Grease Trap Servicing: Find Out How Often You Must Book, Then Test It Against Your Kitchen

This guide is for owners and managers of commercial kitchens in Australia: restaurants, cafes, pubs, clubs, takeaways and food court tenancies. By the end you will be able to decide three things. How often your trap must be serviced. Whether that schedule suits your kitchen. And what to tell a cleaner when you ask for a quote.

Most advice on grease trap servicing explains what the job involves. This guide starts one step earlier, with the question that sets your costs for the year. How often?

Two numbers, not one

Every kitchen has two frequencies, and they rarely match.

The first is the required frequency. Your water authority or council sets this minimum, usually in a trade waste agreement or approval. A quiet month does not let you negotiate it down.

The second is the real fill rate. This is how quickly your trap collects fat, oil, grease and food solids in your kitchen, with your menu, your volume and your habits at the sink.

When the real fill rate is slower than the requirement, you service on the required schedule and the trap has room to spare. When it is faster, you have a problem the schedule hides. The trap fills before the truck arrives. That is when the smell, the slow drain and the backup start.

Most operators only think about the trap when it smells, backs up, or a council or Sydney Water inspection is due. So most kitchens never compare these two numbers until something goes wrong.

Step one: find your required frequency

A trade waste agreement with the water authority sets the pump-out frequency for a commercial kitchen. Many operators do not know theirs. Look in this order.

Check your own paperwork first

Look for a trade waste agreement, approval or consent letter. If you bought the business, the previous owner may have left it in a compliance folder, or your landlord or agent may hold it. Our guide on who sets the grease trap rules in Australia explains why the rule changes depending on where your kitchen is.

Then ask the authority

If you cannot find the document, contact your water authority. In Sydney that is Sydney Water, which runs a trade waste program for businesses. In Western Australia it is the Water Corporation, which publishes its own grease arrestor cleaning and maintenance guidance. Other states have their own authorities, and in some areas the local council sets the rules instead. Ask for the frequency that applies to your address and your type of trap.

Write the answer down

Record the frequency, the date you confirmed it and who confirmed it. You will need this line again when you compare quotes and when an inspector asks.

If nobody can give you a frequency, do not guess a long interval. Ask your cleaner what they apply to similar kitchens nearby. Treat that as a temporary schedule until the authority answers.

Step two: measure your real fill rate

You need no tools. You need two or three checks between cleans and a note of what you saw.

On the day of a clean, ask the cleaner how full the trap was when they opened it. A licensed cleaner sees this on every visit. Then, at the midpoint of your next interval, have a staff member or your cleaner lift the lid and report whether the surface layer is thin, thick or close to the outlet.

Use plain categories and keep them consistent:

• Light: a thin layer, plenty of room.
• Building: a clear layer, about half the working depth.
• Heavy: close to the outlet, or solids banking up at the inlet.
• Overdue: grease reaching the outlet, or any smell or slow drain.

Three readings across one interval tell you more than any calculator. Our post on what to watch when the lid comes off shows what each sign looks like, so this guide does not repeat it.

Step three: compare the two numbers with a decision rule

You can apply this rule without a specialist.

• If the midpoint check is Light: your required schedule is comfortable. Keep it. Do not cut visits below the required frequency.
• If the midpoint check is Building: the schedule suits you. The trap will be near full at the clean, which is how it should work.
• If the midpoint check is Heavy: the trap will be full before the next visit. Book earlier or add a visit, and tell the cleaner why.
• If you find Overdue at any point: book now, and work out what changed in the kitchen.

A worked example shows the decision. Say your agreement requires a clean every three months, and at the six-week check the trap is Heavy. On paper you are compliant for another six weeks. In practice the trap will be full well before then. Bring the next visit forward and ask the cleaner whether a shorter interval suits this kitchen. You pay for one extra visit. In return you avoid a callout, a smell on a Saturday night and a possible overflow. The paperwork shows you met the minimum, and the log shows you did better than it.

The reverse case happens too. If every midpoint reading is Light, you still cannot stretch the interval yourself. You can ask the authority whether your kitchen qualifies for a different arrangement.

What pushes your fill rate up

When a trap fills faster than it used to, something changed. Check these before you blame the cleaner.

• Menu changes: fried food, rich sauces, slow-cooked meats and dairy-heavy dishes put more fat into the water.
• Trade volume: a busier venue washes more plates, pots and trays. A new lunch service or a function room counts.
• Sink habits: scraping plates into the bin before washing keeps solids out. Skip that step and the trap loads quickly.
• Hot water and detergents: very hot water and strong degreasers can carry grease through the trap in a form that settles further down the pipe.
• New equipment: a combi oven, a new dishwasher or an extra prep sink can send new flows to the same trap.

Our post on why your schedule goes stale when your kitchen changes covers this in more depth. The short version: last year's fill rate only guides this year if the kitchen has stayed the same.

How the answer changes what you ask for

Cleaners quote on trap size, service frequency, access to the trap and disposal fees. Two kitchens with the same trap can get quite different prices as a result. Of those inputs, frequency is the one you control most directly.

When you request quotes, give each cleaner the same facts:

• Required frequency: the number from your agreement, and who confirmed it.
• Observed fill rate: the category from your midpoint checks.
• Trap type and location: under bench or in-ground, and whether the lid is easy to reach.
• Paperwork you need: a service record that names the trap and shows where the waste went.

Supply all four and the cleaner can quote the right job. Supply none and you get a generic price that often does not match the visit.

Questions kitchen owners ask next

Can I service less often when business is slow?

No. The required frequency stays in force. Tell your cleaner about the slow period so they note a lighter trap on the record. If the change is long term, raise it with the authority.

Do enzyme or bio products replace a clean?

No. Water authorities such as the Water Corporation treat them as a supplement to pumping out, not a replacement. Check your own authority's position before you spend money on them.

Who should do the midpoint check?

A staff member trained to lift the lid safely, or the cleaner on a short inspection visit. Pick one person and one day so the check does not get lost.

What if the cleaner says the trap is fine but it smells?

A smell does not always mean a full trap. Our seven-step smell checklist covers the other causes. Either way, a smell is a reason to book a check, not to wait.

Where to get the schedule right in your area

Rules vary by state, authority and trap type, so treat any general guide as a starting point. For the national picture, our Australian grease trap regulations guide explains who sets what. For the environmental side, the NSW Environment Protection Authority publishes the rules on how liquid waste is transported and disposed of in that state.

If you are a licensed cleaner and want kitchen requests in your area, you can apply to join or see the territory pricing. To learn who runs the service, read about Grease Trap Quotes.

Your next step

Write down your required frequency this week. Check the trap at the midpoint of your next interval. Then put both facts into your next quote request.

Grease Trap Quotes sends three quotes from licensed cleaners by SMS, usually within about a minute of your request. The service covers Sydney today and is expanding to other Australian cities. Get three grease trap quotes now and see what the right schedule costs for your kitchen.

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Related reading: How to Dispose of Cooking Oil in Australia: Home, Cafe or Commercial Kitchen.

Related reading: Grease Interceptor Sizing Worksheet: The Inputs to Gather Before You Ask Anyone for a Size.