Emergency Grease Trap Overflow: What to Do When Your Trap Backs Up

A grease trap overflow is one of the most disruptive emergencies a Melbourne commercial kitchen can face. Contaminated wastewater backing up onto your kitchen floor creates an immediate health hazard, shuts down food preparation, risks damage to your premises, and can trigger serious regulatory consequences if fats, oils, and grease enter the stormwater system.

Knowing exactly what to do in the first minutes of an overflow can make the difference between a contained incident and a full-blown crisis. Here is your step-by-step emergency response guide.

Immediate Response: The First 10 Minutes

Step 1: Stop All Water Use Immediately

The moment you notice water backing up from floor drains, sinks overflowing, or wastewater pooling around your grease trap, stop all water usage in the kitchen. Turn off dishwashers, stop running taps, and halt any cleaning activities. Every litre of water you add to the system will worsen the overflow.

Communicate clearly and quickly with all kitchen staff. Everyone needs to know the situation and that no water should go down any drain until the issue is resolved.

Step 2: Contain the Spill

Prevent the overflow from spreading as much as possible:

Use absorbent materials (kitty litter, absorbent pads, or towels) to create barriers around the spill
Block doorways to prevent contaminated water from reaching dining areas
If the overflow is near an external stormwater drain, block that drain immediately — FOG entering the stormwater system is a serious environmental offence under EPA Victoria regulations
Place wet floor signs to prevent slip injuries — grease-contaminated water is extremely slippery

Step 3: Call for Emergency Professional Cleaning

Contact an emergency grease trap cleaning service immediately. A professional team with a vacuum truck is the only way to resolve the overflow properly. When you call, provide:

Your business name and address
The type and size of your grease trap (if known)
A description of the overflow — how much water, where it is going, and whether it is reaching any external drains
How long ago the overflow started

Most professional services in Melbourne offer emergency response with rapid arrival times, particularly for Melbourne CBD and inner-city locations where the risk of environmental impact is highest.

While Waiting for the Emergency Team

Protect Your Staff

Grease trap overflow water contains bacteria, decomposing organic matter, and potentially harmful gases. Ensure staff who are managing the spill wear rubber gloves and waterproof footwear at minimum. Keep unnecessary personnel away from the affected area.

If the overflow is from an enclosed or underground trap, be aware of hydrogen sulphide gas, which smells like rotten eggs. If anyone experiences dizziness, nausea, or difficulty breathing, evacuate the area immediately and call emergency services.

Document the Incident

While it may not be your first priority in the moment, documenting the overflow is important for insurance claims, regulatory reporting, and preventing recurrence:

Take photos and videos of the overflow area, the grease trap, and any affected equipment or stock
Note the time the overflow was first noticed
Record what was happening in the kitchen at the time (number of staff, volume of cooking, which equipment was running)
Note whether any wastewater reached external drains or stormwater systems

Do Not Attempt to Pump the Trap Yourself

It can be tempting to try to relieve pressure by scooping or bucketing waste out of the trap. This is strongly inadvisable:

You risk exposure to harmful biological material and gases
Grease trap waste removed this way still needs legal disposal — you cannot put it in bins or pour it elsewhere
You may damage trap components in the rush to remove waste
It will not resolve the underlying blockage or overflow

Wait for the professional team. They have the equipment, training, and disposal capabilities to handle the situation safely and legally.

After the Emergency Clean

Thorough Area Cleaning and Sanitisation

Once the grease trap has been pumped out and the overflow resolved, the affected area needs thorough cleaning and sanitisation. Grease-contaminated wastewater on kitchen floors, under equipment, and on walls must be cleaned with appropriate commercial sanitisers to eliminate bacteria and prevent odour.

Depending on the extent of the overflow, you may need to arrange professional cleaning of the kitchen area, particularly if wastewater has reached food storage or preparation surfaces.

Check Connected Drain Lines

An overflow often indicates that the problem extends beyond the grease trap itself. Solidified grease in downstream drain lines can cause backups even when the trap has recently been cleaned. Ask your service provider about drain line cleaning to clear any blockages in connected plumbing.

Assess and Repair Any Damage

Overflow incidents can cause damage to:

Flooring (particularly timber or laminate)
Electrical equipment that was exposed to water
Wall linings and skirting boards
Stock and supplies stored at floor level

Document all damage thoroughly for your insurance claim and arrange repairs promptly to get your kitchen back to full operation.

Report to Your Insurer

Most commercial kitchen insurance policies cover grease trap overflow incidents, but prompt reporting is usually required. Contact your insurer as soon as the immediate emergency is resolved, and provide the documentation you gathered during the incident.

Regulatory Obligations

If grease trap overflow reaches the stormwater system, you may be required to report the incident to EPA Victoria and your local water authority. Stormwater contamination with FOG is treated as an environmental incident, and failure to report can compound the penalties.

Your professional cleaning service can help you determine whether reporting is required and assist with providing the necessary documentation.

Preventing Future Overflows

An overflow is a clear signal that your current maintenance regime is inadequate. After the emergency is resolved, take these steps to prevent it from happening again:

Increase your cleaning frequency: If your trap overflowed, it was not being cleaned often enough. Work with your service provider to establish a more frequent pump-out schedule.
Monitor FOG levels regularly: Weekly visual inspections help you catch rising levels before they reach critical points. Review the warning signs that your grease trap needs cleaning so your team knows what to watch for.
Improve kitchen practices: Ensure all staff are scraping plates properly, using sink strainers, and never pouring oil down drains.
Check trap sizing: If your business has grown or your menu has changed to include more oil-intensive cooking, your grease trap may now be undersized for your needs. A professional assessment can determine whether an upgrade is required.
Set up a maintenance plan: Regular, scheduled pump-outs are the most reliable way to prevent emergencies. The cost of planned maintenance is a fraction of emergency call-outs, lost trade, and remediation expenses.

Do Not Wait for an Emergency

If you are reading this article because your trap has already overflowed, focus on the immediate response steps above and call for emergency professional help. If you are reading this to be prepared, that is smart planning — but the best preparation is making sure an overflow never happens in the first place through regular professional cleaning and proper kitchen maintenance practices.

Contact us today to arrange a grease trap assessment and set up a maintenance schedule that keeps your Melbourne kitchen safe, compliant, and overflow-free.

Emergency Grease Trap Overflow: What to Do When Your Trap Backs Up