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The guidelines and regulations you need to know about regarding irregular, one-off trade waste disposal.

Wastewater discharge from business or industry, which is not generated from staff amenities or office facilities, is generally classified as trade waste. By law, any industry or business that needs to discharge industrial waste must obtain approval from us.

What is one-off discharge?

One-off discharge is where a business needs to discharge waste to the wastewater system due to unusual or non-routine circumstances. A one-off discharge may be a single discharge event or several related events conducted over a period of time, typically up to 6 months. A one-off discharge may be required for events such as construction site dewatering, industrial process failure, site redemption or adhoc product testing. Customers who don't have a trade waste permit must apply for one-off discharge.

What if the waste discharge period is longer than 6 months?

If your business needs to discharge for a period longer than 6 months, you will need to apply online for a trade waste permit.

Discharge from site dewatering is often for periods greater than 6 months, but is usually considered a one-off discharge as it is temporary. Approvals for this type of discharges will be reassessed at 6 month intervals.

How do I complete the application form?

The one-off discharge application form needs to be completed electronically. Please save a copy to your desktop first and complete offline. When completed, send the Excel worksheet to Alternatively you can fax it to (08) 6330 6691 or post to:

Commercial and Industrial Services Section
PO Box 100 
Leederville WA 6902

How long will it take to process the application?

Your application can take up to 10 working days to process.

How is my application assessed?

Applications for one-off discharge are assessed on a case-by-case basis. Approvals are based on a thorough investigation into the quality and quantity of wastewater, and the method and location of discharge into the wastewater system.

Your application will be assessed for compatibility with our wastewater system. We'll determine if the discharge can be accepted and any conditions that may apply. Conditions may include discharge limits, or the need for specified pre-treatment of the waste. We will provide an estimate of the expected quality and quantity charges and a one-off discharge agreement for your specific circumstances detailing the conditions of the discharge.

How much does it cost?

We calculate charges based on the quality and volume of wastewater discharged. These charges cover the costs for handling and treating the wastewater. An hourly rate applies for the performed by our trade waste officers, this includes assessing your application, conducting site inspections, sampling and administration.

Additional costs will be incurred if you require us to install a connection to the wastewater system to enable the discharge. Costs for external laboratory sample analysis may also apply. For more information view trade waste charges.

Other costs

Additional costs may be incurred for services provided by other organisations, such as:

  • supplying or maintaining your plumbing or waste treatment fixtures
  • disposal of any treatment by-products
  • treatment and disposal of waste by other means (i.e. other than by being discharged to the wastewater system).

You may also be subject to licensing obligations, and associated charges, from the Department of Environment Regulation or other regulatory bodies. Please contact the specific waste service provider, or the appropriate regulatory body, for information on these services and your waste licensing obligations.

Your obligations

You must monitor the discharge closely and ensure compliance with your agreement.

We must be able to accurately verify the volume and rate of discharge to the wastewater system during the discharge period. Typically, this will be done through an effluent water meter, which must be calibrated and maintained in an accurate working order for the period of the discharge. In some instances, you may be required to record daily meter readings and supply these to us.You must ensure that any pre-treatment fixtures are in good condition and maintained during the discharge. Poorly maintained fixtures become ineffective, resulting in non-compliant wastewater discharges.

What happens if you breach your one-off discharge agreement?

You must comply with all conditions associated with your agreement. There are penalties for breaching your agreement. Breaching your discharge agreement conditions could result in any of the following:

  • threats to the health and safety of our workers and the public
  • physical damage to the wastewater system
  • poisoning of the biological processes at our treatment plants
  • an inability to re-use treated wastewater or treatment by-products in industry or agriculture
  • threats to the environment