Grease Interceptors and Traps for Fullerton Restaurants

What the interceptor does all day

Kitchen wastewater carries fats, oils and grease, often shortened to FOG, along with food solids. Grease is lighter than water, so if the flow slows down long enough it floats to the top and solids sink to the bottom. A grease interceptor is a tank built to slow the water down and hold it, with baffles that keep the floating grease and the settled solids in place while cleaner water leaves through the outlet.

When it works, the interceptor protects the city sewer and your own building lateral. When it is overfull, undersized or damaged, grease passes straight through and coats the pipe downstream, or the tank backs water up into the kitchen. Most repeat grease problems in restaurants trace back to an interceptor that is not being emptied often enough for the kitchen's volume.

Terms you will hear

Grease trap: Usually a small unit under or next to a sink or fixture. Often cleaned by staff or a service on a short schedule.
Grease interceptor: Usually a larger tank, often buried outside or under the floor, that serves several fixtures or the whole kitchen and is emptied by a pumping truck.
FOG: Fats, oils and grease. The material the interceptor is meant to capture.
Baffle: An internal wall that slows the flow and stops grease from leaving with the water. A broken baffle lets grease pass.
Sample box or sample port: An access point downstream where an inspector or plumber can see what is leaving the interceptor.
Pumping log: The record of each cleaning: date, who did it and how full the unit was. Keep it where inspectors and managers can find it.

Signs the interceptor is the problem

Several kitchen drains slow down at the same time.
Odor around the interceptor lid or manhole cover.
Grease visible in the downstream clean-out or sample port.
Backups that clear right after pumping and return before the next one.
A lid that is cracked, rocking or hard to seal.
No one can say when it was last pumped.

Which fix fits the problem?

IfThe unit is full and the log shows a long gap since pumpingHave it pumped, record the fill level, and shorten the interval.
IfIt fills too fast even with frequent pumpingAsk a plumber whether the unit is undersized for your current volume and check with the city about sizing rules.
IfGrease is passing through a unit that is not fullHave the baffles, inlet and outlet inspected for damage or missing parts.
IfLines between the kitchen and the interceptor keep cloggingThe problem may be in the pipes, not the tank. Consider jetting and a camera inspection.
IfYou are adding fixtures or changing the menuTalk to the city and a plumber before the change, because the existing unit may not be enough.

Sizing, location and the city

How large an interceptor must be, where it can sit, which fixtures must drain through it and how often it must be serviced are set by local rules and the plumbing code, not by the plumber's preference. Those rules can change and can depend on the kind of food business. Check with the City of Fullerton before installing, replacing or relocating an interceptor, and before a change of use that adds cooking.

Location matters for maintenance as much as for code. An interceptor under the kitchen floor means a pumping hose running through your space; one outside in the parking lot needs clear truck access. Ask how the unit will be reached, how often, and whether service can happen outside business hours.

Questions for your plumber or pumper

What size is our interceptor, and is that enough for the fixtures we have now?
Are the baffles, inlet and outlet in good condition?
How full was it at this pumping, and what interval do you suggest?
Which of our fixtures drain through it, and which should?
Will you give us a written service record for our log?

Common questions

Do dishwashers drain to the grease interceptor?

It depends on the installation and local rules. Some jurisdictions want certain fixtures routed through the interceptor and others kept out. Ask a plumber what yours does, and check with the city for current requirements.

Can staff clean the grease interceptor themselves?

Small under-sink traps are sometimes cleaned in-house. Large in-ground interceptors should be pumped by a service with the right equipment, and staff should never enter a vault.

Why does the interceptor smell even after pumping?

A poor lid seal, a damaged vent, grease left on the walls or a problem downstream can all cause odor. Ask the service to check the lid gasket and whether the tank was fully cleaned.

General information for Fullerton, not a quote or professional advice. In an emergency, call 911.