Grease Trap Requirements in Atlanta
Grease trap requirements govern food service establishments, commercial kitchens, and institutional food preparation facilities operating within Atlanta's jurisdiction. These requirements exist to prevent fats, oils, and grease (FOG) from entering the municipal sewer system, where accumulation causes blockages, overflows, and costly infrastructure damage. The Atlanta Department of Watershed Management enforces FOG-related ordinances under authority derived from local code and the Georgia Environmental Protection Division's general pretreatment program standards. Understanding the regulatory landscape is essential for any operator, contractor, or property developer involved in commercial food service in the city.
Definition and scope
A grease trap — also called a grease interceptor when referencing large-capacity in-ground units — is a passive mechanical device that intercepts and retains fats, oils, and grease before wastewater enters the public sewer system. The distinction between a grease trap and a grease interceptor is functional and size-based:
- Grease trap (passive, under-sink): Smaller units installed below or near the fixture, typically rated at 10 to 100 gallons per minute (GPM) flow capacity. These serve lower-volume operations such as cafes or small diners.
- Grease interceptor (in-ground, gravity-type): Larger tanks, often 500 to 2,000+ gallon capacity, buried outside the facility. Required for high-volume food service operations. Governed by sizing standards under the Uniform Plumbing Code (UPC) and the International Plumbing Code (IPC).
Scope of this page: This reference covers grease trap requirements as enforced within the City of Atlanta's incorporated limits under the jurisdiction of the Atlanta Department of Watershed Management and applicable Fulton and DeKalb county sewer agreements. Requirements for unincorporated Fulton County, Gwinnett County, Cobb County, or other metro-Atlanta municipalities are not covered here. Operations subject to industrial pretreatment permits under the U.S. Environmental Protection Agency's National Pretreatment Program (40 CFR Part 403) may have additional obligations not addressed in this page.
How it works
Grease interceptors operate on the principle of differential density. Wastewater from kitchen drains enters the interceptor's inlet chamber. Because fats and oils are less dense than water, they float to the surface, while heavier solids settle to the bottom. Clarified effluent exits through the outlet baffle into the sewer system.
The operational sequence in a properly functioning interceptor:
- Inlet: Kitchen wastewater enters through a baffle that slows flow velocity, allowing separation to begin.
- Retention zone: FOG accumulates at the surface; grease cap builds over time between service intervals.
- Solids trap: Food particles and sediment settle at the tank bottom.
- Outlet: Clarified water exits below the grease layer through an outlet baffle or dip pipe.
- Maintenance cycle: Accumulated FOG and solids must be pumped and disposed of by a licensed waste hauler. Atlanta's Watershed Management program requires manifests and records of each pump-out.
Interceptor sizing is calculated using a formula based on drainage fixture units (DFUs), flow rate in GPM, and retention time — typically 30 minutes minimum under IPC standards. A 3-compartment sink draining at 50 GPM with a 30-minute retention time would require, at minimum, a 1,500-gallon interceptor before applying applicable safety factors.
For a broader orientation to Atlanta's plumbing regulatory environment, the regulatory context for Atlanta plumbing page describes the governing agencies and code adoption framework relevant to commercial systems.
Common scenarios
New food service construction: Any new restaurant, commissary, or institutional kitchen in Atlanta requiring a commercial plumbing permit must demonstrate interceptor compliance before the Certificate of Occupancy is issued. The Atlanta Department of Building permits coordinates with Watershed Management for FOG-generating occupancies.
Change of occupancy: A retail space converting to a restaurant use triggers grease interceptor requirements even if the previous tenant had none. The permit application must include an interceptor sizing calculation signed by a licensed Georgia plumber or engineer.
Existing operations added to FOG enforcement: Watershed Management's pretreatment staff conducts inspections and may issue FOG compliance notices to operating food service establishments found discharging excess grease. Violations can result in surcharges or sewer service termination under Atlanta's sewer use ordinance.
Food trucks and mobile operations: Mobile food preparation units connecting to a fixed facility's sewer system are subject to FOG requirements through the host facility's interceptor. Standalone mobile units discharging at commissaries must comply with commissary interceptor capacity requirements.
Institutional facilities: Schools, hospitals, and correctional facilities with on-site kitchens fall under the same grease interceptor requirements as commercial restaurants. Sizing often produces large interceptor requirements — facilities serving 500 or more meals daily commonly require interceptors of 2,000 gallons or greater.
Commercial plumbing in Atlanta covers the broader permitting and inspection framework for non-residential plumbing installations, of which grease systems are a subcategory.
Decision boundaries
Determining whether a grease trap or interceptor is required — and what size — depends on several classification criteria:
| Factor | Under-sink Trap (Small) | In-ground Interceptor (Large) |
|---|---|---|
| Flow rate | ≤ 50 GPM | > 50 GPM |
| Meals served daily | Fewer than 100 | 100 or more |
| Operational classification | Low-volume café, limited prep | Full-service restaurant, commissary |
| Governing standard | UPC Table 1003.3.4 | IPC §1003.3, local sizing ordinance |
When no grease device is required: Facilities that do not prepare food — such as convenience stores selling pre-packaged goods, beverage-only outlets without cooking equipment, or office break rooms — generally fall outside FOG program requirements. Watershed Management makes this determination case-by-case based on fixture inventory submitted with the permit application.
Inspection and record-keeping obligations: Atlanta's FOG program requires food service establishments to maintain pump-out records for a minimum of 3 years and make them available for inspection on demand. Failure to maintain records constitutes a separate violation from failure to service the interceptor.
For the full Atlanta plumbing authority index — covering all commercial and residential plumbing topics under this reference — see Atlanta Plumbing Authority.
References
- Atlanta Department of Watershed Management — FOG program administration and sewer use ordinance enforcement
- Georgia Environmental Protection Division — Wastewater Program — State pretreatment program standards applicable to Atlanta's sewer system
- U.S. EPA National Pretreatment Program — 40 CFR Part 403 — Federal pretreatment standards baseline
- International Plumbing Code (IPC) — ICC — Grease interceptor sizing methodology, §1003.3
- Uniform Plumbing Code (UPC) — IAPMO — Alternative grease trap standards, Table 1003.3.4
- Georgia Secretary of State — State Plumbing Code Adoption — State-level code adoption context for licensed plumbing work in Georgia