Grease traps and other pre-treatment

Equipment required to pre-treat commercial trade wastewater

Commercial trade wastewater can contain solids, oil, grease and other substances. If it's discharged directly into the wastewater system (sewer), it can cause blockages and overflows, overload wastewater treatment plants, and pollute rivers and beaches. That's why you must install grease traps and other pre-treatment equipment.

Not sure if you're a commercial customer or an industrial customer?
Find out more about differences between commercial trade wastewater and industrial trade wastewater. If you're still not sure, call 13 20 92 on weekdays during working hours or email us at businesscustomers@sydneywater.com.au.


Pre-treatment requirements for your business type

If your business discharges trade wastewater, you must install standard items of pre-treatment. The type of pre-treatment required will depend on your business activities and processes.

The retail food industry (including shopping centres) and the motor trades industry have particular requirements for pre-treatment equipment. However, all businesses must meet our conditions to remain connected to the wastewater system.

Most retail 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, like upstream grease removal devices or under sink pump units.

You can learn more about selecting and installing a grease trap and other treatment equipment for retail food businesses. You can also find out more about pre-treatment requirements for food businesses from Plumbing for retail food businesses.

Only choose pre-treatment equipment we've listed and size it to meet your maximum hourly flow rate now and into the future. Select from our listed pre-treatment for food businesses to find out if a product is listed for use within our area of operations, and who supplies it. Then, you must have a licensed plumber install your grease trap according to the manufacturer's instructions and The Plumbing Code of Australia. If you manage a shopping centre, you may need multiple grease traps.

You'll need a Wastesafe transporter to regularly empty, clean and maintain your grease trap. Find out more about Wastesafe and select your Wastesafe transporter.

You might want to try our tips for managing waste to introduce cleaner production methods and reduce the amount of retail food trade wastewater you produce.

Grease trap requirements for shopping centres depend on the size of the complex and how much greasy waste they produce.

If you manage a shopping complex or small shopping centre, you might 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, and you may need to allow extra capacity to allow for future changes. 

We have different requirements depending on the size of your grease trap, and you may need to install additional treatment equipment. Find out more about selecting and installing a grease trap and other pre-treatment equipment for retail food businesses and shopping centres.

  • For small complexes (that require less than 30,000 L total grease trap capacity), you can use communal grease traps. The maximum capacity for a grease trap is 5,000 L. You'll need separate grease traps for grouped businesses to ensure you don't exceed the limit. You can also install centralised pre-treatment equipment, such as dissolved air flotation or its equivalent.
  • For large complexes (those with over 30,000 L total grease trap capacity) you must have centralised pre-treatment, such as dissolved air flotation or its equivalent. If exceptional circumstances stop you from installing a centralised pre-treatment system, we'll work with you and may approve alternative pre-treatment.

Whether you're a mechanic, panel beater, spray painter, mechanic, auto-recycler or car detailer, or you run a service station or a car wash, you need to follow our requirements to remain connected to the wastewater system. Most motor trades businesses need to install:

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

You can only use pre-treatment we've listed, and you'll need to size it to meet your maximum hourly flow rate now and into the future.

Find out more about selecting and installing an oil water separator and more about pre-treatment for auto trades businessesNote that we have specific installation requirements for service stations with under-canopy forecourts. 

Select from our listed pre-treatment for the auto industry to find out if a product is listed for use within our area of operations, and who supplies it. You must properly maintain your equipment according to the manufacturer's instructions to ensure you continue to meet our requirements.

It's worth exploring our tips for managing waste to introduce cleaner production methods and reduce the amount of automotive trade wastewater you produce.

Auto trades minimum pre-treatment requirements

Activity

Minimum pre-treatment requirements

Service station with under-canopy forecourt

Collection well with a sloped bottom and minimum working volume of 750 L

  • inspection opening on grill cover
  • level indicator in collection well
  • high level in collection well triggers flashing light
  • manual check of collection well before using keyed manual start switch
  • keyed manual start switch located close to pit and pump

Oil water separator system

Bunded area around oil water separator

Wastewater discharge point located outside the bunded area 

View the installation set-up with hydrocyclone.
View the installation set-up with coalescing plate separator.

Panel beating and spray painting
Car detailer
Mechanical workshop
Auto recycler

Collection pit with an operating capacity of at least 500 L

Oil water separator system sized according to influent flow rate (minimum size 1 kL/hr) 

View the installation set-up with coalescing plate separator.

Car wash – hand wash and pressure spray
Car wash – mechanical <12 kL/day

Roof and bund wash area to exclude rainwater and install in-floor bucket traps

Collection pit with an operating capacity of at least 500 L

Oil water separator system sized according to influent flow rate (minimum size 1 kL/hour)

No discharge of solvents to sewer

Pre-treatment requirements vary depending on the business. However, all businesses must meet our requirements to be connected to the wastewater system. You must only use pre-treatment equipment that we've listed and size it to meet your maximum hourly flow rate now and into the future.

Select from our listed pre-treatment for other businesses to find out if a product is listed for use within our area of operations and who supplies it. Then, you need to follow any installation and maintenance instructions from the manufacturer to ensure your equipment continues to meet our requirements.


Pre-treatment requirements for deemed processes 

Some businesses are deemed to have permission to discharge trade wastewater to our wastewater systems. They have what are known as deemed processes. Your business must still meet the requirements listed below or you could be disconnected. However, deemed processes do not attract trade waste fees and charges.

If you discharge trade wastewater and your business processes are not listed as a deemed processes, you must have our written approval. If your process isn't listed below or you're not sure if you have our written approval, contact us at businesscustomers@sydneywater.com.au. If you don't have written approval and you're discharging trade waste, you must apply at Sydney Water Tap in.

Not sure whether your business processes are deemed processes?
Apply for approval at Sydney Water Tap in and we'll advise you.

Deemed processes and their pre-treatment requirements

Deemed process Pre-treatment requirements

Beautician, doctor's surgery, funeral parlour, school (ceramic and pottery room), venetian blind cleaning

No pre-treatment required

Aquariums

Must meet Australian quarantine requirements

Building construction – slab formation>

No discharge to our wastewater system (sewer)

Pipework with open connectors to be capped at all times or have an internal device fitted

Mobile carpet cleaners

20-micron filter unit

Cooling towers

Discharge not to exceed 500 L/day

Dental surgery

Amalgam trap and segregation of waste amalgam

Dental technician

Plaster trap

Dog groomer, pet shop (retail)

In-floor bucket trap, no organophosphate pesticides to our wastewater system (sewer)

Dry cleaners

Solvent recovery unit

Florist

No herbicide to our wastewater system (sewer)

Hairdresser

In-floor bucket trap and in-sink bucket trap

Optical lens grinding

Solids settlement pit

Residential garbage bin-wash area

Roof and bund bin-wash area to exclude rainwater and install an approved in-floor bucket trap

Discharge directly to the wastewater system (sewer) via floor waste

Use only soap-based products to clean garbage bins or bund bin-wash area to exclude run-off from other areas and install approved diversion system*

Use only soap-based products to clean garbage bins.

* Fox Environmental Systems DD600S

Residential vehicle wash bay

Minimum 1,000 L/hour oil water separator system; 1,000 L general purpose pit

Display a sign stating 'No degreasing or mechanical work in the wash bay'

Locate vehicle wash bay on a roofed and bunded hard surface and install an approved in-floor bucket trap

Direct all washwater to the oil water separator or general-purpose pit via floor waste with an approved in-floor bucket trap

Sanitary bin washing

Screening and temperature control (less than 38° C)

Swimming pool (residential, hotel, hospital, club)

No open areas discharging rainwater to our wastewater system (sewer)

Train platform and internal carriage cleaning

In-floor bucket trap and in-sink bucket trap

No open areas draining to the wastewater system (sewer)

Wash water generated by the washing of painting and plastering equipment such as brushes, trays and spatulas (construction site only – medium to high-density developments, mixed developments, commercial and industrial developments)

Minimum 1,000 L general-purpose pit or solid settlement pit. Note: we must authorise all pre-treatment apparatus


Selecting and installing a grease trap

Grease traps are the most common form of pre-treatment for retail food and some other businesses. You need to properly install and maintain your grease trap to continue to meet our requirements. If you reduce the amount of waste you're producing, your grease trap will work better. You must never pour waste oil directly into the sink or you'll quickly overload your grease trap.

These fact sheets provide more information about grease traps:

Under-sink pump units
It's better for grease traps to drain by gravity to the sewer, as this causes fewer operating problems. However, 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 the sewer. The least preferred design is to pump to the grease trap. To find out more, read our Grease traps: under sink pump units (276KB) fact sheet.

Requirements when installing a grease trap

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.
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, such as 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.

Selecting and installing an oil water separator

Oil water separators remove free oil from wastewater. Before you choose your oil water separator system, you should find out about listed pre-treatment for the auto industry

Before you install your oil water separator, read our Coalescing plate separators: installation guide (250KB) and see our schematic diagrams for installing coalescing plate separators and hydrocyclones. It must be installed according to the manufacturer's instructions, our requirements and The Plumbing Code of Australia.

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 unmixable 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.