Every restaurant in California that cooks food is required to have a working grease trap or interceptor. That requirement doesn't end at installation — it extends to a maintenance schedule, a documentation trail, and records available on demand when an inspector arrives. A grease trap that hasn't been serviced is a compliance problem before it's a plumbing problem.

This guide covers what California operators need to know: the regulatory framework, how to set a cleaning schedule that matches your actual operation, what documentation you're required to keep, and what happens when maintenance lapses.

The regulatory framework in California

Grease trap maintenance in California operates under two overlapping layers of regulation.

The California Plumbing Code (CPC), Chapter 10 establishes the statewide baseline for grease interceptor design, sizing, and installation. It delegates enforcement to the local Authority Having Jurisdiction (AHJ) — which means your local sewer agency, not the state, determines whether you need an interceptor, what size, and how often it must be serviced.

In LA County, that authority is LA Sanitation (LACSD), which operates one of the most stringent FOG (Fats, Oils, and Grease) control programs in California. Key requirements for LA County operators:

  • All new or remodeled food facilities installed after 2012 must have grease interceptors sized to handle peak flow rates — typically 1,000 gallons minimum for full-service restaurants
  • Existing facilities with under-capacity traps may face retrofit orders during permit renewals
  • Cleaning must be performed by a licensed waste hauler — not in-house staff pumping to a bucket
  • A maintenance log must be kept on-site for a minimum of 3 years, showing the date of each service, the hauler's name and license number, the volume of FOG and solids removed, and the disposal destination
  • Manifests from the licensed hauler serve as proof of legal disposal — these must be retained alongside the maintenance log
  • Records must be produced on demand during inspection. Missing or incomplete documentation is itself a violation, even if the cleaning was actually performed

Hood cleaning and fire suppression compliance fall under separate fire authority requirements. Grease trap compliance falls under LACSD. They are enforced independently — passing one inspection doesn't satisfy the other.

How often your grease trap needs to be serviced

The standard answer — every 90 days — is a minimum baseline, not a universal recommendation. The actual frequency depends on your trap size, your cooking volume, and how quickly FOG accumulates in your specific operation.

The governing standard in California is the 25% rule: a grease trap must be cleaned before FOG and solids reach 25% of the total wastewater depth in the trap. Once accumulation exceeds that threshold, the trap stops separating grease effectively — and grease begins escaping into the municipal sewer, which is exactly what FOG program inspectors test for.

Practical frequency guidelines by trap type:

  • Small indoor traps (under-sink, under 50 gallons) — weekly to biweekly service. These fill quickly and have no buffer for a missed service cycle
  • Mid-size indoor interceptors (50–500 gallons) — monthly to quarterly, depending on volume. High-volume kitchens typically need monthly service
  • Large outdoor interceptors (750+ gallons) — quarterly minimum for most operations; monthly for high-volume kitchens. In LA County, where cooking volumes and ambient temperatures accelerate FOG accumulation, quarterly is the floor for full-service restaurants, not the target

If you're unsure where your trap sits relative to the 25% threshold, have your hauler measure the FOG depth at the next service visit and document it. That measurement tells you whether your current frequency is adequate or whether you're consistently running close to the limit.

What a professional service visit includes

A compliant grease trap service visit is not just pumping out the contents. A complete service includes:

  • Full pump-out of liquid and solid contents using a vacuum truck
  • Flushing the trap with water after pump-out
  • Inspection of baffles, seals, and inlet/outlet pipes for damage or wear
  • Documentation of the volume removed — FOG and solids measured separately
  • A dated service manifest from the hauler showing their license number and the disposal destination

Keep the manifest. It's not optional paperwork — it's the evidence that the waste went to a legal disposal facility. Without it, you have a cleaning log but no proof of compliant disposal, which leaves you exposed if LACSD conducts an inspection.

Between professional service visits

Professional pump-outs handle the accumulation that staff can't address. Between visits, daily practices determine how quickly the trap fills and whether you're creating avoidable compliance risk.

  • Scrape plates and cookware into waste bins before washing — food solids that enter the drain accelerate trap filling and increase the volume of solids at the bottom
  • Never pour used fryer oil down drains. California law treats used cooking oil as a separately regulated waste stream — it must be collected by a licensed used oil collector, not disposed of through the grease trap. Pouring fryer oil into sinks is illegal even with a functioning grease trap
  • Keep the trap lid secured and sealed between service visits
  • Log any observations — unusual odors, slow drainage, or visible grease in unexpected locations — in the maintenance log. These are early warning signs that the service interval needs to decrease

The documentation system that keeps you compliant

California sewer agencies expect a specific set of records during a FOG inspection. The compliance log most LACSD inspectors look for:

  • Date of each service
  • Name and license number of the hauler
  • Volume of FOG removed
  • Volume of solids removed
  • Disposal facility destination
  • Copy of the hauler's manifest

This log must be kept on-site and produced on request. Most California municipalities require three years of records. Missing entries — even for a single service visit — are a citable violation. The log doesn't need to be elaborate: a dated sheet kept near the trap with each service entry is sufficient as long as it's complete and the manifests are attached.

What happens when maintenance lapses

A grease trap that hasn't been serviced on schedule doesn't fail quietly. The progression is predictable:

FOG accumulation exceeds the 25% threshold — the trap stops separating grease effectively — grease enters the municipal sewer — LACSD detects it during a routine sewer line inspection or responds to a complaint — your facility receives a FOG violation notice.

In LA County, FOG violations carry fines that escalate with repeat offenses. A first violation typically results in a compliance order and a required reinspection. Repeat violations can result in permit suspension. The cost of a single emergency pump-out for a backed-up system typically runs three to five times the cost of a scheduled service visit — before accounting for the revenue lost during any closure.

If your kitchen is already showing signs that the trap needs immediate attention — slow drains, persistent odors, or grease appearing in unexpected locations — the guide on recognizing grease trap warning signs covers what each symptom means and how urgently it needs to be addressed. For context on how grease trap compliance connects to your broader health inspection score in LA County, the analysis of 31,856 LA County inspections breaks down the violation categories and their point costs.