As grease collects in large quantities, it can harden and clog sewer systems. Many people carelessly dispose of grease in drains, which can cause issues if the grease were to harden. Restaurants and other professional food businesses create large quantities of grease from cooking. In New Jersey, these types of businesses must install grease traps in order to lessen the damage to the sewer systems. Compliance with New Jersey State Code 7:9, which regulates sewage disposal systems, is required for all restaurants, cafeterias and institutional kitchens.

Installation Requirements

According to New Jersey Administrative Code 7:9A-8.1, grease traps must be installed with a separate line in to the plumbing system. The trap must be near "the source of wastewater, where the wastewater is still hot, to facilitate separation." All grease traps must be easy to access and clean. No grease trap in a restaurant, institutional kitchen or cafeteria may be smaller than 750 gallons.

The Equation

The administrative code establishes an equation to determine the size of grease trap needed beyond the initial 750 gallons. The equation is Q = (D) x (HR/2) x (12.5) x (LF), where Q is the size of the grease trap in gallons; D is the number of dining area seats; HR is the open hours; and LF is the "loading factor," which is determined by the restaurants location. The loading factor for a restaurant along an interstate freeway is 1.25; 1.0 for non-interstate freeways; 1.0 for recreation areas; 0.8 for main highways; and 0.5 for other highways. The equation varies for cafeterias and institutional kitchens: Q = (M) x (11.25) x LF. In this equation, M is defined as the total number of meals per day and LF is either 1.0 for facilities with dishwashing or 0.5 for facilities without dishwashing.


Section F of N.J.A.C. 7:9A-8.1 states that grease traps must be constructed under the same requirements as septic tanks. Septic tanks, under N.J.A.C. 7:9A-8.2, must be water-tight and resistant to corrosion, decay, frost damage, cracking and backfilling.

Additional Requirements

The grease trap's inlet and outlet must be provided with "'T' baffles extending to a depth of 12 inches above the tank floor and well above the liquid level." Manholes, for grease trap maintenance, are also required. The manhole cover must be gas-tight and capable of handling "expected loads." The frequency in which grease traps should be pumped will be listed in a triennial notification from an administrative authority for business owners.