Selecting the correct grease trap size is vital for effective Fats, Oils, and Grease (FOG) management in commercial kitchens. Without an adequately sized grease trap, your drainage system could face costly blockages, foul odours, and compliance issues. This guide highlights how Filta supports commercial kitchens in determining the optimal grease trap size for their unique requirements.

What Factors Should Determine Your Choice?

When choosing the right grease trap, it’s essential to evaluate several factors to ensure it meets your kitchen’s specific needs. Key considerations include the wastewater flow rate, the type of establishment you operate and how frequently the kitchen is used.

Wastewater Flow Rate:

The volume of wastewater your kitchen produces and how quickly it moves through the system directly impacts the grease trap size required. Larger kitchens with pre-rinse areas, pot wash sinks, mop sinks and multiple appliances such as dishwashers produce significant amounts of wastewater. These setups demand larger grease traps to efficiently handle the flow and capture FOG before it enters the drainage system. Conversely, smaller operations with lower output can be managed with a smaller grease trap.

Type of Establishment:

Different food service businesses generate varying levels of grease. Categorising your establishment helps pinpoint the right size grease trap or grease removal unit (GRU):

  • Low Grease Flow: Convenience stores, delis, snack bars, and sandwich shops generate minimal FOG. These establishments typically require smaller grease traps.
  • Medium Grease Flow: Coffee shops, cafes and takeaways. They produce a moderate amount of grease and would require medium-sized grease traps.
  • High Grease Flow: Cafeterias, hotels, schools, universities, hospitals etc, produce significant grease volumes. Larger grease traps or advanced GRUs are ideal for these high-output environments.

Calculating Grease Trap Size:

As a general rule of thumb, a grease trap should hold at least 20-30 minutes worth of wastewater flow. This allows sufficient time for the FOG to separate from the water.
To determine the correct grease trap size, follow these steps:

Step 1: Measure Sink Volume

Measure the sink’s length, width, and depth in centimetres. Multiply these dimensions to calculate the total volume in cubic inches.
Convert the volume to litres by dividing the total by 1,000 (since 1,000 cubic centimetres equals 1 litre).

Step 2: Calculate Flow Rate

Fill the sink and time how long it takes (in minutes) to fill completely.
Divide the sink’s volume (in litres) by this time to determine the Litres Per Minute (LPM) flow rate.

Step 3: Calculate Total Flow

For kitchens with multiple sinks or appliances, add together each device’s LPM flow rate to determine the peak flow rate for the entire kitchen.
This calculated LPM flow rate serves as a baseline for selecting the grease trap or GRU that will effectively handle your kitchen’s peak load.

Many factors can affect the size of a grease trap, to ensure you have the right unit installed at your premises, speak to Filta for a free-of-charge site survey.

Grease Trap and Grease Recovery Unit Top Tips, Advice & Guides

Managing FOG isn’t just about installing the right grease trap, it also requires regular maintenance, cleaning, and adherence to best practices. For detailed advice and answers to common questions about grease traps, visit Filta’s FAQ on grease trap cleaning.

By keeping your grease trap well-maintained, you’ll avoid common issues such as system blockages, unpleasant odours, and potential fines for non-compliance with environmental regulations.

Selecting the correct grease trap size for your commercial kitchen is not only a regulatory necessity but also a smart investment in your establishment’s long-term efficiency and sustainability. By assessing your wastewater flow rate and understanding your grease production, you can make an informed decision tailored to your needs.

For expert guidance, on choosing the right grease trap size for your kitchen, contact Filta today at 01788 550 100 or fill out our contact form.