Frequently Asked Questions


Grease is a problem because it can cause blockages in sewer collection lines resulting in overflows of wastewater from the collection system. These overflows can potentially result in damage to property and/or environmental contamination of local bodies of water. Grease can adversely impact our wastewater collection system, equipment, and grease may also encumber wastewater treatment plants abilities to adequately treat the wastewater it receives. Although many believe pouring warm liquid grease down a drain is not harmful, once the grease cools, it hardens and may result in the blockages and overflows as describe above.

The name grease trap or grease interceptor is often used interchangeably. These devices are utilized to allow for the separation of fats, oils and greases in wastewater discharges from food service establishments and/or other type grease and oil generating establishments. Such traps or interceptors may be the “outdoor” or in-ground type normally 1,000 gallons capacity or greater, or the “under-the-counter” package units normally referred to as the under-the-counter grease traps.

Any Food Service Establishment (FSE) that introduces grease or oil discharges from kitchens, dish washing and any wastewater that is associated with food preparation should have a grease trap. This excludes residential occupancies that do not participate in the selling or preparation of food for commercial gain or business.

That depends on the discharge flow from the establishment and the amount of grease contained in the wastewater that discharges into the trap. The Universal Plumbing Code states that no grease trap should have a capacity less than 20 gallons per minute or more than 55 gallons per minute. Internal traps will need to be assessed based on the number of water generated fixtures it serves. The amount of grease in the wastewater can impact whether or not the establishment grease trap is able prevent grease from being discharged into the collection system. The FSE may need to implement practices in managing the handling of fats, oils and grease.

The first step is can you identify any under-the-counter containers where sinks and drains tie into? Check the plumbing drawing of the facility if available, to see if a grease trap is identified on the drawing. If you are still unsure you may wish to contact a plumber to assist you in tracing the discharge lines from the facility to see if they lead to a grease trap. Typically outside traps have manhole covers (some only 1 but typically 2). Outside grease traps are typically close to the kitchen section of the facility.

If your FSE discharges fats, oils and greases and does not have a grease trap eventually maintenance problems will occur with clogged sewer lines in the facility or backup situations in the wastewater collection lines in your service area. If you establishment is found to be the cause of such problems within the sewer service area, your establishment may be charged for any cost recovery associated with the maintenance and repair for any issues associated with the grease discharges.

Escalated enforcement is taken against an FSE that does not comply with the requirements found in City of Raleigh Public Utilities Department Handbook and/or does not comply with the requirements listed of the notice of noncompliance left by the Raleigh Water Inspector. Escalated enforcement can result in a civil penalty not exceeding $2000.00 a day per of noncompliance. A civil penalty may be issued for failure to comply and this failure shall be documented along with the assessed penalty with a deadline for payment unless otherwise documented.

Escalated enforcement is taken against an FSE that does not comply with the requirements found in City of Raleigh Public Utilities Department Handbook and/or does not comply with the requirements listed of the notice of noncompliance left by the Raleigh Water Inspector. Escalated enforcement can result in a civil penalty not exceeding $2000.00 a day per of noncompliance. A civil penalty may be issued for failure to comply and this failure shall be documented along with the assessed penalty with a deadline for payment unless otherwise documented

Maintenance, Reporting & Record Keeping
(a) Maintenance records shall be maintained onsite where the grease interceptor or oil/water separator is located for a period of three years.

(b) Grease interceptor maintenance records must include the following information.

  • FSE name and physical location
  • Date and time of grease interceptor service
  • Name of grease interceptor service company
  • Name and signature of person doing said service
  • Established service frequency and type of service (Example Full pump out, partial pump out, on site treatment, etc.)
  • Number and size of each grease interceptor serviced
  • Approximated amount, per best professional judgment, of grease
  • and solids removed from each grease interceptor
  • Total volume of waste removed from each grease interceptor
  • Destination of removed wastes, food solids, and wastewater disposal

(c) Maintenance records that do not include all the above information will be considered incomplete. Incomplete records are considered a violation of the City of Raleigh Sanitary Sewer Use Ordinance and may subject the facility to penalty assessments and/or service termination.

(d) Facilities for which a specific pretreatment permit has been issued will follow the requirements for maintenance and record keeping as stated in the permit.