Liquid trade waste

Liquid trade waste is any discharge to a sewerage system other than sewage of domestic nature (i.e. wastewater from a hand wash basin, shower, bath, toilet or domestic laundry).

Sewerage systems are designed to safely collect, transfer and treat wastewater that is mostly of domestic origin. However, sewerage systems may also accept liquid trade waste discharges provided they are planned and controlled within acceptable limits.

Sound regulation and pricing of sewerage and liquid trade waste is a key component of the NSW Best Practice Management of Water Supply and Sewerage Framework PDF, 23.9 KB.

To assist councils in regional NSW with best-practice regulation of sewerage and trade waste, the department develops and updates Trade Waste Management Guidelines and related documents:

Approval to discharge

Businesses or government agencies proposing to discharge liquid trade waste to a council's sewerage system must have prior approval from the council responsible for regulating sewerage and trade waste in that area. Such approvals need Department of Planning, Industry and Environment’s concurrence. The department has provided assumed concurrence to all councils for low risk discharges.

The department also provides its concurrence to the council's approval of high risk and medium risk discharges, as well as authorising suitably qualified councils to 'assume concurrence' for medium risk discharges.

Liquid Trade Waste Management Guidelines

The NSW Government has issued an updated Liquid Trade Waste Management Guidelines 2021 PDF, 15374.2 KB.

These Guidelines outline the comprehensive NSW Framework for the regulation of sewerage and trade waste. The Guidelines are consistent with the National Wastewater Source Management Guideline, published by the Water Services Association of Australia in July 2012.

These Guidelines simplify council's approval of trade waste discharges by:

  • authorising councils to assume concurrence for low risk liquid trade waste
  • encouraging councils with significant experience in liquid trade waste regulation to apply for authorisation to assume concurrence for medium risk liquid trade waste
  • simplifying the approval process for liquid trade waste applications by government agencies.

By following the Guidelines, councils can:

  • meet their due diligence obligations and
  • comply with their sewage treatment work licences to achieve improved environmental outcomes
  • protect the service life of their sewerage assets
  • improve sewerage system performance, including reduced frequency of sewer chokes odour complaints and treatment process failures
  • simplify and speed up the approval process
  • provide a financial incentive to business and industry for cleaner production and waste minimisation
  • achieve full cost recovery to provide cost-effective non-residential sewerage and trade waste services
  • limit increases in residential sewerage bills as improved sewerage system performance may free up system capacity and minimise the need for infrastructure augmentation to serve new development and population growth

Information for plumbers

Plumbing work for liquid trade waste installations must now comply with the Plumbing Code of Australia and Australian Standard AS 3500 Part 2 Sanitary Plumbing and Drainage.

In regional NSW, local councils regulate any liquid trade waste discharge to their sewerage systems. Council's approval is required under section 68 of the Local Government Act 1993 for any discharge, other than domestic sewage, to the sewerage system.

Council’s requirements for liquid trade waste discharges into sewerage systems need to be in accordance with the Liquid Trade Waste Management Guidelines PDF, 15374.2 KB.

These Guidelines also provide important information for plumbers, including sizing and installation requirements for pre-treatment equipment (see Appendix F 'Overview of common methods of liquid trade waste pre-treatment')

Prohibited waste discharge

Plumbers should note that the Liquid Trade Waste Management Guidelines prohibit waste discharge from the following devices to any council sewerage system (see section 3.2.2):

  • Food waste disposal units – the connection of food waste disposal units (also known as in-sinkerators, in-sink food waste disposers, or garbage grinders) in non-residential premises to a council's sewerage system is not permitted. Existing installations in hospitals and nursing homes may be permitted to remain connected, provided the wastewater is pre-treated by an adequately sized grease arrestor.
  • Devices that macerate or pulverise waste – macerators and any other similar devices that are used for pulverising solid waste must not be connected by trade waste dischargers to a council's sewerage system. Solid waste includes, but is not limited to, animal waste, sanitary napkins, placenta, surgical waste and disposable nappies, bedpans and urine containers.
  • Alkaline hydrolysis waste – The wastewater generated by alkaline hydrolysis process (i.e. breaking down of human or animal tissue by using alkaline solutions at elevated temperatures and pH) is not allowed to be discharged to the sewerage system.
  • Discharge from float tanks – The discharge of water from float tanks (also known as floatation pods, iso-pods (isolation tank), sensory deprivation systems, or REST tanks (restricted environmental stimulation therapy tanks)) into a council’s sewerage system is not permitted. It is also not appropriate to dispose of such waste to septic tanks or on-site soak wells.
  • Discharge from solid food waste processing units (digesters/composters, etc.) – Discharge from a solid food waste processing unit (digesters/composters, etc) to a council’s sewerage system is not permitted without council’s prior written approval.

Further information

Further assistance to councils are offered by: