Any business (including food businesses) that discharges or wants to discharge trade waste into the wastewater system must apply for a trade waste discharge consent.

Email Water.services@selwyn.govt.nz to book a free pre-application meeting with our engineers.

We work with business customers to identify their level of risk, to help them understand their obligations and to assist them to comply at the lowest possible cost with our Trade Waste Bylaw. We recommend that you engage with us as early as possible to discuss your project.


What is trade waste?

It is any liquid discharged into the wastewater (sewer) system from trade premises during commercial or industrial processes. Trade waste is not necessarily toxic but can be harmful if discharged directly into the sewer without first having problem substances removed.

It is important to manage trade wastewater correctly, to prevent:

  • sewer blockages or spills
  • damage to the wastewater system
  • health hazards for people
  • harm to the environment.

Examples of trade waste customers are:

  • meat processing plants
  • food manufacturers
  • metal finishers
  • car washes
  • hospitals
  • laundries
  • and chemical plants

How to apply for a consent?

The Trade Waste Bylaw 2016 [PDF, 1332 KB] sets certain controls on the discharge of potentially harmful trade waste. Any business (including food businesses) that discharges or wants to discharge trade waste into the wastewater system must apply for a trade waste discharge consent. No plumbing or drainage works associated with the discharge of trade wastewater to the Council’s system is to be started without agreement from the Council.

Our application process

  1. If you are planning to discharge trade waste into our sewerage system, you must contact us to discuss your plan. The best way to do so is to request a pre-application meeting with our engineers. You can do so by emailing water.services@selwyn.govt.nz
  2. During the meeting, our engineers will assess your project in detail and advise you on the best way forward. You might be required to install an onsite waste treatment plant to comply with our bylaw.
  3. We assess all commercial building consents and monitor new activities (change of use) that we believe may require a trade waste discharge consent to be applied for.
  4. You will need to submit a complete application using our online forms.
  5. We will acknowledge your application in writing within 10 working days of its receipt.
  6. We will compare the characteristics of our trade waste to the limits stipulated in the Schedule 1A and 1B of our Bylaw to determine whether your discharge requires consent.
  7. We will calculate your trade waste charges based on the volume and, if required, content of your trade waste supplied in your application. You will be invoiced on a yearly basis
  8. Once the Trade Waste Consent has been issued for your business we will contact you to discuss any additional sampling procedure. An appropriate sampling point and means of flow recording must be provided.

Our online application forms:


Frequently Asked Questions

Why is a discharge consent necessary?

It helps us to protect our workers, our infrastructure and the environment you live and work in, by controlling the quality and quantity of discharges into the sewer system.


How is the trade waste monitored?

  • One of our officer may inspect your premises and its trade waste discharge before issuing a consent or a variation to a consent conditions.
  • Regular tests may be undertaken as part of a monitoring schedule dependent on the type of business involved.
  • A business may be required to pay for the volume of wastewater it discharges. Using a water or flow meter will help with calculating charges.
  • A business must be able to supply documentary proof that cleaning is occurring – particularly with regard to grease trap or sump maintenance.

What happens to a business that does not comply?

  • If a business does not comply with the provisions of its discharge consent, that business could be put into a higher risk category and consequently have to pay a higher consent fee or have its consent cancelled.
  • Non-compliance, including non-payment of the consent fee and therefore discharging without a consent, can also result in prosecution under the Local Government Act.

What can I do with waste that cannot be discharged to the sewer?

A qualified contractor must remove the waste and take it to an industrial treatment plant.

How do I calculate the mass of a substance in a trade waste discharge?

You determine the mass of a substance by multiplying the concentration of the substance in the discharge by the volume of the discharge over 24 hours.
For example: 150 grams per cubic metre of oil and grease x 100 cubic metres discharged over 24 hours = 15,000 grams or 15 kilograms