A busy commercial kitchen can send a surprising amount of fat, oil, and grease down the drain in a single service. Without the right interceptor or grease trap in place, that material cools, hardens, and creates blockages where nobody wants them – in the building drain or the public sewer. Commercial grease trap requirements exist to stop that chain reaction before it starts.
For restaurant owners, builders, property managers, and commercial tenants, this is not a box-ticking exercise. A poorly sized, badly installed, or neglected grease management system can lead to backups, kitchen downtime, cleanup costs, and action from the local authority. Getting it right at the design stage is usually far less expensive than fixing a failed drainage system later.
What Commercial Grease Trap Requirements Cover
The exact rules depend on the city, sewer authority, building code, and the nature of the business. A coffee shop, full-service restaurant, bakery, supermarket deli, and commercial food production facility do not produce the same wastewater, so they should not automatically receive the same solution.
Most commercial grease trap requirements address four practical areas: whether a grease interceptor is required, where it must be installed, how it must be sized, and how it must be maintained. Plans may also need approval before work begins, particularly when a new food business connects to public sewer or an existing tenancy is converted into a kitchen.
The goal is straightforward. Wastewater from food preparation, pot washing, dishwashers, floor drains, and other nominated fixtures should pass through equipment that separates grease and settled solids before the water enters the drainage system. Not every fixture belongs on the grease line. Restrooms, for example, should remain separate.
A qualified plumbing and drainage contractor can review the proposed kitchen layout, fixture schedule, menus, expected covers, and operating hours before recommending a system. That early coordination matters. Grease control is tied to drainage design, floor levels, access for cleaning, and the location of other services.
Grease Trap or Grease Interceptor: Choosing the Right System
The terms are often used interchangeably, but the equipment can be very different. A smaller indoor grease trap is commonly installed close to the source, while a larger exterior grease interceptor is generally designed for higher flow rates and more demanding commercial kitchens.
The right choice depends on the site. A compact food outlet in an existing building may have limited room and may need a carefully located internal unit. A new restaurant with a high-volume dishwashing operation may be better served by a larger external interceptor with easy truck access for pumping. Neither is automatically better. Capacity, accessibility, local rules, and the kitchen’s actual discharge all matter.
Automatic grease removal units can also suit some operations, but they are not maintenance-free. They still need regular checks, correct operation, and disposal of collected material. Buying sophisticated equipment does not remove the need for a realistic maintenance plan.
Avoid selecting a unit based only on what fits under a sink or what appears cheapest upfront. An undersized unit fills too quickly and allows grease to pass through. An oversized unit can add unnecessary installation cost and may be difficult to accommodate on a tight site. Good design balances performance, access, and future operating costs.
Sizing Is Based on Real Kitchen Demand
Sizing methods differ between jurisdictions, but they generally consider the flow from connected fixtures and the amount of grease the operation is likely to generate. Relevant details may include sink dimensions, compartment count, dishwasher discharge, flow control devices, fixture drain sizes, seating capacity, meal volume, and operating hours.
This is why a kitchen change can trigger a review. Adding a combi oven, expanding prep space, increasing seating, or changing from light café service to full meals can substantially alter the grease load. The existing trap may no longer be appropriate, even if it has not caused an obvious problem yet.
A proper assessment also considers water temperature. Hot water can keep grease liquid long enough to move through an inadequate interceptor, only for it to solidify farther down the line. High-efficiency hot water equipment can improve operational performance, but it does not replace correctly sized grease management.
Installation Details That Make or Break Compliance
A grease interceptor needs more than a connection to the drain. It must be installed where it can do its job and where it can be serviced safely. That usually means allowing enough clearance to open lids, remove internal components, inspect the unit, and pump it out without disrupting the entire business.
Exterior units should be positioned away from traffic loads unless they are designed and rated for those conditions. Covers need to be accessible and secure. Internal units need suitable ventilation where required, protection from damage, and a layout that allows staff or service contractors to reach them without moving appliances or shutting down a food-preparation area.
Flow control is another detail that should not be overlooked. Many systems rely on controlled flow to provide enough retention time for grease to separate from water. If a unit is bypassed, improperly vented, connected to unsuitable fixtures, or fitted without the required flow control arrangement, it may not perform as intended.
For new builds and major renovations, coordinate grease equipment early with the architect, kitchen designer, builder, and drainage contractor. Late changes often create avoidable compromises, such as a unit placed in an inaccessible corner or a drain route that requires unnecessary pumps and bends.
Maintenance Is Part of the Requirement, Not an Afterthought
A correctly installed unit can still fail if it is not cleaned. Grease traps and interceptors work by collecting grease and solids. Once those materials build up, the available treatment volume shrinks and performance drops.
Many authorities set cleaning frequencies or require the unit to be pumped before grease and solids exceed a specified portion of its capacity. The exact interval may be monthly, quarterly, or based on the operation’s waste volume. A high-output restaurant may need much more frequent servicing than a small café. The practical rule is to inspect regularly and service according to the manufacturer’s instructions and local requirements, not only after a blockage occurs.
Kitchen staff also make a difference. Scrape plates and cookware into the trash before washing, use strainers where appropriate, and keep food scraps out of sinks. Never treat a grease trap as a disposal unit for cooking oil, wet wipes, chemicals, or large quantities of food waste. Used cooking oil should be collected separately through an appropriate disposal or recycling arrangement.
Keep service records on site. Pump-out invoices, inspection notes, waste manifests where applicable, and repair records provide evidence that the system is being managed. They are also useful when a new manager takes over, a landlord reviews the tenancy, or an inspector asks for documentation.
Common Problems We See in Commercial Kitchens
The most expensive grease issues often begin with small oversights. A trap is installed but cannot be accessed. A kitchen expands without checking capacity. Staff use hot water and detergent in the belief that grease has disappeared, when it has simply moved farther down the pipe. Or a maintenance schedule is skipped during a busy season.
Warning signs include slow-draining sinks, recurring odors, gurgling drains, grease around covers, wastewater backing up at floor drains, and repeated calls for drain clearing. These symptoms need prompt attention. Jetting a blocked line may restore flow, but it will not solve an undersized or neglected interceptor.
If you are planning a commercial kitchen, taking over a food tenancy, or dealing with recurring drainage problems, start with a site-specific review. Alchemy Plumbing & Gas can assess the drainage layout, grease management equipment, access, and likely compliance obligations, then recommend a solution built for the way your kitchen actually operates.
The best time to address grease is before the first busy service – when there is still room to design a system that protects the kitchen, the property, and the sewer network behind it.