Trade waste and pre-treatment requirements

Not sure if you need a Trade Waste Permit? If your business does one of more of the following, you need a Trade Waste Permit.

  • discharges any liquid waste into Unitywater infrastructure, other than domestic waste (domestic waste is wastewater from a toilet, hand basin or sink)
  • washes up or cleans any utensil or apparatus that is a component of the business and then discharges the wastewater into Unitywater infrastructure
  • has a commercial/industrial process that produces a contaminated liquid waste (i.e. anything that is non-domestic liquid waste that contains chemicals or residue from a commercial or industrial process).
  • requires or has any pre-treatment devices to be installed on the property that will be connected to Unitywater infrastructure.

We recommend you seek advice from a qualified Hydraulic Consultant who has trade waste experience about what type of pre-treatment your business may require before you apply for your permit. Approved lists of grease traps, oil separators and other apparatus are available for download below the table. 

Pre-treatment requirements may include the following:



Commercial food outlets or manufacturers

Food-generating businesses are usually required to install and maintain a grease arrestor of at least 1000 litres as a condition of a Trade Waste Discharge Permit.

The Trade Waste advisor that manages your permit application will assess whether your business needs a grease arrestor and will calculate the size required as per the hydraulic plan.

Education facility or childcare centres

Schools with science laboratories may need a grease arrestor, neutralising trap or dilution tank/s. Tuckshops or food preparation areas that produce hot food meals will likely require a grease arrestor and your Trade Waste advisor will assist in this matter.

Shopping centres

Garbage storage and bin washing areas need to have a silt arrestor of at least 1000 litres. The area must be ringed by a gutter in the ground or bunded. If the area is greater than one square meter, it needs a roof that overhangs the drain/bund by at least 900mm or a stormwater diversion system.

Service station or mechanical workshop

Automotive and engineering industries are usually required to install and maintain an oil and solids/water separator of at least 1000 litres per hour capacity.

Each permit application will be assessed on the nature of oily waste to be treated, proposed treatment method and site location.

Hospital or Medical centre

Opticians, dentists, medical and veterinary surgeries may need one or all of the following: bottle trap strainers, plaster arrestor and/or silver recovery unit (for x-rays).


Laundromats need to install 1mm mesh lint screens. If temperatures are greater than 38°C, a cooling pit is required.

Industry and manufacturing

These include but are not limited to chemical manufacturers, pesticide manufacturers, metal finishers and regulated waste receivers. Your Trade Waste Officer is happy to advise you.

Approved lists (downloadable PDFs)


Hydraulic consultants are easy to find by searching online. They are also listed in the Yellow Pages under: Hydraulic Consultants and Services.

If you have already received approval from an authority other than Unitywater for a pre-treatment process, such as those below, please contact our Trade Waste team for consideration of your existing approval:

Grease arrestor: A grease arrestor is a device that will slow down the wastewater velocity to allow separation of greasy wastes. Grease arrestors must be serviced regularly (cleaning frequency depends on size, loadings etc.) to make sure blockages do not occur downstream or within the business premises.

Neutralising tank: Neutralising tanks are designed to accept laboratory wastes that have a high and/or low pH. The correct pH level allowed to be discharged is between 6 and 10.

Dilution tank: Dilution tanks are used generally as cooling tanks usually for commercial laundries that have wastewater that has high temperatures. The maximum temperature is 38 degrees Celsius. High temperatures can create hydrogen sulphides (rotten egg gas) that cause corrosion within the sewer network.

Approved lists (downloadable PDFs)