Grease arrestors reduce the amount of greasy waste flowing into the wastewater system, by allowing fats, oil and grease to rise to the top and solids to sink to the bottom.

Grease arrestors must be installed by licensed plumbers according to our trade waste requirements and the manufacturer’s instructions. Incorrect installations can affect the ability to service the grease arrestor to the required standard and allow greasy wastewater to discharge to the wastewater system where it can cause blockages and overflows to the environment.


  • We have specific requirements for grease arrestor sizing for the retail food industry
  • The walls and floor of grease arrestors must be impenetrable, and the inner surface acid resistant.
  • Grease arrestors may be constructed, prefabricated or precast. The design, material used and size must be accepted by Water Corporation prior to installation.
  • Where grease arrestors require baffles the minimum thickness is 19mm. Baffles constructed of uPVC or HDPE must be reinforced
  • Gas tight covers to an arrestor are required where:
    • There is vehicular traffic
    • There is pedestrian traffic
    • The arrestor is subjected to stormwater intrusion
    • The arrestor is installed inside a building
    • Light duty gas tight lids are recommended when grease arrestors are installed above ground
  • Ensure there is vertical clearance above the grease arrestor, greater than the maximum depth of the grease arrestor and allows servicing of the arrestor in accordance with our standards.
  • All above ground grease arrestor installations are required to have a platform and steps manufactured to Australian Standards 1657-2018 for safe access to inspect and maintain the grease arrestor.
  • Fixed suction lines shall terminate with a camlock fitting and ball valve adjacent to the grease arrestor and also where there is appropriate access for the liquid waste contractor to park their vehicle. Fixed suction lines shall not connect directly onto a grease arrestor.
  • Grease arrestors should be located exterior of the building wherever practicable.
  • A hose tap should be installed within 6 metres of the arrestor and must have an appropriate testable backflow prevention device fitted as required by plumbing standards.
  • The inlet connection cannot enter at the side of the grease arrestor.
  • Sample points can not be used as a relief disconnector gully.
  • Dishwashing machines and glass washers are not to discharge to grease arrestors.


  • All industrial waste grease arrestors are to be vented to atmosphere, refer to venting of a grease arrestor diagram for details.
  • Air admittance valves are not to be used on the grease arrestor vent or the sealed trade waste sampling point.
  • Chamber vents may be combined above the overflow levels of the highest fixture connected to the grease arrestors providing the resulting vent size is in the accordance with Table n AS/NZS 3500.2:2015.


All associated plumbing work is to comply with Water Services Licensing (Plumbers Licensing and Plumbing Standards) Regulations 2000 and AS/NZS 3500.1:2015 and AS/NZS 3500.2:2015.

Grease arrestor plumbing work case study