Grease Trap Size Calculator

Calculate the right grease trap capacity for your commercial kitchen.

Kitchen Fixtures

3-Compartment Sink

15 GPM

2-Compartment Sink

10 GPM

Prep Sink

5 GPM

Dishwasher

10 GPM

Mop Sink

3 GPM

Floor Drain

2 GPM

Waste Factor(75%)

Typically 0.75 (75%) for food service establishments. This accounts for grease content in wastewater.

Storage Capacity (Minutes)(2 min)

Time for grease to separate. Most jurisdictions require 2-3 minutes retention time.

What is a Grease Trap used for?

A grease trap (or grease interceptor) is a plumbing device that prevents fats, oils, and grease (FOG) from entering the municipal sewer system. It separates FOG from wastewater in commercial kitchens to prevent blockages and environmental damage. Local plumbing codes typically require them for all food service establishments.

How do I use this Grease Trap Calculator?

Enter the count of each fixture type (sinks, dishwashers, drains) in your kitchen. The calculator uses standard flow rates (GPM) to determine the total flow. Adjust the waste factor (standard is 75%) and storage time (standard is 2-3 minutes) to calculate the minimum required capacity and recommended trap size.

What is the formula for Grease Trap sizing?

The standard formula is: **Capacity (gallons) = Flow Rate (GPM) × Waste Factor × Storage Time**. Flow rate is the sum of GPM from all fixtures. Waste factor (0.75) accounts for grease content. Storage time (2-3 min) allows grease to separate. This method aligns with Uniform Plumbing Code (UPC) requirements.

What are the Grease Trap code requirements?

Most jurisdictions follow the Uniform Plumbing Code (UPC) or International Plumbing Code (IPC). You generally need a grease trap for any fixture receiving greasy waste. Maintenance logs are required, and cleaning frequency is typically mandated (e.g., every 30-90 days or when 25% full). Always consult local authorities.

Frequently Asked Questions

What is the difference between a grease trap and a grease interceptor?

Grease traps are smaller (under 100 gallons) and usually installed indoors under sinks. Grease interceptors are larger (100-2000+ gallons) and installed outdoors underground. Both separate FOG from wastewater, but size and location differ based on volume needs.

How often should a grease trap be cleaned?

Clean your grease trap when it reaches 25% FOG capacity, typically every 30-90 days. High-volume kitchens need more frequent service. Regular cleaning prevents backups, odors, and code violations.

Why is proper grease trap sizing important?

Proper sizing prevents overflows and backups. Undersized traps fail to separate grease, causing sewer blockages and fines. Oversized traps can be inefficient and accumulate hydrogen sulfide. Correct sizing ensures compliance and protects plumbing.

Can I size a grease trap based on sink dimensions?

No, sizing must be based on flow rate (GPM), not just sink size. You must account for all connected fixtures (dishwashers, floor drains, etc.) and calculate total GPM to meet plumbing code requirements.

What happens if I don't maintain my grease trap?

Lack of maintenance causes kitchen drain backups, foul odors, and sewer blockages. It leads to health code violations, fines, and potential business closure. Regular pumping and logging are essential for operation.