How Often Should You Clean a Grease Trap?

It’s the question every restaurant and commercial kitchen eventually asks: how often does a grease trap actually need to be cleaned? Clean too rarely and you risk backups, odors, and failed health inspections. Clean too often and you’re spending money you don’t need to. Here’s how to find the right schedule.

The 25% Rule

The industry standard — and the rule most local FOG (Fats, Oils & Grease) ordinances follow — is the 25% rule: your grease trap should be pumped before the combined layer of fats, oils, grease, and solids reaches 25% of the trap’s total liquid depth. Past that point, the trap can no longer separate grease effectively, and it starts flowing straight into your drain lines.

Typical Cleaning Schedules

Most commercial kitchens land somewhere between monthly and quarterly. As a general guide:

• Every 1–4 weeks: high-volume kitchens, fryer-heavy menus, and small under-sink traps that fill fast.
• Every 1–3 months: the majority of full-service restaurants and cafes.
• Every 3–6 months: lower-volume kitchens or facilities with large in-ground interceptors.

The right number depends on your trap size, menu, and cooking volume — a small 20-gallon trap at a busy fry spot may need service every two weeks, while a 1,000-gallon interceptor might go a few months.

Signs Your Grease Trap Is Overdue

• Slow drains or gurgling near floor drains and sinks
• Foul, sewage-like odors in the kitchen — especially during service
• Grease visible at the trap lid or backing up into floor sinks
• It’s been longer than your permit allows since the last documented service

If you’re seeing any of these, don’t wait for the next scheduled visit — a full trap is a backup waiting to happen on your busiest night.

Why a Set Schedule Beats Waiting

Reactive cleaning — waiting until there’s a problem — almost always costs more than a recurring plan. Emergency call-outs, kitchen downtime, health-code violations, and drain-line damage add up fast. A recurring maintenance schedule keeps your trap under the 25% threshold, keeps you inspection-ready with documented service records, and takes the guesswork off your plate.

Not Sure What Your Trap Needs?

JN Grease Service will assess your trap size and cooking volume and recommend the right interval — then handle the service on a schedule built around your hours. We document every visit for your FOG-compliance records, and we’re available 24/7 if a trap backs up in between.