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Trade WastePara Wai Tauhokohoko

Hastings District Council owns and operates the Wastewater Treatment Plant in East Clive where all the wastewater from Hastings, Havelock North, Flaxmere, Whakatu and Clive is treated before it is pumped into Hawke Bay via a long sea outfall.

What is Trade Waste and what does it mean for your business?

Any business that wishes to discharge trade waste that exceeds any of the limits in Schedule B of Chapter 7 of the Bylaw must apply for an approval to discharge controlled wastewater.  Approval must be obtained before starting the discharge.  The approval will state the limits for the characteristics the business is allowed to discharge.

Anyone wishing to discharge trade waste into the Separated Industrial Network (not available in all areas) must have approval to discharge controlled wastewater regardless of the volume or flow rate or any other characteristics.  No sewage may be discharged into the Separated Industrial Network.

Any trade waste discharge that is within all limits of Schedule B of Chapter 7 of the Bylaw is considered a permitted discharge and does not require approval to discharge. Depending on individual circumstances, the discharge could be subject to trade waste charges.

Trade waste discharge in the pressure sewer system in the Irongate Road East Industrial area is severely restricted. The information in here does not apply to discharges in this development. Contact Hastings District Council for further information.


Approval means a written Approval to discharge Controlled Wastewater, issued by Hastings District Council.
Bylaw means the Hastings District Council Consolidated Bylaw. Chapter 7 is for Water Services.
Controlled Wastewater means any wastewater that has characteristics greater than the limits listed in schedule B in the Bylaw.
Characteristics means volume, flow rate, pH, solids, oil and grease etc.
Grease Trap means equipment designed to reduce the amount of oil and grease from wastewater discharge.  It is important that they are sized correctly.
Oil and Grease means cooking oil, animal fat, butter etc.
Permitted Discharge means any Trade Waste discharge that is equal or less than the limits in the Bylaw.  Many small businesses can meet the “Permitted” standard by using pre-treatment.
Petroleum Hydrocarbons means Petrol, Diesel, hydraulic oil, lubricants, engine oil etc.
Pre-treatment means any modification made to the characteristics of the wastewater before it is discharged from the premises into the sewer. This can be by screening to reduce the amount of solids, Grease Trap to reduce oil and grease etc.
Schedule B means the schedule in the Bylaw that lists the limits for discharge characteristic for trade waste that are permitted discharge – less than or equal to the limit listed = permitted discharge.
Sewage means human waste and includes septage and swimming pool and spa pool water.
Trade Waste means any wastewater generated from activities which are not primarily residential in nature (but may include sewage).
Trade Waste Officer means the council staff that deals with any matters relating to trade waste, such as answering questions and providing various information, monitoring discharges, issuing Approvals etc.

Application for controlled wastewater discharge approval

Please contact the Trade Waste Officer or the Service Assurance Manager on 06 871 5000 to discuss and obtain the correct application form.  Alternatively, email the Service Assurance Team on

For fees and charges related to wastewater discharge see the Fees and Charges page.

More information

Uncontrolled trade waste discharge has the potential to have significant negative effects on the sewer system and block screens at the wastewater plant.

Fat and solids can build up in the sewers and cause blockages and overflows, which are costly to clear and clean up, cause nuisance and can be harmful to people and the environment.

Some characteristics, in excessive amounts, can cause the formation of toxic gasses in the sewer system, which is hazardous for people working in or around the sewer network.  Some gasses cause corrosion of the sewers.

If the restriction or blockage is found to be caused by one business, then the discharge from that business is assessed and appropriate pre-treatment options or remedies will be recommended.  The remedies or pre-treatment will at the business expense. 

All holders of an Approval to Discharge Controlled Wastewater must take regular samples of their discharge.  The samples are analysed by an approved laboratory and the results sent to Council’s Trade Waste Officer for reviewing.  The Trade Waste Officer also does random monitoring of discharges to check if they are within approved limits.

The Trade Waste Officer also carries out random inspections of permitted discharges and investigates when reports are received of blockages or other issues, from Council contractors who do maintenance work on the sewers.


Table A

Flow Rate 1 litre per second
Volume per day (24 Hours) 10,000 litres
Suspended Solids 2000 grams per 1000 litres
Settleable Solids 50 ml per litre
Total Oil and Grease 100 grams per 1000 litres
Petroleum Hydrocarbon 30 grams per 1000 litres
pH Must be greater than 6.0

These are the most common characteristics only, the full schedule of limits from the Bylaw is included at the end in “Schedule B to Chapter 7 of the HDC Consolidated Bylaw”.

The nature of some industries means the wastewater from them contains characteristics that are more than what is allowed to be discharged.  Those characteristics can be reduced by putting pre-treatment in place.  Some will require an approval to discharge even after pre-treating their wastewater but some may, by having pre-treatment in place, bring their discharge characteristics from being controlled wastewater to being a permitted discharge.  See Table B for more information.


Takeaway shops, Bakeries, Cafes, Restaurants, Dairys that sell food cooked on the premises (e.g., Kool’s Chicken) Supermarkets Oil and Grease. Grease Trap or alternative grease removal system. See sizes needed in Table C. Usually considered to be Permitted discharge unless any of the characteristics in Table A are not met after pre-treatment.
Mechanical workshops, Car and Truck Wash  Petroleum Hydrocarbons. Solids. Oil and Grit Interceptor Usually considered to be Permitted discharge with correctly sized interceptor and meet flow rate and volume limits.
Laundromats Solids. Screens to remove lint and solids Usually considered to be Permitted discharge if flow rate and volume limits are met.
 Dentist  Amalgam from fillings. Amalgam Trap Usually considered to be Permitted discharge.
Butcher shops – with no cooking on site           Solids. Ensure trimmings do not get into the discharge (screens) Usually considered to be Permitted discharge.
Small Breweries Brewing process typically results in low pH effluent. pH adjustment Usually considered to be Permitted discharge unless any of the characteristics in Table A are not met after pre-treatment.
Large Breweries and Wineries Brewing process typically results in low pH effluent. Solids. pH adjustment – settling - screening Yes - Approval needed.
Canneries, Food Processing, Juicing Processors, Meatworks, Fellmongeries, Tanneries  Varies between types of industries and includes Solids. Oil and Grease. Sulphide. Amonical N. Chromium III.pH. Various pre-treatment including; Screening DAF Settling Oxidation pH adjustment Yes - Approval needed.

Food related businesses e.g. takeaway shops, restaurants, butcher shops, cafes, bakeries, in fact any business that processes food on the premises are likely to discharge oil and grease (fat) into the wastewater network. If oil and grease is discharged in excessive amounts it can solidify and cause sewer blockages, resulting in overflows, hazards to public health and pollution of the environment.

The most common method of pre-treatment for these types of businesses is a grease trap.

The most preferred grease trap design is simple non mechanical device (passive grease trap) that captures the oil and grease that is present in the wastewater generated by the business.  Grease Traps are made from concrete, stainless steel or plastic. Concrete traps are generally installed in the ground, stainless steel and plastic traps are often installed above ground. Some manufacturers offer custom made plastic traps that can be fitted into awkwardly shaped spaces.

There are some alternative grease removal systems available, these are mechanical systems, commonly referred to as under bench grease removal system.  It is important that the system is correctly sized for the discharge flow rate and volume and operated according to the manufacturers instructions. Discharge from the system must meet the 100 mg/L Bylaw limit.

Installing a passive grease trap or another type of grease removal system that is too small for the flow rate or volume of wastewater is likely to result in a significant amount of the oil and grease flowing through the system and entering the wastewater system, resulting in a discharge that does not comply with the Bylaw.

For any new or replacement installations, the enzyme-based digester/converter type grease removal systems are no longer approved for use by HDC from 31 December 2023.

Council recommends the following passive grease trap sizes, based on actual sampling results from various businesses in Hastings and results from various studies of grease traps in New Zealand and Australia.

Table C

Takeaway premises, cafes, bakeries etc 1000L
Restaurants serving up to 70 meals per day 1000L
Restaurants serving between 70 and 200 meals per day 1500L
Restaurants serving between 200 and 400 meals per day 2000L
Supermarkets 3000L

Yes. Regular emptying and cleaning are critical to correct and effective operation of the systems.

Some businesses engage a contractor to empty and clean the trap on a regular schedule.  The frequency can be established with the contractor based on observation of the condition of the trap over a period or by monitoring the grease trap to establish when it needs cleaning. The frequency of cleaning will vary based on the size of the trap and the amount of oil and grease generated by the business but, as a rule, when approximately quarter of the working depth of the trap is taken up by the layer of solids on the bottom and the floating oil and grease layer, the trap should be emptied. Once the trap has been emptied and cleaned it should be filled with cold water to ensure proper operation. At the time of cleaning the trap should be checked for any faults.

For alternative grease removal systems, the manufacturers' and installers' instructions must be followed to ensure proper operation of the system.  The oil/grease skimmed off by the system must be decanted into a recycling waste oil drum.  Under no circumstances should it be tipped into a toilet, sink or a gully trap.

The trap stops working as it is designed to do and, in some cases, will block and cause overflow on the premises.  In other cases, it will still allow the wastewater to flow through untreated. The discharge of excess oil or grease may result in a blocked sewer.  This would be a breach of the Bylaw.

It would be unwise to use a waste grinder as it could seriously reduce the effectiveness of any grease removal system in use.  Solids would build up in the grease trap or the alternative grease removal system, which reduces the effectiveness of the system and can result in anaerobic conditions in the system, causing it to emit foul smells.

Using waste grinders could also cause the discharge to exceed the solids limits in the Bylaw.

These types of businesses will have oil, lubricants and fuel that gets washed off mechanical parts, equipment or vehicles, or sometimes small spills happen.  Oil and fuel are referred to as petroleum hydrocarbons in Schedule B in the Bylaw.  The most common pre-treatment for wastewater from these types of businesses is an oil and grit interceptor.  The oil floats to the top and the grit, that is washed off vehicles, settles to the bottom of the interceptor.  The interceptor must be of the right size for each situation, and it must be maintained regularly to ensure it works properly.


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