Grease Trap Guide

A grease trap is designed to prevent greasy substances from entering plumbing systems, septic tanks, and waste water treatment facilities where they are difficult to process and may create a number of environmental problems. A grease trap is often specified for a pot washing sink or commercial dishwasher.

A flow restrictor on the inlet side of the trap slows incoming effluent material and redirects it through baffling inside the trap. This slowing and baffling process allows lighter-than-water substances (grease) to accumulate inside the trap above the static water line.

Local plumbing codes typically determine design and installation criteria, but they typically follow the guidelines set forth by the Plumbing & Drainage Institute (PDI).

How To Size*
Grease traps are sized according to the rate of incoming flow, in gallons per minute (GPM). Associated with this incoming flow rate is the trap's capacity. This rated capacity, in pounds, is listed at twice the flow rate. For example, a 10 GPM trap has a rated capacity of 20 pounds.

For Pot Washing Sink
The Plumbing and Drainage Institute (PDI) recommends that you round up to the next available size when determining the correct grease trap for your application.

If Draining Multiple Sinks Into One Grease Trap

1. Determine the flow rate for each sink to be serviced by the grease trap using the same calculations as a single sink. Add together 100% of the largest flow rate, 50% of the second largest, and 25% of all others.
2. The result is the recommended flow rate (in GPM) of the grease trap.

Calculating Grease Trap Requirements
For Dish Machines

We suggest that you use a drain maintainer or cleaner like EDM+ Enzymatic Drain Maintainer from Noble Chemical, or Noble Chemical Orange Peel Citrus Solvent Cleaner as part of a regularly scheduled cleaning and maintenance routine for your grease trap.