Sampling is normally carried out for businesses with discharge volumes of more than 1245m³ per annum. This is to monitor trade waste compliance and to ensure trade waste fees are charged accordingly.

Routine sampling usually takes place once every quarter and the sampling costs are included in Christchurch City Council's trade waste charges. However, if more frequent sampling is necessary to ensure continuous compliance then the additional sampling will be at the customer’s expense.

Depending on the type of business and wastewater characteristics, Council will specify the sampling criteria and organise the relevant sample containers.

Sampling is carried out either automatically or manually to suit the characteristics under review.

An appropriate sampling point and means of flow recording must be provided. Once the Trade Waste Consent has been issued for your business the Council will contact you to discuss the sampling procedure.

Automatic sampling

This sampling is the most representative method and involves collecting individual samples and then combining them into one composite sample.

Individual samples are taken at a set frequency. Automatic sampling is the usual method for routine sampling and these samples are used for the standard Trade Waste Consent monitoring parameters:

  • pH
  • Suspended Solids
  • Biochemical Oxygen Demand (BOD5).

Other parameters such as heavy metals may also be analysed on these samples depending on the nature of the business and where the time taken to sample and/or the sample container do not affect the reliability of the test result.


Manual sampling

This sample is collected at a particular instance and represents conditions existing at that moment. Typically, this type of sample is used where only a small number of samples (e.g. two or three) are taken manually over a working day.