How Often Should a Restaurant Clean Its Grease Trap?

Why volume, not time, should set the schedule

Two restaurants of similar size can have very different grease trap needs depending on their menu: a kitchen doing heavy fryer volume generates far more grease than one focused on salads and cold prep. Setting a fixed interval without accounting for that difference means either over-servicing a light kitchen, wasting money, or under-servicing a heavy one, risking the backup that happens when the trap overflows mid-service.

What overflow actually costs you

When a trap fills past capacity, grease carries into the drain line and the kitchen backs up, often during service rather than at a convenient time. Beyond the immediate disruption, a backed-up commercial kitchen can trigger a health-code issue serious enough to stop operations. The cost of that scenario dwarfs the cost of one more scheduled cleaning, which is the whole argument for erring toward a slightly shorter interval rather than stretching it.

The twenty-five percent rule and why it's a starting point, not a law

A commonly cited guideline in grease trap management is servicing the trap once it reaches roughly twenty-five percent full of grease and solids, since allowing it to fill further reduces its effective capacity to separate grease from wastewater. This is a useful starting reference, but it still requires knowing your trap's actual fill rate to translate into a calendar schedule, since a trap that reaches twenty-five percent in two weeks needs a very different service calendar than one that takes two months to reach the same point.

What happens during a professional service visit

A proper service visit removes the accumulated grease and solids, cleans the trap's interior surfaces rather than simply pumping out the liquid layer, checks the condition of internal baffles or screens, and documents the volume removed, which becomes useful data for refining your service interval over time. Some services also include a brief inspection of the drain line immediately downstream of the trap, since that section is the first to show signs if grease has been slipping past the trap's capacity between services.

Under-sink versus in-ground grease interceptors

Smaller food establishments often use an under-sink grease trap, while larger commercial kitchens may have a bigger in-ground grease interceptor, and the two have different typical service intervals given their different capacities. Knowing which type your establishment has, and confirming its actual rated capacity, is a useful piece of information when setting or reevaluating your specific service schedule, since interceptor size is one more factor beyond just kitchen volume that affects the right interval.

Signage and staff training as part of the picture

Beyond the trap itself, staff practices in the kitchen meaningfully affect how fast a grease trap fills: scraping plates into the trash before washing, using strainers in prep sinks, and avoiding pouring cooking oil directly down the drain all reduce the grease load reaching the trap in the first place. A kitchen with good staff habits around grease disposal can sometimes extend its service interval compared to an otherwise similar kitchen with looser practices, which is worth factoring in alongside menu and volume when setting a realistic schedule.

What happens to the grease once it's removed

Grease removed during a service visit is typically transported to a licensed recycling or disposal facility, since used cooking grease and food-service grease waste cannot simply be discarded as ordinary trash in most jurisdictions, including Arizona. Some facilities process this waste into biodiesel or other reusable byproducts, meaning a well-managed grease trap service is not just a compliance obligation but also connects to a broader recycling stream for what would otherwise be a purely disposal problem. Asking your service provider where collected grease is taken can also be a reasonable due-diligence question, since proper disposal documentation is sometimes requested as part of a compliance review for food establishments.

Adjusting the schedule around seasonal menu changes

A restaurant that shifts its menu seasonally, leaning more heavily into fried or heavier dishes during cooler months and lighter fare in summer, may see its actual grease output shift correspondingly, which is worth factoring into the service schedule rather than assuming one fixed interval fits every season equally. A kitchen that tracks this kind of seasonal pattern over a year or two can fine-tune their grease trap schedule to match, potentially saving on off-season service costs while ensuring adequate coverage during heavier-output months.

One final note: if you're evaluating a new grease trap service provider, ask specifically how they determine the interval for a kitchen like yours rather than accepting a generic answer, since a provider that actually assesses your specific fill rate and adjusts accordingly will generally save you money over time compared to one that defaults to the same fixed schedule for every client regardless of their kitchen's actual volume.