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How a Grease Trap Works

How a grease trap works

The purpose of a grease trap (or interceptor) is to prevent grease and food solids from entering the sanitary sewer system. This is accomplished by capturing all of the waste deposited in the drain (mostly water) in the primary separation basin. The water in the trap (from the drains) cools the grease to room temperature, solidifying it. Because grease is lighter than water, it floats to the top. the food solids, that are heavier than water sink to the bottom.

A crossover pipe located in the middle of the wall separating the primary from the secondary separation compartment allows the cleaner water to flow into the

secondary separation basin. The “primary” provides the majority of the separation, while some of the grease still suspended in the water makes its way through the crossover and is captured in the “secondary” creating a second separation.

The outgoing line leaves the secondary and establishes the normal liquid level, then it will flow to the sanitary sewer system.

A properly functioning grease trap should always maintain a normal liquid level. This does not indicate that the trap is “full”.