Restaurant Grease Interceptor Compliance: South Bay Guide (2025)

Kitchen wastewater carries emulsified fats, free-floating oils, and food solids. At normal drain temperatures, that material flows easily — but it cools in the sewer lateral and solidifies into a paste that blocks pipes and damages collection infrastructure. A grease interceptor is a baffled tank, installed between your kitchen drains and the sewer, that slows the flow enough to let grease float and solids settle before the water discharges.

There are two device categories. A hydromechanical grease interceptor (HGI) — often called a grease trap — is a small unit (35–100 gallon capacity) installed under a sink or in a floor vault. It handles low flow rates and requires frequent cleaning, sometimes weekly. A gravity grease interceptor (GGI) is a large in-ground concrete or fiberglass tank, typically 750–2,000+ gallons, installed outside the building. It handles higher flow rates and gets pumped on a monthly or quarterly schedule depending on loading. For most full-service South Bay restaurants, a gravity interceptor is what the city requires.

The distinction matters because operators who inherit an undersized HGI from a previous tenant and assume it's sufficient for a full commercial kitchen are usually wrong — and the FOG inspector will tell them so, in writing, with a correction notice attached.

LA County Sanitation and most South Bay municipal FOG programs size interceptors using the Uniform Plumbing Code (UPC) method or their own published worksheets — but the underlying calculation is the same. You add up the drain flow rates (in gallons per minute) for every fixture discharging into the interceptor: pre-rinse spray valves, pot sinks, floor sinks, hood wash systems, and commercial dishwashers. Each fixture has a rated flow rate in the UPC tables. That total GPM figure, multiplied by a retention time factor (typically 2 minutes for interceptors serving commercial dishwashers, 2.5 for standard), gives you the required interceptor capacity in gallons.

Commercial dishwashers get special treatment in the calculation. A high-temperature conveyor machine can discharge 2–4 GPM continuously during a wash cycle. That single piece of equipment often drives the interceptor size more than everything else in the kitchen combined. If you upgrade your dishwasher after installation — say, swapping a stationary rack unit for a conveyor — you may have just pushed yourself out of compliance without changing anything else.

In practice, the city's FOG department reviews your plumbing plans during permit and signs off on the proposed interceptor size. But plan review and field reality often diverge. We regularly see [commercial plumbing](/commercial-plumbing) inspections where the installed unit is the size specified on a 15-year-old plan set that predates a kitchen equipment upgrade by the previous tenant. That's a compliance problem the current operator inherits — and owns.

The minimum size most South Bay jurisdictions will approve for a full-service restaurant is 1,000 gallons. High-volume kitchens with conveyor dishwashers and multiple prep sinks routinely need 1,500–2,000 gallons. If you're in a multi-tenant food hall — like several newer developments in Culver City's Fox Hills or along Hawthorne Boulevard in Lawndale — shared interceptors are sometimes permitted, but each tenant's discharge load must be documented separately.

The 25% rule is the most common pumping trigger in South Bay FOG ordinances: when the combined depth of the floating grease cap and settled solids reaches 25% of the interceptor's liquid capacity, it must be pumped. In practical terms, that means grease plus solids totaling more than 6 inches in a standard 1,000-gallon tank requires immediate service. Inspectors measure this with a grease stick on every inspection visit.

Most ordinances also impose a maximum interval regardless of accumulation. LA County Sanitation typically requires pumping at least every 90 days for a full-service restaurant, with some high-volume or problem facilities placed on 30-day schedules by enforcement order. Cities with their own sewer systems — El Segundo runs its own municipal sewer separate from the county system — may have different intervals, so verify with the authority having jurisdiction before you set a service calendar.

The practical answer for a new restaurant is to pump every 30–45 days for the first three months and measure accumulation rates. Once you have three or four data points showing your actual loading, you can establish a defensible schedule and adjust from there. A [hydro-jetting service](/services/hydro-jetting) on the interceptor outlet line at the same interval keeps downstream buildup from becoming its own compliance problem.

Don't let a pumping contractor tell you 90 days is fine without measuring. That's their convenience schedule, not yours. If an inspector finds your interceptor above 25% capacity between service visits, the violation is yours — not the pumping company's.

A FOG inspection isn't an audit of your equipment — it's an audit of your records. The inspector wants a logbook, on-site, showing: every pump-out date, the pumping contractor's name and license number, the volume removed, the manifest number from the waste hauler, and a notation of the measured grease and solids depth before and after service. That last item is important. Many operators get the pump-out but never record the pre-pump measurement, which means they can't demonstrate they were pumping before hitting the 25% threshold.

You also need the original installation permit and inspection record for the interceptor, a current-version plumbing plan showing the interceptor location and connections, and a signed Best Management Practices (BMP) agreement on file with the city. The BMP agreement is a one-time form, but inspectors ask for it constantly. If you took over an existing space and the previous operator's paperwork didn't transfer, get a copy from the city's FOG program before your first inspection.

Some cities also require a Grease Interceptor Monitoring Report submitted quarterly by a licensed plumber — not just a pumping contractor. Gardena's Western Avenue corridor has seen enforcement push on this point specifically, where multi-unit restaurant strips had pump-out records but no licensed-contractor certification attached. If your city requires it, that certification needs to come from a C-36 licensed plumber.

First-time administrative citations for FOG violations across LA County jurisdictions typically run $100–$250 per violation per day. That sounds manageable until you realize a single inspection can generate three or four separate violation line items — overloaded interceptor, incomplete logbook, missing BMP agreement, and unpermitted equipment modification — each accruing daily until corrected and re-inspected. A two-week correction window at four violations adds up to roughly $1,400–$2,800 minimum.

Repeat violations escalate to formal enforcement. That can mean mandatory sewer surveillance cameras on your lateral at your expense, compliance schedules with quarterly city inspections for 12–24 months, and fines that step up to $1,000–$2,500 per day under the Clean Water Act's administrative penalty structure when a discharge affects the regional sewer system. New restaurant owners in Inglewood's Morningside Park and Downtown Culver City have both seen enforcement escalate to this level in recent years, typically because the original grease interceptor was undersized for the new tenant's equipment load and nobody caught it before opening.

The city can also revoke your sewer use permit, which effectively closes the kitchen. That's rare, but it's not theoretical — it's the end-stage of an enforcement escalation that started with a missed pump-out log entry.

Before you take over any South Bay restaurant space, get the interceptor inspection record from the current or previous tenant. If they can't produce it, assume the worst: the unit is undersized, overdue for pumping, or both. A [commercial plumbing inspection in Torrance](/service-areas/torrance/commercial-plumbing) — or whichever city the space is in — takes roughly two hours and tells you the interceptor size, condition, last service date, and whether the existing plumbing configuration matches the permitted plans.

Also verify whether the space has ever been cited by the local FOG program. That's public record in most jurisdictions; the city's stormwater or sanitation department can tell you whether the address has open or past violations. Inheriting a problem-address history doesn't automatically mean you inherit the violations, but it does mean the city inspector knows the address and will visit early.

If the interceptor is undersized for your planned equipment list, budget for replacement before you open. A new 1,500-gallon fiberglass gravity interceptor, installed with permits, runs roughly $8,000–$15,000 depending on access, depth, and whether the parking lot or kitchen floor needs to be cut. That's a known number you can negotiate into the lease. A FOG enforcement action after you're open, with a full kitchen crew and lease obligations, is not a negotiable number.

If you're opening a new restaurant, taking over an existing space, or operating a kitchen that hasn't had a grease interceptor assessment in the past 18 months, the first step is a licensed inspection. Our crew operates as a Licensed C-36 #901735 commercial plumbing contractor across 16 South Bay cities, and we've sized, permitted, installed, and inspected interceptors from Long Beach's Belmont Shore to Lomita to El Segundo's Smoky Hollow. We know what each local FOG program actually wants to see — not just what the UPC says.

Call (310) 808-7343 to schedule a commercial site assessment. We can pull the city's FOG requirements for your address, measure your existing interceptor, review your logbook against what an inspector will check, and give you a written scope if anything needs correction. No overtime fees, 24/7 dispatch for emergencies — and if your kitchen goes down because of a blocked lateral, our 60-minute target response applies to commercial calls too.