Grease Trap Installation Guide for Melbourne Businesses

Planning a Grease Trap Installation in Melbourne

Installing a grease trap is a significant investment for any Melbourne food business — and one that requires careful planning, the right approvals, and qualified tradespeople. Whether you are fitting out a new commercial kitchen, upgrading an existing system, or responding to a compliance notice from Melbourne Water, this guide walks you through the entire process from initial planning to commissioning.

Step 1: Determine Your Requirements

Before selecting a trap or engaging a plumber, you need to understand what your business actually requires. Several factors drive this:

Trade waste consent: If you already hold a trade waste agreement with Melbourne Water, it will specify minimum trap size, type and maintenance frequency. If you do not have one, you will need to apply before installation.
Business type and FOG output: A high-volume restaurant generates far more fats, oils and grease than a small cafe. Your trap must be sized accordingly.
Available space: In-ground traps need excavation area and ongoing vehicle access for pump-outs. Above-ground units and AGRUs need internal floor space.
Budget: Costs vary significantly by trap type, size and site conditions.

Our detailed grease trap sizing guide explains how to calculate the correct capacity using the AS 1546.1 methodology.

Step 2: Engage a Licensed Plumber

In Victoria, all grease trap installations must be carried out by a licensed plumber who holds the appropriate registration with the Victorian Building Authority (VBA). This is a legal requirement — unlicensed installation is an offence and will void any compliance certification.

What to Look for in a Plumber

Current VBA plumbing registration
Specific experience with commercial grease trap installations
Familiarity with Melbourne Water trade waste requirements
Willingness to handle the permit and approval process
Insurance coverage for commercial plumbing work

Your plumber will prepare the installation design, including pipe sizing, fall gradients, trap location and ventilation — all of which must comply with AS/NZS 3500 (Plumbing and Drainage) and AS 4674 (Construction and Fitout of Food Premises).

Step 3: Obtain Approvals and Permits

Grease trap installation in Melbourne typically requires multiple approvals:

Melbourne Water Trade Waste Consent

All commercial food businesses discharging to Melbourne’s sewer system need a trade waste consent from Melbourne Water. This consent specifies the type and size of grease trap required, acceptable discharge limits and maintenance obligations. If you are a new business, apply well in advance — processing can take 4 to 8 weeks.

Council Building Permit

For in-ground installations, a building permit from your local council may be required, particularly if the work involves excavation, structural modifications or changes to the building’s drainage system. Your plumber or building surveyor can advise on whether a permit is needed.

Plumbing Compliance Certificate

After installation, your plumber must submit a compliance certificate to the VBA and your local council, confirming the work meets all regulatory requirements. This is a mandatory step — without it, the installation is not legally compliant.

Step 4: Site Preparation

The extent of site preparation depends on the trap type:

In-Ground Trap Preparation

Excavation of the pit to required dimensions (depth, width and length per trap specifications)
Preparation of a compacted base — often a concrete pad for heavy traps
Routing of drainage pipes from kitchen fixtures to the trap location
Ensuring vehicle access for future pump-out trucks (minimum 3-metre-wide path)
Managing soil and spoil disposal — your plumber or contractor should arrange this

Above-Ground Trap Preparation

Clearing the installation area inside the kitchen
Ensuring the floor can support the weight of a full trap
Providing drainage connections from relevant fixtures
Ensuring adequate ventilation to manage potential odours

Step 5: Installation

Professional grease trap installation typically follows this sequence:

Positioning and levelling the trap unit
Connecting inlet pipes from kitchen drainage fixtures
Connecting the outlet pipe to the sewer line
Installing access lids and ensuring they are sealed and secure
Testing for leaks with a water fill test
Backfilling and compacting around in-ground traps
Installing any required ventilation or sampling points

For in-ground traps, the process typically takes 2 to 5 days. Above-ground installations can often be completed in a single day.

Step 6: Commissioning and Inspection

Once installed, the trap must be commissioned and inspected:

Your plumber conducts a final inspection and issues a compliance certificate
Melbourne Water may inspect the installation as part of your trade waste consent activation
The trap is filled with clean water to establish the initial water seal
Maintenance schedules are set based on your consent conditions

Timeline and Cost Expectations

Typical Timeline

Trade waste consent application: 4 to 8 weeks
Plumber engagement and design: 1 to 2 weeks
Council permit (if required): 2 to 4 weeks
Installation: 1 to 5 days
Total from start to commissioning: 8 to 16 weeks

Cost Ranges for Melbourne

Above-ground trap (installed): $800 to $4,000
In-ground trap 1,000L (installed): $4,000 to $8,000
In-ground trap 2,000-5,000L (installed): $8,000 to $20,000+
AGRU (installed): $8,000 to $25,000

These figures include the trap unit, excavation (where applicable), plumbing, backfill and compliance certification. Complex sites — such as those requiring rock excavation, deep trenching or structural modifications — will be at the higher end.

Compliance with Melbourne Regulations

A properly installed grease trap must comply with:

AS 1546.1 — sizing requirements
AS/NZS 3500 — plumbing and drainage standards
AS 4674 — food premises construction and fitout
Melbourne Water trade waste consent conditions
EPA Victoria — Environment Protection Act 2017 general environmental duty
Local council building regulations

Ready to Install?

Our team manages grease trap installations across Melbourne — from initial sizing and design through to commissioning and ongoing maintenance. We work with experienced licensed plumbers and handle the approval process on your behalf. Contact us today for a free installation quote tailored to your business.