separator system This uses centrifugal force to separate oils from water.

Selecting and installing your oil water separator

Before selecting your oil water separator system, read about listed pre treatment for the auto industry

Before installing your oil water separator:

Service stations with under canopy forecourts
We have specific installation requirements for you. See our schematic diagrams for:

Service station with under canopy forecourt - coalescing plate separator

Service station with under canopy forecourt - hydrocyclone.