Operational Support

Why Restaurant Kitchen Drains Keep Backing Up in Los Angeles

The connection between grease traps, drain lines, and operational downtime — and when cleaning or hydro jetting may help.

LA Restaurant Services · Field Technician Notes

The direct answer

Restaurant kitchen drains back up because grease and food debris accumulate faster than they drain. This happens in three main places: inside your grease trap (when it fills past 25% capacity), inside drain lines (when FOG hardens and narrows the pipe), and at floor drains (when the main trap is over-capacity and grease bypasses the baffle).

One backup is a symptom. Recurring backups signal that your grease trap service is not keeping up with your actual kitchen discharge — or your drain lines need hydro jetting to clear hardened FOG buildup.

The main causes

Grease and FOG (fats, oils, grease) buildup

Every dish pan, prep sink, and floor drain in a commercial kitchen discharges grease. Over weeks and months, this FOG accumulates inside drain lines, traps, and interceptors. It hardens, traps food particles, and narrows the pipe diameter until flow slows to a crawl.

Undersized grease trap or interceptor

If your trap is too small for your actual kitchen volume, it reaches 25% capacity before scheduled service. Grease bypasses the baffle and clogs downstream lines, causing floor drain backups and slow prep sinks.

Food particles and debris accumulation

Solid food waste — vegetable scraps, meat bits, rice, pasta — combines with grease inside drain lines and traps. This sludge builds up faster than grease alone and is harder to clear with a simple drain snake.

Old or corroded pipes

Older commercial kitchens may have galvanized or cast iron drain lines that have corroded internally, creating rough surfaces where FOG and food particle sticks. New drains are smoother and drain faster, but even new lines clog if grease traps are not serviced regularly.

Where backups happen and what they tell you

Floor drains

Water pools or drains slowly after dishwashing

Prep sinks

Water backs up when multiple sinks drain at once

Dish room

Dishwasher outlet backs up into prep area or floors

Multiple locations

Several areas back up at the same time during rush periods

Multiple areas backing up at once? This usually means your main grease trap is at or past capacity. A grease trap service is the first step. If backups persist after service, your drain lines may have hardened FOG deposits that need commercial hydro jetting to clear. Check signs your restaurant needs hydro jetting and grease interceptor pumping to assess your situation.

Why quick fixes don't solve recurring backups

A plumber with a drain snake can clear a temporary clog, but if the underlying problem is an over-capacity grease trap or hardened FOG deposits in the lines, the backup will return in days or weeks. You end up paying for repeated service calls instead of fixing the root cause.

The solution is two-part: First, ensure your grease trap is serviced on schedule and never exceeds 25% capacity. See how often Los Angeles restaurants need grease trap service for intervals by kitchen type. Second, if backups persist, use hydro jetting to blast out hardened FOG inside the drain lines, then maintain a regular service schedule to prevent recurrence.

Experiencing recurring backups?

We offer grease trap cleaning and hydro jetting to diagnose and fix the problem.

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