New Grease Trap Installation: The 9-Item Checklist Before You Call a Plumber

Most kitchens end up with whichever grease trap the plumber had on the truck, not the size the site actually needs. That one shortcut costs you twice. Once on the install, and again every time a cleaner turns up and can't service a trap that was never right for your volume.

Work through this checklist in order before you call anyone. It is the sequence that avoids a redo.

1. Confirm your trade waste agreement before you size anything

Your water authority sets the terms your new trap has to meet, including where it can sit and how it gets serviced, through a trade waste agreement. Many operators do not know theirs exists until an inspector asks for it. Check with your local water authority, such as Sydney Water's trade wastewater requirements, before you choose a trap or a location.

• Ask your water authority directly if you do not have a copy on file
• Note any minimum trap size or capacity stated in the agreement
• Check whether the agreement specifies pump-out frequency, since that affects access planning later in this list

2. Size the trap to your kitchen's actual flow, not its floor space

A cafe with a small footprint but a full espresso and wash-up line can produce more wastewater than a larger kitchen doing mostly plating. Sizing runs off fixture count, flow rate and food type, not square metres. Sydney Water's guidance on selecting and installing a grease trap sets out the method authorities expect installers to follow.

3. Decide where it sits before you decide what to buy

Location drives both cost and every future service call. An underground trap outside costs more to install but keeps it out of the kitchen. An indoor under-sink unit is cheaper upfront, but it limits capacity and puts a cleaner in your service area during business hours.

• Underground, outside: higher install cost, easier long-term access for pump trucks
• Indoor, under-sink: lower install cost, smaller capacity, disrupts kitchen flow at service time
• Check clearance for a vacuum hose to reach the trap from wherever the truck can park

4. Plan access for the cleaner, not just the plumber

Installers skip this one most often, and it is the one that quietly inflates every service bill afterwards. A trap sitting behind a locked storeroom, under a fixed bench, or more than a short hose-run from legal parking costs more to clean every single time, for the life of the trap. Water Corporation's grease arrestor installation guidelines cover access and venting requirements directly.

• Walk the route a cleaner's hose would take from truck to trap
• Confirm there is legal, unrestricted parking for a pump truck at service times
• Avoid locating the trap behind anything that needs a key held by someone who isn't always on site

5. Get the venting right the first time

A grease trap needs proper venting to avoid odour and pressure problems. Retrofitting vent work after the concrete is poured or the slab is cut costs far more than specifying it upfront. Confirm your plumber has priced venting into the initial quote, not as a variation later.

6. Ask what disposal fees you'll be charged, and where the waste goes

Cleaners quote on trap size, service frequency, access, and disposal fees. So a well-sized, well-placed trap can still end up expensive if you never asked about the disposal side. Ask upfront where the licensed waste is taken and whether that cost is fixed or variable. Most installation guides stop at the plumbing and never follow the waste past the truck, which is why almost nobody explains this part.

7. Set your pump-out frequency from the agreement, not from guesswork

Once the trap is in, your trade waste agreement (see item 1) determines how often it legally needs pumping. Most operators only think about their trap when it smells, backs up, or an inspection is due. That is exactly the pattern that leads to missed pump-outs and failed checks. Lock the frequency in against the agreement, not against how busy the kitchen feels that month.

8. Get the quote in writing with size, access and frequency spelled out

A verbal quote that only mentions a dollar figure hides the variables that actually set the price. A written quote should state trap size, expected service frequency, access conditions and disposal handling, so you can compare it against a second opinion on the same terms.

• Trap size and expected capacity
• Service frequency assumed in the price
• Access conditions noted by the installer
• Disposal fee structure, fixed or variable

9. Line up your first cleaner before the trap is even finished

A new installation with no cleaner booked is how traps sit unserviced for months. Grease Trap Quotes sends three quotes from licensed cleaners by SMS, usually within about a minute of the request, so you can have a servicing contractor lined up before the plumber has packed up the van. If you're weighing up whether to handle interim maintenance yourself, our piece on whether you can clean a grease trap yourself or need a professional covers the difference for a freshly installed trap.

A new trap is only as good as the plan around it. Get three quotes from licensed cleaners at Grease Trap Quotes before your install is finished, so day one of operation starts with a service schedule already locked in, not worked out after the first complaint.

If you're a licensed cleaner or plumber who wants to be one of the contractors quoting on new installations like these, you can apply to join GreaseTrapQuotes and see contractor territory pricing for your area. Read more on our blog or learn about how GreaseTrapQuotes works.

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Related reading: Grease Trap Cleaning in Wendouree: How Often Victorian Kitchens Actually Need It.

Related reading: Grease Trap Servicing in Sydney: A Practical Guide for Kitchen Owners.