If you cook in a cafe, restaurant, takeaway or club on the Central Coast or in Lake Macquarie, greasy kitchen wastewater is trade waste. It cannot go straight to sewer. You need a grease trap (the water authorities call it a grease arrestor) and written approval from the local water authority before that discharge starts. A licensed plumber sizes and installs the trap to that authority’s requirements; a licensed or accredited contractor pumps it out.
TL;DR
A grease trap holds kitchen wastewater long enough for fat and solids to separate so they do not coat the sewer. Food businesses that generate greasy waste need one, plus trade-waste approval from Hunter Water in Lake Macquarie and Newcastle, or Central Coast Council on the Coast. Hunter Water recognises arrestors from 1,000 litres to 5,000 litres. Pump-out is by an accredited contractor, then the trap is refilled with clean water.
What is a grease trap, and who needs one?
A grease trap (grease arrestor) is a tank on the kitchen drain. Wastewater sits in it long enough for fat, oil and grease to float and food solids to sink. The clearer water in the middle is what leaves the property. Sinks, dishwashers, pot-wash and kitchen floor waste feed it. Hand basins, showers and toilets do not: that is domestic sewage, not trade waste.
Hunter Water treats any liquid waste from a non-residential property as trade wastewater, and only accepts discharge that complies with its guidelines. Central Coast Council treats liquid waste from a business as liquid trade waste, and lists cafes, restaurants, hotels, motels, butchers and supermarkets among the typical sources. Council’s page says you must pre-treat that waste and install and maintain the required treatment equipment, “e.g. grease traps”.
If the kitchen generates greasy or oily wastewater, expect a grease arrestor and an approval. Council has a Category 2 form for food businesses that generate greasy or oily waste, and a separate Category 1 form for food businesses that do not. Check with the authority rather than guessing from the shop next door.
Which water authority approves the discharge?
Lake Macquarie and Newcastle sites are Hunter Water. Their trade waste page is the starting point: an application and deed set the terms under which they will accept the discharge.
Central Coast suburbs are Central Coast Council water and sewer. Businesses proposing to discharge liquid trade waste to a Council sewer must obtain prior approval. Apply before you open or change the kitchen; the assessment can take time and may include an inspection. Applications go in from the property owner, or from a tenant with the owner’s consent. Council’s liquid trade waste page sets that out, including the Category 2 form for greasy food businesses. Approvals last five years and then need a new application.
Do not plumb the trap in first and apply afterwards.
Central Coast Council and Hunter Water run separate systems, so here is how they compare on approval, pump-out and who to contact:
| Requirement | Central Coast Council | Hunter Water |
|---|---|---|
| Area | Central Coast suburbs | Lake Macquarie and Newcastle |
| Approval needed | Prior approval before discharge starts, via the Category 2 form for greasy waste | Application and deed for discharge; new or upgraded trap needs a portal application |
| Pump-out/service frequency | Set in your approval; licensed contractors only | Set in your approval; accredited contractor refills with clean water |
| Who to contact | Council’s liquid trade waste page | plumbing@hunterwater.com.au |
Who sizes and installs the trap?
Hunter Water’s pre-treatment requirements say they recognise grease arrestors sized 1,000 litres minimum and 5,000 litres maximum. New work needs a hydraulic design assessment through their portal. An extra trap, or an upgrade on an existing site, needs a facility upgrade application.
Central Coast Council does not publish a single litre figure on its liquid trade waste page. The required equipment comes through the approval for that site. Do not copy a Hunter Water litre range onto a Central Coast kitchen.
Installation is licensed plumbing and drainage, done to the details the authority has accepted. Kitchen sinks, dishwashers and floor waste that feed the trap sit with the rest of the kitchen plumbing. Commercial sites that cook often need backflow testing on the same property as well, lodged with the same water authority.
What pump-out and maintenance is required?
Neither Hunter Water nor Central Coast Council puts a single pump-out interval on the pages above. The interval sits in your approval.
Council says use licensed contractors where waste has to be removed. Hunter Water says after an accredited contractor has cleaned the pre-treatment facility out, refill it with clean water so it operates properly again. Running a just-pumped trap empty puts it straight back into non-compliance.
Hunter Water also tells kitchens not to pour oil, grease or fats down the sink (recycle spent cooking oil) and to bin food scraps rather than wash them into the trap. A trap that is pumped on schedule but still fed with fryer oil will not stay compliant.
What goes wrong if the trap is undersized or neglected?
A trap that is too small does not hold the peak kitchen flow long enough for grease to separate. Hunter Water will not recognise an arrestor outside the 1,000 to 5,000 litre range. Grease then rides through into the kitchen drain and the sewer.
A trap that is not pumped fills with a grease mat on top and sludge on the bottom until wastewater short-circuits through the middle. That is how a kitchen line keeps blocking in the same spot, and how fat reaches the authority’s pipes. Hunter Water only accepts trade wastewater that complies with its guidelines. Council manages trade waste to protect the sewer, the environment and public health.
If the menu, seating or dishwashers have grown since the trap went in, another pump-out will not fix the size. That is an upgrade application, then a licensed plumber to install what the authority will actually accept.
If you are opening a kitchen, or an existing trap is backing up, request a callback. Donza’s commercial plumbing covers grease-trap work for food-prep sites across the Central Coast and Lake Macquarie.