Grease Removal or Recovery Unit (GRU)

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A GRU is a device designed to collect and remove grease from wastewater. Most GRUs separate grease from water by gravity.  Since grease weighs less than water, the grease floats and can be skimmed from the surface of the wastewater.

Section 1003.3.1 of the International Plumbing Code requires a GRU be installed to receive the drainage from fixtures and equipment with grease-laden waste located in food preparation areas. There are two types of GRU’s that are acceptable for installation in the NBC districts. One type of GRU is the automatic electrical/mechanical GRU. The other acceptable type is the large in-ground passive type of GRU. Prior to purchasing or installing a GRU, approval must be granted from NBC Pretreatment office. Pretreatment staff will provide guidance throughout the review and approval process to ensure the GRU selected meets NBC criteria, avoiding the need for costly retrofits.

Click here for a list of equipment manufacturers of grease removal systems.

Prior to purchasing or installing a GRU, approval must be granted from NBC Pretreatment staff. NBC staff provides guidance necessary to ensure that the GRU selected meets NBC criteria. Contacting the Pretreatment section at 401-461-8848, ext. 490 in advance may prevent a company from incurring expensive GRU retrofit costs should initial installation not satisfy NBC criteria. To receive approval, technical information on the proposed GRU must be submitted to the NBC along with plans of the kitchen facility. The plans must show all wastewater generating equipment and piping to the GRU. A sample port directly downstream of the GRU must be shown on the plans. There must be a minimum eight inch clearance for the installation of sampling bottles.