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The Definitive Guide To Grease Traps

The Definitive Guide To Grease Traps

A grease trap is a device that forms part of a building’s plumbing system. Its purpose is to keep fats, oils, greases and solids out of the sewer system by providing a catchment for these materials before they pass into the general wastewater system.

What water does a grease trap catch?

Grease traps are designed to catch the water from the kitchen or workshop area, not the water from the bathroom or toilet. They can be made out of many different materials, like concrete, plastic or stainless steel and can be located within or outside of the building.

What types of businesses need grease traps?

Grease traps are commonly used by industrial and commercial businesses. These businesses can include service stations, car wash businesses, panel beaters, workshops, restaurants, shopping centres and commercial kitchens. Generally, any business that has a high volume of oil and food products being used in them are required to have grease traps professionally installed, cleaned and maintained.

Why are grease traps necessary?

Grease traps are an important part of a restaurant or workshop’s plumbing system because it’s very difficult for waste processing plants to break down fats, oils and greases (FOGs). If the oil and grease were to pass into the wastewater plant, there would be the risk that untreated water would enter the general water system and could potentially pollute waterways, like rivers and beaches. Another risk that is addressed by using a grease trap is the risk that the plumbing system would get blocked by fatbergs or the collection of oil and fat that can potentially become solid and collect when it has cooled down.

Grease trap requirements

Because of the risk to the environment, there are specific requirements around the types of grease traps that commercial businesses may install, as well as other equipment that may be required. Also, there are requirements around how to properly dispose of the waste generated by grease traps. For this reason, it’s required that you use a licensed plumber, like All Day Plumbing, to do the installation.

How is a grease trap maintained?

Because grease traps catch waste materials from businesses that handle food, chemicals and other materials, it’s best that they are maintained professionally.

There are several areas of maintenance involved in taking care of a grease trap. One important part is monitoring and inspecting the state of the trap. Regular observation will ensure that the trap does not overfill.

Another important area is emptying the contents of the trap. Upon inspecting, you’ll likely find that there is waste as well as water inside of the trap. The still water can be removed, leaving the waste in the trap. At this point in the maintenance process, it’s important to review your local, state and national requirements to understand if waste needs to be collected and disposed of by a licensed plumber like All Day Plumbing.

The next important part of the process is to clean the trap and reassemble it back to its original state.

Types of grease traps

Grease traps can be grouped in three ways:

Passive Hydromechanical (manual) – Passive systems are best suited for smaller organisations because they’re simple to install, come in different sizes and are relatively inexpensive in comparison to the other systems. They must be monitored and cleaned manually.

Automatic – Automatic systems give some assistance to the organisation by regularly heating the wastewater collected in the grease trap and removing the fat and oil from the system. These systems, while costing a bit more, reduce the amount of work the organisation needs to do.

Gravity – Gravity systems are built to accommodate businesses with high flows of activity to the system and are the most expensive. They’re usually located in an underground system outside and rely on the organisation pumping the waste out of the system regularly.

A professional can help you take a look at your business and its need to choose the right system for your organisation.


As you think about a grease trap system, you should keep the following things in mind:

  • Have we considered the maximum hourly flow the business requires?
  • Have we considered the growth of the business and if the maximum hourly flow is likely to increase in the future?
  • Is the grease trap installed so that gravity is in full effect to help the water flow in the direction of the drain?
  • Have we developed a maintenance plan to ensure the grease trap is regularly checked, maintained and cleaned?

What can go wrong with grease traps?

Common issues that can happen with grease traps are leaks and major spills. This can happen due to a malfunction of the grease trap, an improper re-installation after a clean, a blockage to the sewer or an overfill of the system.

Typically, business operations need to stop when a spill or leak occurs. The most important step is to stop the inflow of water to the grease trap to prevent further flooding or damage.

While cleaning is a natural step in the process, understanding why the leak happened can save time and money in the long run, especially if a professional is involved to help diagnose the problem quickly and precisely.

So, if you’re considering installing, cleaning, maintaining or replacing your grease trap, contact All Day Plumbing and we will answer any questions you may have.