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What is a grease interceptor, and do I need one in NYC - New York City DEP?

What is a Grease Interceptor?

Contrary to grease traps that are used for smaller-scale water flow containing fats, oils, grease, and solids (FOGS), a grease interceptor is used for large-scale commercial kitchens that have higher flow rates and pressures. Typically, a grease interceptor is required when the volume of flow is above 50 gallons per minute as it is better equipped to handle the FOGS that flow through at that rate.

What is the Exact Purpose of an Interceptor?

All water has some percentage of oil in it as it flows through the city’s water pipes, however, when high-viscosity fats and oils are deposited into the city’s water system it can solidify and overwhelm the water pipes. The purpose of the interceptor is to trap the FOGS debris within a chamber where the debris is trapped, preventing them from escaping into the city’s water supply.

Since the oil and grease are lighter than the water within the chamber, they will float to the top. As for the solids that are denser than the water, they will sink to the bottom of the chamber until the interceptor is cleaned out by a licensed company.

So How do I Know if I Need One?

We have already touched on the volume of flow that specifies the necessity of a trap or an interceptor, so how will I know if I need one at all? If you are a restaurant owner in NYC, you will be required to have a grease trap or interceptor. However, you can get a request for an alternate device/sizing through the city that we will detail in a moment.

A grease interceptor shall not be required for individual dwelling units, private living quarters, or non-culinary schools which use residential-style stoves and sinks intended for teaching basic home cooking skills.

From Title 15 of the rules of the City of New York, restaurant owners are required to have all grease interceptors installed by a New York City Licensed Master Plumber. Grease interceptors are also required to be installed in any waste line which may receive fat, oil, and/or grease from all non-residential dischargers.

It is imperative to remember that commercial kitchen design in the city of New York must be done by a Registered Design Professional for approval by the NYC Department of Buildings. This will ensure compliance and make installation easy for your Licensed Master Plumber.

Basic NYC DEP Grease Interceptor Guidelines - New York City:

Device Approval

According to Title 15 of the Rules of the City of New York, all prefabricated grease interceptors and automatic grease removal devices shall either have been approved by the New York City Board of Standards & Appeals prior to July 10, 1991, approved by the New York City Department of Buildings Materials and Equipment Acceptance Division prior to July 1, 2008, or shall be designed and tested in accordance with the Plumbing and Drainage Institute standard PDI G101, or the American Society of Mechanical Engineers standards ASME A112.14.3 or ASME A112.14.4 and shall be installed in accordance with the manufacturer’s instructions.


For grease interceptor sizing, the required minimum flow rate in gallons per minute (gpm) and minimum grease retention capacity in pounds (lb) shall be applicable to hydromechanical grease interceptors. To determine the corresponding minimum size for gravity grease interceptors, such

minimum flow rate in gallons per minute shall be multiplied by 3. The resulting number shall be the minimum storage capacity in gallons that shall be required.

FOGS Removal Amount

Grease interceptors shall remove an average of 90 percent or more of the grease or other extractable matter in the wastewater before their rated grease retention capacity is exceeded.

Alternate Device/Sizing

In the case of existing grease interceptors, automatic grease removal devices must conform to the specific requirements of the Best Management Practices (BMP) within the Rules of the City of New York. There are times when the City of New York will allow for Licensed Engineers or Professional Architects to petition the Commissioner to confirm an alternate sizing of a device, technology, or equipment varying from those requirements listed in the Rules of the City of New York.

Why These Guidelines are Important

These guidelines are crucial to the functioning of the New York City water system. If these guidelines are not properly followed or ignored completely, the city will fine you until the issue is resolved. It is always advisable to contact the appropriate engineering and architectural services to ensure compliance of all requirements so that you can open and operate your business without concern.

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