Control Kitchen Fats & Oils Before Your Septic Tank

Where do cooking fats & oils go once they disappear down the kitchen sink? On properties using septic systems, those residues can add unwanted load downstream. RELN grease traps are designed for domestic effluent disposal, intercepting fats & oils from kitchen wastewater before they reach the septic tank. Explore the broader RELN range when planning the surrounding wastewater, drainage & property setup.

Think of the trap as a checkpoint between the kitchen & the septic system. RELN's 18L Grease Trap connects with suitable 100mm wastewater pipework, providing a dedicated interception point before effluent continues downstream. Where the property also requires broader drainage infrastructure, RELN | Drainage & Pits provides a useful companion range.

Easy access today can save an awkward maintenance job tomorrow. Because collected grease needs regular removal, RELN recommends installing the unit at ground level in a safe, non-traffic area where the lid remains accessible for cleaning.

What Are RELN | Grease Traps?

RELN grease traps are domestic wastewater fittings designed to reduce fats & oils entering septic tanks from kitchen sinks. Wastewater passes through the trap before continuing towards the septic system, allowing grease to be intercepted earlier in the wastewater route.

RELN's 18L Grease Trap features:

► 18L capacity
► 100mm inlet socket
► 100mm outlet spigot
► Suitability for 100mm AS/NZS 1260 DWV uPVC pipe
► Three internal baffles
► 30mm invert fall
► Heavy-duty 10mm-thick walls
► Removable lid
► Separately identified lid, baffle & bin components

Inside the unit, three baffles form part of the designed wastewater path. With an approximate footprint of 480mm x 260mm plus a height around 350mm, the trap is compact enough for domestic applications while still requiring adequate room for connections & servicing.

Accurate positioning becomes easier when pipe routes, clearances & levels are established with suitable Measuring & Layout Tools.

Why Choose RELN | Grease Traps?

Sending unnecessary grease towards a septic tank gives the system more to deal with. RELN explains that fats & oils increase biological load within the tank, reducing the ability of anaerobic bacteria to digest effluent sludge effectively.

A correctly selected RELN grease trap can help:

► Intercept kitchen fats upstream
► Reduce oils entering the septic tank
► Support domestic septic wastewater management
► Provide an accessible point for grease removal
► Connect with suitable 100mm DWV uPVC pipework
► Reduce fats & oils travelling further downstream
► Allow individual components to be replaced where suitable
► Make regular servicing more practical
► Support a planned domestic effluent-disposal arrangement

Downstream performance gives grease interception an even stronger purpose. RELN identifies fats & oils overflowing into evapo-transpiration trenches as a major cause of trench-system failure, making upstream grease control particularly relevant on properties relying on septic effluent disposal.

Where installation involves excavation, pipe preparation or surrounding construction work, Commercial Construction provides equipment for the broader job.

Common Applications

Does the property rely on a septic tank rather than a conventional sewer connection? That's the key setting for RELN's domestic grease-trap application.

► Homes with septic tanks – intercept kitchen fats & oils before wastewater reaches the septic system.
► Rural residences – support domestic wastewater arrangements on properties using septic infrastructure.
► Country properties – create an accessible grease-interception point along the kitchen wastewater route.
► Septic-system installations – incorporate grease interception where suitable for the approved wastewater arrangement.
► Replacement projects – replace an existing compatible domestic grease trap where required.
► Kitchen wastewater lines – reduce the amount of grease travelling downstream from sinks.
► Effluent-disposal systems – help limit fats & oils reaching later stages of septic wastewater disposal.
► Property maintenance – maintain an accessible point where accumulated grease can be removed.

Unlike a stormwater pit, this unit has a very specific role. RELN designed the Grease Trap around domestic kitchen effluent entering a septic system, so it shouldn't be treated as a general-purpose drainage container or stormwater fitting.

Product Selection Guide

Start With the Wastewater Route

Before measuring the trap, follow the kitchen wastewater from the sink towards its destination.

Check:

► Whether the property uses a septic system
► Kitchen waste-pipe route
► Existing grease interception
► Pipe diameter
► Septic-tank location
► Available installation space
► Future cleaning access
► Applicable wastewater requirements

Seeing the complete route puts the fitting in context. The grease trap needs to sit within a suitable wastewater arrangement between the kitchen discharge line & septic system.

Confirm the 100mm Connection

Pipe compatibility is one detail worth settling before excavation begins.

RELN specifies:

► 100mm inlet socket
► 100mm outlet spigot
► Suitability for 100mm AS/NZS 1260 DWV uPVC pipe

Measure existing pipework before cutting anything. Diameter, alignment, levels plus available connection space should all suit the proposed installation rather than being corrected after the trap is positioned.

Check the Installation Space

Will the unit fit once the pipe connections plus maintenance area are included?

RELN specifies approximately:

► 480mm length
► 260mm width
► 350mm height
► 18L capacity

Physical dimensions are only the starting point. Leave enough surrounding room to access the lid, inspect the trap plus service the connected pipework without unnecessary obstruction.

Put Cleaning Access First

Picture the installation after months of use: can somebody still reach the lid comfortably?

RELN recommends positioning the unit:

► At ground level
► In a safe location
► Away from traffic
► Where cleaning access remains practical
► Between the kitchen wastewater pipework & septic system

Future servicing should influence today's installation position. Landscaping, storage, fencing or permanent structures shouldn't turn a routine clean into an excavation job.

Keep It Away From Traffic

The shortest pipe route isn't necessarily the smartest location if vehicles regularly pass over it.

Avoid areas exposed to:

► Cars
► Utes
► Trailers
► Machinery
► Regular heavy traffic
► Stored equipment
► Future building work

Imagine how the property may change over the life of the installation. Driveways, sheds, paths plus storage areas can move or expand while the wastewater system stays where it was installed.

Understand the Three-Baffle Arrangement

What happens between the inlet & outlet matters just as much as the pipe connections themselves.

RELN's 18L unit incorporates:

► Three internal baffles
► 100mm inlet
► 100mm outlet
► 30mm invert fall

Those baffles belong to the designed internal arrangement. Damaged, incorrectly positioned or missing components deserve attention during servicing rather than being treated as optional parts.

Know the Replacement Components

Cracked lid but serviceable bin? Replacing the complete trap may not always be necessary.

RELN identifies:

► 18L Grease Trap Complete – product code 000914
► 18L Baffle Only – product code 000921
► 18L Lid Only – product code 000945
► 18L Bin Only – product code 000938

Product codes take much of the guesswork out of identifying replacement components. Compare the existing unit carefully before deciding whether an individual part or complete trap is required.

Make Regular Cleaning Part of Ownership

A grease trap succeeds by collecting material you don't want downstream, so eventually that material needs removing.

Routine checks can include:

► Inspecting the lid
► Monitoring grease accumulation
► Checking accessible baffles
► Keeping the surrounding area clear
► Watching wastewater flow
► Investigating unusual odours
► Maintaining safe service access
► Arranging appropriate grease disposal

RELN advises regular cleaning rather than waiting for an obvious wastewater problem. The manufacturer also recommends contacting a local grease-trap disposal company for cleaning.

Reduce Grease Before It Reaches the Trap

The easiest grease for a septic system to manage is the grease that never enters the sink.

Practical kitchen habits can include:

► Wiping greasy cookware before washing
► Keeping cooking oil out of the drain
► Scraping food residue into appropriate waste
► Using suitable sink strainers
► Avoiding unnecessary fats in wastewater
► Following local disposal requirements

Good habits reduce the amount the trap has to collect. Treat grease interception as a safeguard rather than an invitation to deliberately dispose of cooking fats or oils through the kitchen sink.

Investigate Changes in Drainage

Has the kitchen sink started clearing more slowly than usual? A noticeable change in wastewater behaviour is worth investigating rather than waiting for a complete blockage.

Areas to consider include:

► Grease-trap maintenance history
► Internal accumulation
► Pipe restrictions
► Accessible baffles
► Downstream wastewater flow
► Septic-system condition

Resist blaming the first component you can reach. Slow drainage can have several causes, so persistent problems may require investigation across the complete wastewater route.

Useful Hand Tools can support general access, fitting plus property-maintenance work around the installation.

Keep the Lid Easy to Find

Out of sight is useful; forgotten beneath landscaping isn't.

After installation:

► Keep the location identifiable
► Avoid permanently covering the lid
► Prevent excessive soil build-up
► Keep stored materials away
► Maintain working space
► Check lid condition periodically

Recording the location can save considerable searching years later. That's particularly useful on larger rural properties or where landscaping, buildings or ownership may change.

Look Beyond the Grease Trap

One well-maintained fitting can't compensate for problems elsewhere in the septic system.

The wider wastewater arrangement can include:

► Septic tank
► Connecting pipework
► Effluent disposal
► Distribution components
► Evapo-transpiration trenches
► Property-specific wastewater infrastructure

Treat grease interception as one part of broader septic care. Downstream components still need to remain suitable, serviceable plus maintained according to the requirements applying to the property.

Protect the Installation During Nearby Work

Renovations have an unfortunate habit of finding buried services after machinery arrives.

Before excavation, landscaping or construction nearby:

► Identify the grease-trap location
► Identify connecting pipework
► Protect the lid
► Keep vehicles away
► Prevent debris entering the unit
► Preserve cleaning access
► Inspect the area after work finishes

Appropriate Safety & PPE should be selected for excavation, wastewater maintenance plus the conditions encountered around the installation.

Expert Tips

► Trace the wastewater route first. Know how kitchen discharge reaches the septic system before choosing the installation point
► Confirm the 100mm pipework. RELN specifies a 100mm inlet socket plus 100mm outlet spigot.
► Allow service space. The physical footprint isn't the only room the installation needs.
► Follow the ground-level recommendation. Accessible placement makes regular cleaning considerably easier.
► Choose a non-traffic location. Keep the unit away from vehicle plus machinery movement.
► Protect the three baffles. They form part of the designed internal wastewater path.
► Keep cooking oil out of the sink. Reducing grease at the source means less accumulation inside the trap.
► Make the lid easy to locate. Future servicing shouldn't require rediscovering the installation.
► Clean regularly. Trapped fats & oils need appropriate removal.
► Arrange suitable disposal. RELN recommends contacting a local grease-trap disposal company for cleaning.
► Investigate slow drainage. Changing flow can indicate maintenance or wider wastewater issues.
► Use RELN product codes. Separate lid, baffle plus bin components are identified for the 18L unit.
► Protect the system during renovations. Nearby excavation can affect both the trap plus connecting pipework.
► Remember what comes next. The septic tank plus downstream effluent-disposal system still require appropriate care.