Types of Grease Traps: Complete Guide for Melbourne Businesses

Understanding the Different Types of Grease Traps for Melbourne Commercial Kitchens

Every commercial kitchen in Melbourne that discharges trade waste into the sewer system is required to install an approved grease trap or grease interceptor. But with multiple types available — each with distinct advantages, limitations and ideal applications — choosing the right system can feel overwhelming. This comprehensive guide breaks down every grease trap type used across Melbourne, helping you make an informed decision that satisfies both regulatory requirements and operational needs.

Whether you operate a busy restaurant in the CBD, a cafe in Fitzroy, or a food manufacturing facility in the western suburbs, understanding your options is the first step toward compliance with EPA Victoria trade waste regulations and Melbourne Water consent conditions.

In-Ground Grease Traps

In-ground grease traps are the most common type installed across Melbourne’s commercial food sector. Buried beneath the ground — typically outside the kitchen near the drainage connection — these units rely on gravity separation to intercept fats, oils and grease (FOG) before wastewater enters the sewer.

How They Work

Wastewater flows into the trap’s chamber, where it slows down. Because FOG is lighter than water, it floats to the surface and is retained in the trap while cleaner water exits through a submerged outlet. Over time, solids settle to the bottom as sludge, and the grease layer accumulates on top — both requiring periodic pump-out and cleaning.

Typical Capacities

In-ground traps in Melbourne range from 1,000 litres for small cafes up to 5,000 litres or more for large restaurants, hotels and food courts. Sizing must comply with AS 1546.1 and is typically calculated based on fixture units and peak flow rates. For help determining your needs, try our grease trap size calculator.

Best Suited For

• Restaurants, cafes and takeaway shops with moderate to high FOG output
• Premises with available outdoor space for installation
• Businesses seeking a cost-effective, proven solution

For a detailed side-by-side comparison, read our article on in-ground vs above-ground grease traps.

Above-Ground Grease Traps

Above-ground grease traps operate on the same gravity separation principle but are installed inside the kitchen — typically under a sink or on a nearby wall. They are smaller, ranging from 20 to 200 litres, and are designed for lower-volume applications or where in-ground installation is not feasible.

Advantages

• No excavation required — ideal for leased premises or heritage buildings in inner Melbourne
• Easy visual inspection and more frequent manual cleaning
• Lower upfront installation cost

Limitations

• Smaller capacity means more frequent maintenance
• Takes up kitchen floor space
• May produce odours if not maintained regularly

Automatic Grease Removal Units (AGRUs)

Automatic grease removal units represent the most advanced grease management technology available to Melbourne businesses. Unlike passive traps, AGRUs use mechanical skimming, heating elements and timers to automatically separate and collect grease into an external container — often on a daily cycle.

AGRUs are increasingly popular in high-end Melbourne restaurants, hotels and institutional kitchens where consistent performance, reduced odour and lower maintenance labour are priorities. They comply with AS 4674 and are accepted by Melbourne Water as an alternative to traditional traps in many circumstances.

We explore these units in depth in our article on AGRU pros, cons and Melbourne applications.

Triple Interceptor Traps (Three-Chamber Systems)

Triple interceptors — also called three-chamber grease traps — feature three sequential separation chambers. Wastewater passes through each chamber progressively, with FOG and solids being captured at each stage. This multi-stage process delivers significantly higher grease removal efficiency than single-chamber designs.

These systems are commonly specified for larger Melbourne venues such as food courts, hotel kitchens, hospitals and aged care facilities. They are particularly effective where high volumes of FOG are generated. Read our detailed comparison in triple interceptor vs standard grease trap.

Passive Gravity Grease Traps

Passive gravity traps are the simplest and most traditional design. They rely entirely on the natural buoyancy of grease and the settling of solids — with no moving parts, no power supply and no automation. Both in-ground and above-ground traps can be classified as passive gravity systems.

Key Characteristics

• No electricity or mechanical components required
• Low purchase and installation cost
• Reliable but dependent on regular scheduled pump-outs
• Performance declines as grease accumulates between services

How to Choose the Right Grease Trap Type

Selecting the correct grease trap for your Melbourne business depends on several factors:

• FOG output volume — Higher volumes demand larger capacity or more efficient systems
• Available space — In-ground traps need excavation area; above-ground and AGRUs fit inside
• Budget — Passive traps cost less upfront; AGRUs save on ongoing maintenance
• Regulatory requirements — Melbourne Water trade waste agreements specify minimum trap sizes and types
• Maintenance preferences — AGRUs reduce manual intervention; passive traps need regular pump-outs

Our team services all grease trap types across Melbourne. Whether you need advice on a new installation, want to upgrade your existing system, or simply need reliable cleaning and maintenance, we are here to help. Contact us today for a free consultation tailored to your business.