How Often Should You Clean a Grease Trap? Start With Your Trade Waste Agreement

There is no single right answer, but most commercial kitchens fall somewhere between monthly and quarterly. The exact figure for your kitchen is not a rule of thumb. A trade waste agreement with your local water authority sets it, based on your trap size and how much fat, oil and grease your kitchen actually produces. If you do not know that number, find it out first. The pump-out frequency comes second.

What is a trade waste agreement and why does it set the schedule?

A trade waste agreement is a contract between your business and your water authority that governs what you can discharge into the sewer, including fat, oil and grease. Sydney Water's trade waste program issues these agreements when a grease trap or interceptor is installed, and they specify a required cleaning or pump-out interval alongside discharge limits.

Many operators inherit a kitchen, a lease, or a business without ever seeing this document. Grease Trap Compliance NSW: Rules, Frequency and Fines walks through where NSW operators can find theirs, and what happens if the interval on paper does not match what actually happens in the kitchen. The agreement, not a generic industry guideline, is the number an inspector checks against.

What pushes your frequency above or below the average?

Four things move the number for a given kitchen: trap size relative to cooking volume, how greasy the menu is, how consistent daily covers are, and how much slack the water authority builds into the agreement. A large-format trap serving a low-volume cafe runs longer between services than a small trap under a high-output fryer line, even though both might sit in the same one-to-three-month range on paper.

Seasonal swings matter too. A kitchen that doubles its covers over summer or during a local event calendar fills a trap faster than its default schedule assumes. Flag that to your cleaner rather than waiting for the next scheduled date to arrive.

What actually happens if the trap runs past its interval?

A trap holding more fat, oil and grease than its rated capacity starts letting grease pass through into the sewer line, which is the exact outcome the agreement exists to prevent. Before that, most kitchens get an earlier warning. Slow drains near the trap. A sour smell around the kitchen or loading area. A trap lid that will not seat properly because it is packed full.

Running past the agreed interval is also a common compliance failure water authorities and councils flag on inspection. Grease Trap Compliance ACT: Rules, Frequency and Fines and Grease Trap Compliance NT: Rules, Frequency and Fines cover what an inspector checks and what a missed pump-out costs in fines, by jurisdiction. The NSW EPA's guidance on trade waste and sewer blockages sets out why FOG discharge is treated as an environmental issue, not just a plumbing one.

Why does the price vary so much between kitchens on a similar schedule?

Two kitchens on the same monthly interval get different quotes, because cleaners price the job on trap size, service frequency, how accessible the trap is for the pump truck, and disposal fees for the waste collected. A trap in a tight rear laneway with limited truck access costs more to service than one with a clear driveway, whatever the grease load inside it.

That is why comparing quotes matters more than comparing a single headline number. Grease Trap Cleaning: How Often Should a Grease Trap Be Cleaned? covers the general frequency ranges by kitchen type in more depth if you are still narrowing down where your kitchen sits on that scale.

What should you actually do if you don't know your schedule?

Check your trade waste agreement first. If you cannot locate one, contact your water authority directly rather than guessing at a generic interval. WaterNSW and your local council trade waste team can both point you to the right contact if Sydney Water is not your provider. In our experience, most operators only think about the trap when it smells, backs up, or an inspection is already on the calendar, which is the most expensive time to work it out.

Once you know the interval you need, get 3 grease trap quotes from licensed cleaners. We send three by SMS, usually within about a minute of the request, so you can compare price and availability against your actual schedule instead of booking the first number you find. The service currently covers Sydney and is expanding to other Australian cities.

If you run a licensed cleaning business and want jobs from kitchens working out their schedule like this, you can apply to join GreaseTrapQuotes as a licensed contractor, and see contractor territory pricing for how territories are structured.

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*Written by Mario Lucas. Mario runs Grease Trap Quotes, which matches commercial kitchens in Sydney with licensed grease trap cleaners.*

Related reading: Grease Trap Installation: The 8-Step Checklist Before You Sign Off on a New System.