The addition of various agents to pre-treatment systems, such as grease arrestors, must be authorised by Power and Water. Authorisation will only be given after assessment of the substance/organism by a suitably qualified, independent third party. All costs of such assessment are to be borne by the Trade Waste customer.

Greasy waste is classified as trade waste and incorporates any liquid waste produced by a commercial business as a result of food preparation, cooking and cleaning activities, which is then discharged through the sewerage system.

Food preparation businesses produce a large portion of greasy waste. These businesses range from fast food outlets, supermarkets, butchers, bakeries, cafes and smaller takeaway stores.

Grease is released in a liquid or emulsified form but it can solidify as it cools and cause blockages in the sewerage system. This can result in a build-up in the system, leading to sewerage overflows into the environment, households and businesses.

You must have a Discharge Permit from Power and Water Corporation to discharge trade waste into Power and Water’s sewerage treatment system.

If your business falls under one of the categories below that produces greasy waste, please contact Power and Water to be guided through the process of obtaining a Trade Waste Permit:

  • Bakeries
  • Butchers
  • Cafeterias
  • Restaurants
  • Schools (with domestic kitchens)
  • Delicatessens
  • Kitchens in commercial operating facilities such as nursing homes, day care centres and hospitals and hostels
  • Hotels, motels or function centres
  • Cafes
  • Canteens
  • Supermarkets
  • Fast food outlets
  • Takeaway food shops
  • Caterers * Coffee shops
  • Ice cream shops
  • Cake making, baking or decorating

Businesses that produce greasy waste are required to install and maintain an adequately sized grease interceptor trap in accordance with Power and Water specifications. They must be an approved product and meet the minimum size of 1000 litres.

Grease arrestors trap the grease, oil, food waste and fats, greatly reducing the discharge of these substances into the sewerage system.

All kitchen fixtures in the food preparation areas such as floor drains, kitchen sinks, dishwashers, cleaners’ sinks and bin wash areas must be connected to the grease arrestor. All grease arrestors must be serviced by a licensed waste transporter at a minimum of once every three months, unless otherwise specified by Power and Water.

Power and Water’s Trade Waste Officers can help you work out the most appropriate sized grease arrestor for your business. This will be included as a condition of your Trade Waste Discharge Permit. The sizing of grease arrestors is generally based on a maximum flow rate of litres per hour (a minimum 1000L sizing applies), with the seating capacity used as a guide only, both are outlined below:

Plumbing and kitchen fixturesGrease trap allowances (per fixture in litres)
Single bowl sink150
Double bowl sink20

Port sink

  • single
  • Double

100
200
Floor waste50
Bain-marie50

Wok table

  • waterless
  • continuous

100
200
Bin wash area100
Cleaners sink50

Dishwasher

  • domestic
  • commercial
  • industrial

200
500
1000
Hand basin50
Pasta cooker150
Steam “combi” oven600
Brat pan/Industrial pot600
Restaurant seating capacityMaximum wastewater discharge volume (litres/hour)Grease arrestor required (litres)
Up to 6911001000
70-19915001500
200-39920002000
400-59930003000
600-79940004000
800-99950005000

Grease arrestors become less effective as oil, grease and food waste accumulate in them. They require regular cleaning to prevent blockages, odour problems and health hazards.

A grease arrestor must be pumped out completely and the internal surfaces scraped and/or hosed off during the service. This cleans the arrestor of grease, food solids and any other particles that may block the outlet pipe.

Your Trade Waste Discharge Permit will list the specific maintenance requirements for your grease arrestor. It is your responsibility to have the grease arrestor serviced every three months at a minimum. Some businesses have their grease arrestor cleaned more regularly to ensure the appropriate discharge requirements are met.

Grease arrestors must be cleaned out by a licensed liquid waste transporter. The waste transporter is required to remove the entire contents of the grease trap and dispose of the waste in accordance with the regulatory requirements. You will be charged by the waste transporter for this work.

To find a licensed waste transporter look under Waste Reduction and Disposal Services in your local business directory.

Here are some useful tips to best manage greasy waste water in your business and potentially save you money:

  • Reduce the use of fat, oil and grease.
  • Do not pour any oil directly down the drain or into the grease arrestor.
  • Scrape or wipe off to a bin rather than rinse excess food material or oil and grease from dishes, kitchen utensils and equipment.
  • Use quick break detergents.
  • Use sink strainers/screens to prevent food solids from going into drains.
  • Ensure all grease-bearing drain lines discharge into a grease arrestor.
  • Have your grease arrestor serviced regularly by a licensed waste transporter.
  • Train your employees in what they can and cannot put down the sinks and drains. Explain the purpose and function of grease arrestors.
  • Store your used cooking oil in a bunded area so that leaks and spills cannot drain into the sewer or stormwater systems

For more information please contact Power and Water Trade Waste team.