What to Do When a Grease Trap Overflows: The First Hour, Step by Step

It is 7:40 on a Friday night and the kitchen is full. A porter lifts the mat near the floor waste and finds a grey, greasy film creeping toward the dry store. The drain smells sour. The pot sink was draining slowly. Now it has stopped.

Most operators only think about the trap when it smells, backs up, or an inspection is due. By then it has already failed. What you do in the next hour decides whether you lose one service or a whole weekend.

Stop the flow first

Every litre that goes down a sink connected to a full trap has to go somewhere. It goes onto your floor.

Shut down the connected fixtures

Tell the team to stop using the pot sink, the pre-rinse spray, the dishwasher and any floor waste that feeds the trap. Put a sign on each one. If you do not know which fixtures feed the trap, ask your plumber or check your site plans. Do this before anything else.

Decide whether to keep trading

Grease and wastewater on a kitchen floor put staff at risk of slipping, and they create a food safety problem near prep areas. Safe Work Australia publishes guidance on managing slips, trips and falls at work. The NSW Food Authority sets out the food safety expectations for NSW businesses. If wastewater is reaching prep areas or you cannot wash equipment, stop cooking and clean up. Two hours with the kitchen closed costs less than an injury or a food safety breach.

Contain the spill

Work from the edge of the spill toward the middle.

• Block the path to other drains and doorways with towels, socks or absorbent material.
• Soak up the liquid with absorbent pads or granular absorbent from a hardware store.
• Bag the used absorbent and seal it in a bin. Do not wash it down a drain.
• Once the bulk is gone, mop the area with hot water and a degreaser, then dry it.

Keep every sink connected to the trap out of service while you work. Washing the floor down a drain that feeds the full trap sends the grease straight back where it started.

What not to do

Under pressure, people reach for fixes that make things worse.

Do not flush it through

Boiling water or caustic drain cleaner pushes the grease past the trap. It does not remove it. The grease travels down the line and sets again in the pipe, or it reaches the sewer. There it becomes the water authority's problem, and then yours. Trade waste rules exist because fats, oils and grease block sewers. Check the Sydney Water trade waste pages for the rules that apply to your site.

Do not scoop it into a bucket and tip it out

The lid is heavy. The contents are hot, foul and slippery. Lifting the lid without the right gear risks a burn, a fall or exposure to gases from the trap, so leave it alone unless your cleaner tells you otherwise. Never pour trap contents into a stormwater drain, a garden bed or a gutter. Grease in stormwater is an environmental offence, and the NSW EPA regulates pollution incidents in the state.

Call for an emergency pump-out

An overflowing trap needs a pump-out by a licensed cleaner. Ring one, tell them the trap has overflowed, and give them these details:

• Your address and where the trap sits (kitchen, car park, basement, laneway).
• Whether you can reach the lid, or whether it sits under a bench, a pallet or a parked car.
• Roughly how big the trap is, if you know.
• When it was last cleaned.

Clear the way to the lid before the truck arrives. If the cleaner has to wait while you shift stock, they charge for the wait.

No regular cleaner? Request three quotes. Grease Trap Quotes sends three quotes from licensed cleaners by SMS, usually within about a minute of your request. Cleaners price on trap size, service frequency, access to the trap and disposal fees. Two kitchens with the same trap can get quite different prices, so check what each quote includes. In an emergency, ask which cleaner can attend soonest and weigh that alongside price.

Work out why it overflowed

A pump-out clears the symptom. Finding the cause stops it happening again.

Check the schedule

Your trade waste agreement with the water authority sets the pump-out frequency for your kitchen. Many operators do not know theirs. Find your agreement and compare the required frequency with the date of your last clean. If you missed a service, the overflow was predictable. If you kept to the schedule and the trap still filled, your kitchen has probably changed since the schedule was set. A bigger menu, longer hours or a new fryer line all load the trap faster. Our guide to how the Wastesafe tracking system works explains how those records are kept.

Check what goes down the sink

Watch what your team scrapes, rinses and tips. Plates with food still on them, pans wiped straight into the sink and fryer oil poured down the pot sink fill a trap faster than any menu does. A scraping station and a clear rule for used oil cost nothing, and they often slow how fast the trap fills.

Check the trap itself

Ask the cleaner what they found. A damaged baffle, a blocked outlet or a cracked lid needs a repair, and a pump-out will not fix it. Get the finding in writing.

Record it and prepare for questions

Write down when you found the overflow, which fixtures you shut down, what you did, who you called and when the cleaner arrived. Keep the cleaner's docket. If the overflow reached a drain outside, or an inspector asks about it later, you have a clear record. Our walkthrough of what happens when Sydney Water inspects your venue covers what inspectors ask for. Your own pump-out records matter most.

If grease left the property or reached a stormwater drain, contact your water authority or council and ask what they need from you. Telling them early beats having them find out.

Book the next clean before you need it

An overflow makes for a bad night, but it is a useful warning. Set the next service date from your agreement, add a buffer for your busy season, and keep a cleaner you trust in your phone.

Grease Trap Quotes works with commercial kitchens, including restaurants, cafes, pubs, clubs, takeaways and food courts. The service covers Sydney today and is expanding to other Australian cities. Read more about us to see who is behind it.

If your trap has overflowed, or you want to fix the schedule before it does, get three grease trap quotes now. They arrive by SMS, usually within about a minute.

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Related reading: Grease Trap Servicing Before an Inspection: What to Have Ready When the Inspector Walks In.

Related reading: Who Sets the Grease Trap Rules in Australia?.

Related reading: Grease Trap Servicing for Operators With More Than One Kitchen.